Updated on 2024/07/22

写真a

 
ISHIYAMA, Atsushi
 
Affiliation
Faculty of Science and Engineering, School of Advanced Science and Engineering
Job title
Professor
Degree
Dr. of Engineering ( Waseda University )

Research Experience

  • 1991.04
    -
    Now

    Waseda University, Professor

  • 2014.11
    -
    2018.11

    Waseda University

  • 2007.04
    -
    2010.09

    Waseda University

  • 1985.04
    -
    1991.03

    Waseda University, Assistant Professor

  • 1983.04
    -
    1985.03

    Waseda University, Lectu

  • 1979.04
    -
    1983.03

    Waseda University, Research Assistant

▼display all

Education Background

  •  
    -
    1983

    Waseda University   Graduate School, Division of Science and Engineering   Electrical Engineering  

  •  
    -
    1977

    Waseda University   Faculty of Science and Engineering   Electrical Engineering  

Committee Memberships

  • 2021.06
    -
    Now

    (公益)東電記念財団  理事

  • 2015.06
    -
    2018.05

    日本生体磁気学会  副会長

  • 2010.06
    -
    2018.05

    (公益)低温工学・超電導学会  理事(学会誌出版委員長)

Professional Memberships

  •  
     
     

    電気学会

  •  
     
     

    日本生体磁気学会

  •  
     
     

    低温工学・超電導学会

Research Areas

  • Power engineering

Research Interests

  • Electric Machine, Application of Supercunductivity, Electromagnetic Computation, Biomagnetcs

Awards

  • 業績賞・学術業績

    2020   (公益財団法人)低温工学・超電導学会  

    Winner: 石山敦士

  • 優秀技術活動賞・技術報告賞

    2017.06   電気学会   「イットリウム系高温超電導コイル化技術調査専門委員会」

  • 電気科学技術奨励賞

    2012   ( 公益財団法人)電気科学技術奨励会   「高強度超電導コイルの開発」

    Winner: 石山敦士, 渡部智則, 淡路智

 

Papers

  • Test of High Temperature Superconducting REBCO Coil Assembly for a Multi-Frequency ECR Ion Source

    Tsun Him Chong, Mitsuhiro Fukuda, Tetsuhiko Yorita, Hiroki Kanda, Shigeo Nagaya, Atsushi Ishiyama, So Noguchi, Hiroshi Ueda, Satoshi Fukui, Tomonori Watanabe, Jun Yoshida, Takashi Hirayama, Yukio Mikami, Yuji Matsubara, Takashi Kitamura

    IEEE Transactions on Applied Superconductivity    2024.08  [Refereed]  [International journal]

    DOI

    Scopus

  • Fabrication and Experiments on a 1/2-Scale Demonstration NI-REBCO Coil System of a Skeleton Cyclotron for Cancer Therapy

    Rui Kumagai, Atsushi Ishiyama, Hiroshi Ueda, So Noguchi, Tomonori Watanabe, Mitsuhiro Fukuda, Gen Nishijima, Jun Yoshida

    IEEE Transactions on Applied Superconductivity   34 ( 5 ) 1 - 5  2024.08

    DOI

  • Experiment and Simulation on Mechanical Behavior in 1/2-Scale Demonstration REBCO Coil System of Skeleton Cyclotron for Cancer Therapy

    Hiroshi Ueda, Ryota Komae, Aoi Yamashita, Ryota Inoue, SeokBeom Kim, So Noguchi, Tomonori Watanabe, Mitsuhiro Fukuda, Gen Nishijima, Rui Kumagai, Atsushi Ishiyama

    IEEE Transactions on Applied Superconductivity   34 ( 5 ) 1 - 5  2024.08

    DOI

  • Numerical Evaluation of Screening Current-Induced Magnetic Field in 1/2-scale No-Insulation REBCO Coil System of Skeleton Cyclotron for Cancer Therapy

    Kaito Ota, Atsushi Ishiyama, Hiroshi Ueda, So Noguchi

    IEEE Transactions on Applied Superconductivity    2023

     View Summary

    A new-generation accelerator named “skeleton cyclotron” is being developed for the stable production of 211At used for targeted alpha-particle therapy, which is expected to be effective in treating advanced cancer. The coil system for skeleton cyclotron consists of two types of air-core no-insulation (NI) REBCO coils: a circular main coil and a noncircular sector coil. To investigate the electromagnetic, thermal, and mechanical characteristics, we fabricated the ultra-baby skeleton cyclotron (UBSC) coil system, which is a 1/2-scale demonstration model of the NI-REBCO coil system. In NI-REBCO coils, the current flows in the radial direction, causing an excitation delay. Because this affects the magnetic field, it is necessary to perform screening current-induced magnetic Field (SCIF) analysis that considers the current flowing in the radial direction in NI coil winding. Therefore, we developed a new simple calculation method for the SCIF using only electric circuits. In this study, we evaluated the electromagnetic behavior of 1/2-scale NI-REBCO coil system for UBSC by using the newly developed calculation method based on electrical circuit and confirmed its validity through comparison with experimental results.

    DOI

    Scopus

  • AC Loss Evaluation of NI REBCO Pancake Coils in External Low-Frequency Magnetic Field

    Kazuhiro Daiho, Atsushi Ishiyama, So Noguchi

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   32 ( 6 )  2022.09

     View Summary

    No-insulation (NI) rare-earth barium copper oxide (REBCO) pancake coils have attracted much attention because of their high thermal stability. It is, therefore, expected to apply NI REBCO pancake coils to various applications. In recent years, there have been discussions on the possibility of applying NI REBCO pancake coils to field coils of synchronous motors for ship and aircraft propulsion. NI REBCO field coils would be exposed to an AC magnetic field of similar to 1 Hz. The AC losses must be discussed because a current is induced in an NI REBCO coil under externa AC field. AC losses in NI REBCO pancake coils exposed to changing magnetic fields should be investigated in detail. In this paper, the AC Joule loss of the NI-REBCO pancake coils is investigated by simulation using a partial element equivalent circuit (PEEC) model. The magnetization loss is also investigated based on the Bean model when a low-frequency AC magnetic field is applied to the NI REBCO pancake coil. From the simulation results, we concluded a high contact resistivity can sufficiently reduce the Joule loss.

    DOI

    Scopus

    4
    Citation
    (Scopus)
  • Numerical Evaluation of Transient Thermal Stability of No-Insulation REBCO Pancake Coils With a Noncontact Area Between Turns

    Mayu Kitamura, Kyoka Tsuyoshi, Ui Nemoto, Atsushi Ishiyama, So Noguchi

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   32 ( 6 )  2022.09

     View Summary

    We have been developing a no-insulation (NI) REBCO coil for applications in medical cyclotrons for cancer therapy and high-magnetic-field whole-body MRIs. NI-REBCO pancake coil is expected to realize both high current density and thermal stability, which are essentially trade-off relationships. Because electrical insulation is absent in an NI coil, the operating current can bypass toward adjacent turns to avoid the defect area when a local defect occurs. Using this feature, we investigated the possibility of continuous operation even if there is a local defect in a part of the coil windings. However, the contact condition between turns in actual coil windings is not uniform, and there is a possibility of an area that is not completely in contact. Moreover, when winding noncircular coils, e.g., coils for an accelerator, the noncontact area between turns can be large since the straight area is not tensioned. In such a case, even if a local defect occurs, it cannot bypass toward adjacent turns, compromising thermal stability. In this study, we examined the thermal stability of NI-REBCO pancake coils when a local defect occurred using the length, number, and location of noncontact areas between turns as parameters. We also examined the possibility of continuous operation and explored conditions that allow for continuous operation.

    DOI

    Scopus

  • Numerical Evaluation of Electromagnetic Behavior of Multi-Stacked No-Insulation REBCO Coil System for Whole-Body MRIs and Medical Cyclotrons

    Ui Nemoto, Kyoka Tsuyoshi, Mayu Kitamura, Atsushi Ishiyama, So Noguchi

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   32 ( 6 )  2022.09

     View Summary

    We have been developing a no-insulation (NI) REBCO pancake coil technology for applications in medical cyclotrons and high-field whole-body MRI. The thermal and electromagnetic behaviors of multi-stacked NI-REBCO double pancake coils are numerically analyzed in this study when a local defect occurs in one coil using coil diameter and operating temperature parameters. Based on changes in voltage at both ends of the coil and the magnetic field at the center, we present a numerical study of the possibility of continuous operation after the occurrence of a local defect. In the numerical analysis, a new simplified model based on the PEEC model (Partial Element Equivalent Circuit model) is suggested and used for current distribution analysis, and the results are compared.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • An Optimal Configuration Method of Superconducting Magnet With Iron Shield Using Model Order Reduction

    So Noguchi, Hiroshi Ueda, Tomonori Watanabe, Shigeo Nagaya, Atsushi Ishiyama, Mitsuhiro Fukuda

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   32 ( 6 )  2022.09

     View Summary

    We have been developing a cyclotron accelerator for radioisotope production of medical use. The features of developed cyclotron system are compactness, light weight, and multi energy outputs. To achieve such features, coils are wound with rare-earth barium copper oxide (REBCO) tapes and the magnet has no iron core to generate an azimuthal varying field (AVF). To install the developed cyclotron accelerator into hospitals, an iron shield is needed for protection of leakage radiation and magnetic field. In this paper, to optimally design main coils with iron shield, a fast field computation method called "Model Order Reduction (MOR)" is adopted. Using MOR technique, the field computation is accelerated similar to 50 times. The error of MOR field computation is sufficiently small. Hence, the MOR is effective in the optimal configuration design of coils with iron shield. The optimized configuration of a miniaturized cyclotron accelerator magnet is also shown.

    DOI

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  • Numerical Evaluation of Screening Current-Induced Magnetic Field in REBCO Coil System for Skeleton Cyclotron Using a Full-Scale Model

    Kodai Shirai, Atsushi Ishiyama, Hiroshi Ueda, So Noguchi, Tomonori Watanabe, Shigeo Nagaya, Mitsuhiro Fukuda

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   32 ( 6 )  2022.09

     View Summary

    We have been developing a new-generation accelerator named high-temperature superconducting skeleton cyclotron (HTS-SC), an extremely compact and high-intensity accelerator capable of producing At-211 for targeted alpha-particle therapy, which is expected to be effective in treating advanced cancer. The coil system for HTS-SC consists of multiple air-core REBCO coils that create a magnetic field of high intensity and precision required for particle acceleration. The HTS-SC needs high-precision magnetic field distribution and temporal stability in the particle acceleration plane. However, the magnetic field induced by the screening current in the REBCO tape (SCIF: Screening Current-Induced magnetic Field) deteriorates the quality of the generated magnetic field spatially and changes it temporally. Therefore, in this paper, the SCIF is evaluated based on numerical analysis for a full-scale REBCO coil system designed for targeted alpha-particle therapy. In addition, the effect of the overshoot method, which is one of the current waveform control methods used to reduce the effect of SCIF on temporal stability, is investigated.

    DOI

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    2
    Citation
    (Scopus)
  • Numerical Evaluation of the Transient Thermal Stability of No-Insulation Pancake Coils Wound With a REBCO-Coated Conductor With Some Defects

    Kyoka Tsuyoshi, Mayu Kitamura, Ui Nemoto, So Noguchi, Atsushi Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   32 ( 6 )  2022.09

     View Summary

    We have been developing large-diameter (m-class) no-insulation (NI) REBCO coil systems for applications in areas, such as medical cyclotrons and high-magnetic-field whole-body magnetic resonance imaging (MRI). NI coil technology can achieve both high thermal stability and current density, which have an in-verse relationship. Our previous studies revealed that the application of NI winding technology can allow a coil to continuously operate even when some parts of the coil windings are degraded. Accordingly, by applying the NI winding technology, the use of REBCO-coated conductors with defects or degradation, that is, coil production that allows for variations in conductor characteristics, can result in reduced costs. In this study, the transient thermal stability of NI pancake coils wound with a REBCO-coated conductor with one or more defects was analyzed and evaluated numerically. The conditions for stable operations in a coil with defects were clarified using turn-to-turn contact electrical resistance and I-OP/I-C ratios as parameters. In addition, we evaluated the possibility of establishing a monitoring technology to detect the state of health of the coil by observing changes in the voltage at both ends of the coil to see if any new deterioration has occurred.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Numerical Evaluation on Mechanical Behavior of No-Insulation REBCO Pancake Coils in Small-Scale Model of Skeleton Cyclotron

    Yuta Miyake, Yuki Nakai, Ryota Inoue, SeokBeom Kim, Hiroshi Ueda, So Noguchi, Tomonori Watanabe, Shigeo Nagaya, Mitsuhiro Fukuda, Atsushi Ishiyama

    IEEE Transactions on Applied Superconductivity   32 ( 6 ) 1 - 5  2022.09

    DOI

  • Numerical Evaluation on Quench Behavior of No-Insulation REBCO Coil System in Small-Scale Model of Skeleton Cyclotron

    Yuki Nakai, Yuta Miyake, Ryota Inoue, SeokBeom Kim, Hiroshi Ueda, So Noguchi, Tomonori Watanabe, Shigeo Nagaya, Mitsuhiro Fukuda, Atsushi Ishiyama

    IEEE Transactions on Applied Superconductivity   32 ( 6 ) 1 - 5  2022.09

    DOI

  • Mechanical Strength Evaluation of a Yoroi-Coil Structured Non-Circular REBCO Pancake Coil in High Magnetic Field

    Tomonori Watanabe, Shigeo Nagaya, Atsushi Ishiyama, So Noguchi, Hiroshi Ueda, Gen Nishijima

    IEEE Transactions on Applied Superconductivity   32 ( 6 )  2022.09

     View Summary

    In order to achieve a high intensity and compact multifunctional air-core cyclotron, the behavior of non-circular coils in a high magnetic field at 4.2 K were investigated. Two types of isosceles triangle shaped double-pancake coils: a coil with reinforcement by Yoroi-coil (Y-based oxide superconductor and reinforcing outer integrated coil) structuring and a coil without reinforcement, were manufactured and their behaviors were observed when current was applied to each coil in a high magnetic field. The non-reinforcement coil showed in 10 T external magnetic field that the superconducting properties of the coil were partially lost and a voltage generated in the coil winding was observed when the applied current exceeded 160 A. After disassembling this coil, it was found that the superconducting tape in the coil winding was plastically deformed and permanently bent at the corners. The reinforced coil due to Yoroi-coil structuring was powered up to the coil current of 300 A in a magnetic field of 14 T. A voltage of 0.3 mV was observed when the coil current was 277 A, and the excitation was terminated when the voltage reached 0.6 mV at 300 A. The coil winding, after the current flowing up to 300 A in 14 T field, indicated that the deformation of it was significantly limited. It was confirmed that the Yoroi-coil type structural reinforcement, even for triangular coils, has sufficient mechanical strength under the conditions of our air-core cyclotron.

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • Evaluation Criterion for Determining Turn-to-Turn Contact Electrical Resistance Satisfying High Thermal Stability and Shortening Charging Delay in NI-REBCO Coils for MRIs

    Yuka Yoshihara, Mai Hamanaka, Kyoka Tsuyoshi, Mayu Kitamura, Ui Nemoto, So Noguchi, Atsushi Ishiyama

    IEEE Transactions on Applied Superconductivity   31 ( 5 )  2021.08

     View Summary

    We have been developing a no-insulation (NI) coil technology to achieve high thermal stability and high current density. NI coils can continue to operate even if a part of the coils degrades; however, a charging delay occurs in the coils. Moreover, the turn-to-turn contact electrical resistance of the NI coils must be increased to shorten the charging delay; however, a large turn-to-turn contact electrical resistance reduces thermal stability. In this study, using turn-to-turn contact electrical resistance and IOP/IC ratios as parameters, we analyze thermal stability and consider the possibility that NI coils can continue to operate even if they have local defects. Furthermore, to establish an evaluation criterion for determining turn-to-turn contact electrical resistance that can shorten charging delay and ensure high thermal stability, we analyze and evaluate the relationship between turn-to-turn contact electrical resistance and thermal stability, focusing on three types of heat generation.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Numerical Analysis of the Reduction of Screening-Current-Induced Magnetic Field in Copper-Plated and Striated REBCO-Coated Conductor Wound into Pancake Coils

    Hinako Ishizaki, Satomi Ueda, Takamitsu Ogata, Atsushi Ishiyama, Hiroshi Ueda, So Noguchi

    IEEE Transactions on Applied Superconductivity   31 ( 5 )  2021.08  [Refereed]

     View Summary

    We aim to develop REBCO coil systems for high-magnetic-field whole-body magnetic resonance imaging and medical cyclotron for cancer therapy. These applications require high temporal stability and spatial uniformity of the generated magnetic field. Although the magnetic field generated during excitation changes very slowly, a screening-current-induced magnetic field (SCIF) is generated, which affects the required accuracy of the magnetic field. To reduce the SCIF, we focus on two methods: 1) a current control method, and 2) the use of striated coated conductors. When adopting a striated coated conductor, it is necessary to plate copper onto it in order to maintain its thermal stability and mechanical strength. However, in the copper-plated layer, changes in the magnetic field induce a coupling current, which flows between the filaments of the REBCO coated conductor. In this study, we apply the overshoot method with a plateau as a current control to eliminate the effect of coupling currents in the copper plating layer. We numerically analyzed the effectiveness of this overshoot method by visualizing the changes in the current distributions in a model pancake coil wound with a REBCO-coated conductor separated into two filaments. For that purpose, we used a three-dimensional nonlinear transient electromagnetic field computation in which the spiral arrangement of the pancake coil windings is appropriately considered.

    DOI

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    3
    Citation
    (Scopus)
  • Numerical Evaluation of Screening Current-Induced Magnetic Field Considering Variable Output Energy in REBCO Coil System of Skeleton Cyclotron for Cancer Therapy

    Takamitsu Ogata, Kodai Shirai, Atsushi Ishiyama, Hiroshi Ueda, So Noguchi, Tomonori Watanabe, Shigeo Nagaya, Mitsuhiro Fukuda

    IEEE Transactions on Applied Superconductivity   31 ( 5 ) 1 - 5  2021.08  [Refereed]

    DOI

  • Numerical Evaluation of Screening Current-Induced Magnetic Field in No-Insulation REBCO Coil Systems

    Satomi Ueda, Atsushi Ishiyama, Hiroshi Ueda, So Noguchi

    IEEE Transactions on Applied Superconductivity   31 ( 5 ) 1 - 5  2021.08  [Refereed]

    DOI

  • Numerical Evaluation on Electromagnetic and Thermal Stresses in Non-Circular REBCO Pancake Coils of Multi-Coil System For Skeleton Cyclotron

    Hiroshi Ueda, Yuta Miyake, Yuta Awazu, Ryota Inoue, SeokBeom Kim, So Noguchi, Tomonori Watanabe, Shigeo Nagaya, Mitsuhiro Fukuda, Atsushi Ishiyama

    IEEE Transactions on Applied Superconductivity   31 ( 5 ) 1 - 5  2021.08  [Refereed]

    DOI

  • OPTIMAL DESIGN OF SUPERCONDUCTING MAGNETS FOR WHOLE-BODY NMR IMAGING.

    A. Ishiyama, T. Yokoi, S. Takamori, T. Onuki

    IEEE Transactions on Magnetics   MAG-23 ( 2 )  2021.03

     View Summary

    An technique for optimal design of magnetic field systems that utilizes a hybrid finite-element-boundary-element HFB method and mathematical programming is proposed. This technique is applied to the design of a high-homogeneous-field superconducting magnet system with an environmental shield for whole-body NMR imaging. Design results for three 1. 0-Tesla magnet systems with different types of shields (an iron shield, a shield magnet, and a combination of the iron shield and the shield magnet) are shown.

  • Influence of Coil Size and Operating Temperature on the Transient Stability of a Multi-Stacked No-Insulation REBCO Pancake Coil System

    Haruka Onoshita, Yuka Yoshihara, Hiroshi Ueda, So Noguchi, Atsushi Ishiyama

    IEEE Transactions on Applied Superconductivity   30 ( 4 ) 4702605  2020.06  [Refereed]

     View Summary

    The no-insulation (NI) coil is a technology expected to realize both high current density and high thermal stability which are essentially trade-off relationship in REBCO coil application. This technique has been studied mainly for application to small-diameter inner coils of NMR magnets exceeding 30 T. In this case, the coil is cooled using 4.2-K liquid He. We are developing an NI-REBCO coil system for high-magnetic-field whole-body MRI, and for a medical cyclotron to be used for cancer therapy. The NI-REBCO coil which we aim for development has a diameter of similar to 1 m, a generated magnetic field is similar to 10 T, and a conduction cooling around 30 K is assumed. Because the size, operating temperature, and magnetic field differ from those of NMR coil, it is possible that the electromagnetic, thermal, and mechanical behaviors will be quite different. In this paper, we report on these behaviors when a local deterioration occurs in NI-REBCO double-pancake coils using numerical analysis considering coil size, operating temperature, and magnetic field as parameters. For the numerical simulation, we conducted a coupled analysis of current distribution analysis based on PEEC (Partial Element Equivalent Circuit) model and thermal analysis by the 2-dimensional finite element method.

    DOI

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    7
    Citation
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  • Optimum design of cryogenic pump for circulation cooling of high temperature superconducting cables

    Kenta Tadakuma, Kazuhiro Kajikawa, Yasuharu Kamioka, Atsushi Ishiyama, Shinsaku Imagawa, Taketsune Nakamura, Hirokazu Hirai, Shinsuke Ozaki

    Journal of Physics: Conference Series   1293   012070 - 012070  2019.09  [Refereed]

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  • Experiments on the Effects of Local Normal Transitions in Multi-Stacked No-Insulation REBCO Pancake Coils

    Tetsuri Ichikawa, Yuta Kakimoto, Haruka Onoshita, Tetsuro Kinpara, So Noguchi, Shigeo Nagaya, Tomonori Watanabe, Atsushi Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   29 ( 5 )  2019.08  [Refereed]

     View Summary

    No-insulation (NI) coils are an important technique for high-field magnetic resonance imaging (MRI). One of the tech-nical issues with NI coils is their thermal and electromagnetic be-havior when a local normal transition occurs. Given that multiple stacked coils are used in MRI, the interaction between coils must also be investigated, because a local normal transition may affect the other NI coils through magnetic coupling. In fact, when a local normal transition occurs, there is a possibility that large electro-magnetic forces are applied to the other coils, or quench may be induced in some of them. Even though overcurrent tests of stacked NI coils have been conducted, the results are not helpful in ac-tual MRI operation. In this study, we investigate the effects of the occurrence of a local normal transition in multi-stacked NI coil systems under conditions similar to those of actual operation, with a constant transport current below the coil’s Ic . The occurrence of a local normal transition is simulated by applying current to a heater inserted in manufactured small NI double pancake coils. To evaluate the interaction between NI coils, the voltage and changes in the generated magnetic field are measured at each coil. We also show the current distribution in the coils, as obtained by the partial element equivalent circuit method. The obtained results allow us to evaluate the interaction of the NI coils and evaluate coil protection methods.

    DOI

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    3
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  • Comparison Between Simulation and Experimental Results of Liquid Nitrogen Coolant Distribution in a 66-kV 40-m Model HTS Power Cable System Experiencing Short-Circuit Accidents

    Daichi Horita, Koh Agatsuma, Atsushi Ishiyama, Takato Masuda, Toshiya Morimura, Tomoo Mimura

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   29 ( 5 )  2019.08  [Refereed]

     View Summary

    In this study, a computer program was developed to simulate the temperature and pressure distributions of a liquid ni-trogen (LN) coolant in a high-temperature superconducting (HTS) power cable. This program is important for realizing a practical HTS power cable. According to the Japanese criterion for a 66-kV power-transmission system, in a worst case short-circuit accident, a fault current of 31.5 kA may flow in a 66-kV cable system for 2 s. In addition, when a short-circuit accident occurs, the temperature and pressure of an LN coolant increase rapidly The temperature behaviors of the cable cores and coolant were analyzed by solving the nonlinear partial differential heat-conduction equations in the cable cores by considering the energy balance of the heat flow by using the finite-difference method. Moreover, the pressure behav-iors of the coolant in a cooling system were analyzed, considering the density and volume behaviors of the coolant. The simulation results for the 66-kV 40-m model cable qualitatively reproduced the experimental results satisfactorily.

    DOI

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    4
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  • Evaluation of Electromagnetic Behavior of No-Insulation REBCO Pancake Coil With Multiple Defects

    Yuta Kakimoto, Tetsuri Ichikawa, Haruka Onoshita, Tetsuro Kinpara, Atsushi Ishiyama, So Noguchi

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   29 ( 5 )  2019.08  [Refereed]

     View Summary

    We previously developed a high-magnetic-field RE-BCO coil for use in medical devices such as medical accelerators and high-magnetic-field MRI. The use of high-temperature supercon-ducting (HTS) coils in such applications necessitates their minia-turization while providing high magnetic fields. However, when the current density is improved by reducing the copper-stabilization-layer thickness in the conventional insulated HTS coil, the thermal stability is lowered, which leads to a tradeoff between high cur-rent density and high thermal stability. Therefore, we examine no-insulation (NI) coils that allow compatibility between high current density and thermal stability. Recent research has indicated that NI coils with multiple defects can afford a stable and high critical current (Ic) and operate without serious problems, which makes it possible to produce coils wound with commercial REBCO tapes containing several defects along the tape, which in turn makes fab-rication economically viable. However, there are many unknown aspects of the current, magnetic field, and heat behaviors of NI coils with defects, particularly when large currents flow through them. Here, in order to examine the behavior of a multiple-defect NI coil subjected to a large current at the temperature of ∼30 K via application of the conduction cooling method, we use a com-bination of the partial element equivalent circuit method and the finite-element method to investigate the detailed current and ther-mal behaviors. Our results indicate that defective NI coils can af-ford a critical current Ic value of ∼80% of that of defect-free NI coils, which makes our findings valuable in terms of contributing to further developments in HTS coil applications.

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    11
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  • Conceptual Design of Compact HTS Cyclotron for RI Production

    Hiroshi Ueda, Atsushi Ishiyama, So Noguchi, Tomonori Watanabe, Shigeo Nagaya, Jun Yoshida, Mitsuhiro Fukuda

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   29 ( 5 )  2019.08  [Refereed]

     View Summary

    In autumn 2017, the project "Quantum Innovation for Safe and Smart Society (QiSS)" was started in Program on Open Innovation Platform with Enterprises, Research Institute and Academia (OPERA) by Japan Science and Technology Agency (JST). One of the key issues of this project is the advancement of compact cyclotron and beam irradiation device for stable supply of short-lived radioisotope (RI). We proposed the air-core cyclotron using high-temperature superconducting (HTS) technology, named Skeleton Cyclotron, as high intensity compact cyclotron. Currently, we are carrying out a feasibility study on a variable-energy multi-particle Skeleton Cyclotron for RI production. In this paper, key issues in HTS magnet technologies for Skeleton Cyclotron and the preliminary conceptual design of variable-energy multi-particle Skeleton Cyclotron are reported.

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    23
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  • Active magnetic bearing for a liquid nitrogen pump

    Yasuharu Kamioka, Kazuhiro Kajikawa, Hirokazu Hirai, Shinsuke Ozaki, Taketsune Nakamura, Shinsaku Imagawa, Atsushi Ishiyama

    IOP Conference Series: Materials Science and Engineering   502   012153 - 012153  2019.04  [Refereed]

    DOI

  • A simple screening current-induced magnetic field estimation method for REBCO pancake coils

    Noguchi So, Ueda Hiroshi, Hahn Seungyong, Ishiyama Atsushi, Iwasa Yukikazu

    SUPERCONDUCTOR SCIENCE & TECHNOLOGY   32 ( 4 )  2019.04  [Refereed]

     View Summary

    © 2019 IOP Publishing Ltd. The development of NMR/MRI REBa 2 Cu 3 O y (REBCO, RE = rare earth) magnets is happening all over the world. It has been found that screening current-induced magnetic fields (SCMFs) are a serious problem for NMR/MRI magnets wound with REBCO tapes. The reduction of SCMFs is strongly desired, and the estimation of SCMFs is also desired at the design stage of REBCO magnets. In order to evaluate a SCMF, a finite element method (FEM) or a boundary integration method is needed thus far, and a high-level simulation technique is required. In this paper, we develop an easy method to estimate a SCMF without a high-level simulation technique. In this method, the inductance of a winding turn is calculated and then a screening current is estimated according to the magnetic field penetrating into the winding turn. The SCMF is obtained from the estimated screening current. The SCMFs computed by the proposed method were compared with measurements and simulation results of the FEM. The results agreed well, but we can see a large difference. However, the SCMFs found by the proposed method are accurate enough to know they are at the design stage without the use of a high-level simulation technique.

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    23
    Citation
    (Scopus)
  • 無絶縁REBCOパンケーキ・コイルにおける数値解析技術

    野口 聡, 植田 浩史, 石山 敦士

    低温工学   54 ( 2 ) 103 - 110  2019.03  [Refereed]  [Invited]

    DOI

  • Current Status of Numerical Simulation Techniques for High-Temperature Superconducting Application Equipment

    植田浩史, 野口聡, 石山敦士

    低温工学   54 ( 2 ) 89 - 96  2019.03  [Refereed]  [Invited]

    DOI J-GLOBAL

  • A simple protection evaluation method for no-insulation REBCO pancake coils during local normal-state transition

    So Noguchi, Seungyong Hahn, Atsushi Ishiyama, Yukikazu Iwasa

    Superconductor Science and Technology   32 ( 4 )  2019.02  [Refereed]

     View Summary

    No-insulation (NI) and metal-insulation (MI) winding techniques are promising for enhancing the thermal stability of REBCO pancake coils, toward the practical use of nuclear magnetic resonance and magnetic resonance imaging systems. The NI and MI REBCO pancake coils showed high thermal stability in many over-current tests. However, a disadvantage is a charging delay due to low turn-to-turn contact resistance. Therefore, many researchers have tried to increase turn-to-turn contact resistance to overcome the charging delay problem. Meanwhile, a partial element equivalent circuit (PEEC) model can accurately simulate the over-current and charging/discharging tests of NI REBCO
    pancake coils in detail. Using the PEEC model coupling with thermal finite element analysis (FEA), the thermal stability was evaluated during a local normal-state transition. From the simulation results, it was found that a best range of turn-to-turn contact resistance existed to keep a high thermal stability
    during a local normal-state transition. However, the PEEC and thermal FEA method requires a substantial amount of time with complicated simulation approach. In this paper, we propose a simple mathematical formulation to obtain an appropriate range of turn-to-turn contact resistance during a local normal-state transition, supposing a worst cooling condition. The simple computation is easy to use and timesaving to roughly estimate the operation reliability of NI REBCO pancake coils.

    DOI

    Scopus

    18
    Citation
    (Scopus)
  • Numerical Evaluation of Reduction Methods for Screening Current-induced Magnetic Field in a REBCO Multiple Coil System for 9.4-T Whole-body MRIs

    伊東慶太, 植田浩史, 野口聡, 石山敦士

    低温工学   54 ( 2 ) 119‐126(J‐STAGE)  2019  [Refereed]

    DOI J-GLOBAL

  • Numerical Simulation Techniques for No-Insulation REBCO Pancake Coils - Comparison of Models and Simulation-

    野口聡, 植田浩史, 石山敦士

    低温工学   54 ( 2 ) 103‐110(J‐STAGE)  2019  [Refereed]  [Invited]

    DOI J-GLOBAL

  • Safety Verification of a 275-kV HTS Cable System under Short-Circuit Current Accidents

    Yusuke Yokoo, Natsuo Takeda, Daichi Horita, Koh Agatsuma, Atsushi Ishiyama, Xudong Wang, Tomohiro Takagi, Masashi Yagi

    IEEE Transactions on Applied Superconductivity   28 ( 4 )  2018.06  [Refereed]

     View Summary

    A simulation code that analyzes the temperature and pressure in a high-temperature superconducting (HTS) power cable cooled by a forced flow of subcooled liquid nitrogen (LN) has been developed. Analysis of the HTS cable is useful for comprehending the normal operating condition and the generation of heat during the transient state. In Japan, an excessive current of 63 kA may flow in an HTS cable for 0.6 s in the worst case when a short-circuit current accident occurs in a 275-kV class cable. To assess the safety under this condition, a simulation of a 275-kV class 20-m model cable was performed, and the simulation results of the temperature profiles qualitatively agreed with the experimental results. In this study, a finite-difference method was used to solve the nonlinear partial differential equations of the heat-transfer phenomenon through heat conduction. By solving these equations, the temperature profiles of the LN coolant and the cable cores were analyzed. The GASPAK software package (Cryodata) was used to evaluate the fluid properties when the LN temperature in the cable was calculated. According to this result, the simulations focused on the analysis of a real-scale HTS cable in this work.

    DOI

    Scopus

    2
    Citation
    (Scopus)
  • Thermal and Electromagnetic Simulation of Multistacked No-Insulation REBCO Pancake Coils on Normal-State Transition by PEEC Method

    Ryosuke Miyao, Hajime Igarashi, Atsushi Ishiyama, So Noguchi

    IEEE Transactions on Applied Superconductivity   28 ( 3 )  2018.04  [Refereed]

     View Summary

    This paper presents the thermal and electromagnetic behaviors of multistacked no-insulation (NI) REBa2Cu3O7- x (REBCO, RE = rare earth) pancake coils. The NI winding technique gives a high enough thermal stability not to damage REBCO coils even though a normal-state transition occurs. The high thermal stability has been verified through overcurrent tests. Moreover, the numerical simulation of multistacked NI REBCO pancake coils has been performed to investigate the electromagnetic behaviors in detail. The simulation results also confirmed the high thermal stability of NI REBCO pancake coils. However, it does not mean that an NI REBCO magnet never quenches. In experiments, it was observed that a quench in one of the pancake coils propagated to the other pancake coils sequentially. The above sequential quench from pancake to pancake has not been confirmed in the numerical simulation since the thermal behavior is not considered. For the more reliable verification, we have developed a numerical simulation to investigate the thermal and electromagnetic behaviors by the partial element equivalent circuit method and the two-dimensional thermal finite-element method. In this paper, the six-stacked NI REBCO pancake coil is simulated with several operating temperatures, and the sequential quench is reproduced. The velocity of the sequential quench is also shown.

    DOI

    Scopus

    25
    Citation
    (Scopus)
  • An Extended Thin Approximation Method to Simulate Screening Current Induced in REBCO Coils

    So Noguchi, Seungyong Hahn, Hiroshi Ueda, Seokbeom Kim, Atsushi Ishiyama

    IEEE Transactions on Magnetics   54 ( 3 )  2018.03  [Refereed]

     View Summary

    Superconducting magnets wound with second-generation high-temperature superconductors, i.e., REBa2Cu3O7-x (REBCO, RE = Rare Earth) tapes, are desired to apply high magnetic field nuclear magnetic resonance, MRI, and accelerators. However, a major problem for practical application is an undesirable irregular magnetic field caused by screening currents induced in REBCO tapes. To investigate the screening current-induced magnetic field, a few simulation methods have been proposed. One of the effective simulation methods employs a finite-element method with a thin approximation method. Although the thin approximation method was developed to simulate eddy currents in magnetic steel sheets, and it is not applicable to REBCO tapes carrying a transport current. Therefore, the thin approximation method is extended to simulate screening currents in REBCO tapes considering a carrying transport current. To show the validity of the proposed extended thin approximation method, the screening currents of an REBCO magnet are computed, and the results are compared with the measurement and simulation results of the conventional thin approximation method. The more accurate solution is available by using the proposed methods.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Magnetoencephalography Reveals Mismatch Field Enhancement from Unexpected Syntactic Category Errors in English Sentences

    Mikio Kubota, Yumie Ono, Atsushi Ishiyama, George Zouridakis, Andrew C. Papanicolaou

    Neuroscience Letters   662   195 - 204  2018.01  [Refereed]

     View Summary

    The type of syntactic operations that increase neuronal activation in humans as a result of syntactically erroneous, unexpected lexical items in hearing sentences has remained unclear. In the present study, we used recordings of magnetoencephalographic (MEG) activity to compare bare infinitive and full infinitive constructions in English. This research aims to identify the type of syntactic deviance that may trigger an early syntax-related mismatch field (MMF) component when unexpected words appear in sentences. Six speakers of English as a first language were presented with auditory stimuli of sentences or words in a passive odd-ball paradigm while watching a silent movie. The experimental protocol included four sessions, specifically investigating the sentential (structural) versions of full (with the ‘to’ infinitival particle) and bare infinitival structures (without the particle) and the lexical (non-structure) versions of the verb either with or without the particle to determine whether the structure processing of sentences was a more crucial factor in the detection of the MMF than the simple processing of lexical items in verb-only conditions. The amplitude analysis of the resulting evoked fields showed that the presence of the syntactic category error of bare infinitival structures against syntactic predictions evoked a significantly larger MMF activation with a peak latency of approximately 200 ms in the anterior superior temporal sulci in the left hemisphere, compared with the lexical items that did not have any syntactic status. These results clearly demonstrate that syntactically unexpected, illegal input in the bare infinitival structure is likely to be noticed more robustly in the brain while processing the structural information of the entire sentence than the corresponding verb-only items.

    DOI PubMed

    Scopus

    7
    Citation
    (Scopus)
  • A new thin approximation simulation method of screening current in REBCO tape considering tape's thickness

    S. Noguchi, A. Ishiyama, H. Ueda

    2017 IEEE International Magnetics Conference, INTERMAG 2017    2017.08

     View Summary

    An extremely high field homogeneity is required for applications of NMR and MRI magnets.

    DOI

    Scopus

  • Numerical Investigation of Metal Insulation Technique on Turn-to-Turn Contact Resistance of REBCO Pancake Coils

    So Noguchi, Ryosuke Miyao, Katsutoshi Monma, Hajime Igarashi, Atsushi Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   27 ( 4 )  2017.06  [Refereed]

     View Summary

    No-insulation (NI) REBCO pancake coils show high thermal stability, however the charging delay is an issue. Hence, to improve the charging delay, it was proposed that a stainless steel (SUS) tape was cowound between turns, called "metal-as-insulation" or "metal-insulation (MI)," to increase the turn-to-turn contact resistivity. The MI technique could make the turn-to-turn contact resistivity approximately 50 times large compared to a conventional NI REBCO pancake coil. This paper reports a bypass current behavior on the cross section of MI REBCO pancake coil using two-dimensional finite element method. The influence of the SUS tape thickness, the MI material, and the number of SUS tapes on the turn-to-turn contact resistivity is investigated. As the result, it is clarified that the turn-to-turn contact resistivity strongly depends on the surface condition and number of SUS tapes.

    DOI

    Scopus

    12
    Citation
    (Scopus)
  • Influence of the Turn-to-Turn Contact Electrical Resistance on the Thermal Stability in Meter-Class No-Insulation REBCO Pancake Coils During a Local Normal-State Transition

    Kazuki Katsumata, Tao Wang, Atsushi Ishiyama, So Noguchi, Katsutoshi Monma, Shigeo Nagaya, Tomonori Watanabe

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   27 ( 4 )  2017.06  [Refereed]

     View Summary

    Inmagnetic resonance imaging and nuclear magnetic resonance applications, it is important that the high-temperature superconducting coils provide a high magnetic field in a miniaturized form factor. Our research group considers these requirements to be compatiblewith no-insulation (NI) coils in which the thickness of the Cu stabilization layer and the turn-to-turn contact electrical resistance are key parameters that enable both high current densities and high thermal stabilities. When the Cu stabilization layer is thin, the current density is impaired, but the thermal stability is improved. If the turn-to-turn contact electrical resistance is very large, then the characteristics of the NI REBCO coil approach the characteristics of conventional insulated coils, and the thermal stability may be degraded. However, when the turn-to-turn contact electrical resistance is large, the excitation delay time is reduced. In this study, we used a combination of the partial element equivalent circuit method and the finite element method to perform a current distribution and thermal analysis of the behavior of NI REBCO coils when a local normal-state transition occurs. We also considered the appropriate turn-to-turn contact electrical resistance that could shorten the excitation delay time as much as possible while still suppressing the formation of hotspots, which is a disadvantage of the NI REBCO coil.

    DOI

    Scopus

    24
    Citation
    (Scopus)
  • Numerical Evaluation of the Reinforcing Effect of the Advanced YOROI Coil Structure for the HTS Coil

    Yuji Kashiwazaki, Atsushi Ishiyama, Xudong Wang, Hiroshi Ueda, Tomonori Watanabe, Shigeo Nagaya

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   27 ( 4 )  2017.06  [Refereed]

     View Summary

    REBCO coils applied to superconducting magnetic energy storage system, magnetic resonance imaging, medical accelerator, and so on, are expected to result in high efficiency and compactness due to the realization of higher magnetic field and current density. Because these devices require large coil radius, huge hoop stress "BJR" (= magnetic field x current density x coil radius) is produced in the coil winding and the damage to these devices is likely to cause. In our previous study, we proposed a novel coil structure called the Y-based oxide superconductor and reinforcing outer integrated (YOROI) structure to achieve a highstrength REBCO pancake coil. The YOROI structure comprises upper and lower plates and the outer frame of the winding outer periphery. The frames are forcibly expanded by the superconducting coil winding situated inside when the coil winding is subjected to an electromagnetic force. The outer frame is connected to the upper and lower plates and transfers a part of the electromagnetic force from the coil winding to the reinforcing outer plates. The reinforcing outer plates then support the coil to suppress the coil deformation against the electromagnetic forces. The YOROI structure achieved the resistance to a maximum hoop stress of 2 GPa, which was calculated from the BJR in an excitation test at 4.2 K in 8-T backup fields. In this study, we investigated the effect of the stress control structure to realize the HTS coil with a mechanical strength of over 2 GPa using a three-dimensional finite-element structural analysis.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • Temperature and Pressure Distribution Simulations of 3-km-Long High-Temperature Superconducting Power Cable System With Fault Current for 66-kV-Class Transmission Lines

    Tetsuo Yasui, Natsuko Takeda, Yusuke Yokoo, Koh Agatsuma, Atsushi Ishiyama, Xudong Wang, Takato Masuda, Toshiya Morimura, Tomoo Mimura

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   27 ( 4 )  2017.06  [Refereed]

     View Summary

    A computer program has been developed by numerically solving the nonlinear heat conduction and heat transfer equations, which are discretized using the finite difference method, to calculate the temperature and pressure distributions in high-temperature superconducting (HTS) power cables cooled using liquid nitrogen (LN2). The LN2 coolant properties are estimated using Cryodata's GASPAK software package. This evaluation of the temperature and pressure distributions is important to understand how we can make practical use of HTS power cables and to assess the effects of short-circuit accidents. To incorporate HTS power cables into real grids, it is necessary to evaluate HTS power cables that are a few kilometers long. In this study, 3-km-long HTS cables were evaluated using our proposed computer program. This program was used to model the cooling system, ac loss, dielectric loss, and intermediate-joint losses. The results revealed that the temperature of the LN2 coolant at the cable outlet could reach the saturation temperature when a fault current of 31.5 kA flowed for 2 s (worst case for the 66-kV-class transmission lines in Japan). From the results, it was also clear that the effects of the ac loss, dielectric loss, and intermediate-joint losses on the increase in the temperature of the LN2 coolant could not be ignored.

    DOI

    Scopus

    9
    Citation
    (Scopus)
  • Progress in the Development of Conduction-Cooled REBCO Magnets for Ultrahigh-Field MRI Systems

    Hiroshi Miyazaki, Sadanori Iwai, Tatsuro Uto, Yasumi Otani, Masahiko Takahashi, Taizo Tosaka, Kenji Tasaki, Shunji Nomura, Tsutomu Kurusu, Hiroshi Ueda, So Noguchi, Atsushi Ishiyama, Shin-ichi Urayama, Hidenao Fukuyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   27 ( 4 )  2017.06  [Refereed]

     View Summary

    We started developing REBa2Cu3O7-delta (REBCO) magnets for ultrahigh-field magnetic resonance imaging (MRI) systems in 2013. Our final targets are 9.4 TMRI systems for whole-body and brain imaging. In this paper, a conduction-cooled 1.5 T REBCO MRI magnet having a room-temperature bore of 396 mm was fabricated and tested in order to evaluate the magnetic field homogeneity and stability. The magnet was composed of 60 single pancakes whose inner diameter was 500 mm. The total conductor length was 10.3 km, and the total inductance was 12.4 H. The size of the homogeneous magnetic field region was 200 mm diameter spherical volume. The central magnetic field was as high as 1.5 T at 192.7 A, and the current density of single pancakes was 301 A/mm(2). The magnet was cooled from room temperature to 4.7 K in 55 hours, and the temperature difference among the coils was 0.1 K or less during both initial cooling and excitation. The magnetic field inhomogeneity was 249.7 parts per million (ppm), and the Z(2) coefficient was largest at 579.6 ppm. The main reason for the error magnetic field was dimensional errors in the positions on the z-axis. The magnetic field inhomogeneity was improved to 4.1 ppm by passive shimming using iron pieces. The magnetic field stability was about 2 ppm/h because of a reduction in screening-current induced in the REBCO-coated conductors. Current sweep reversal improved the magnetic field stability from 2 ppm/h to 0.8 ppm/h.

    DOI

    Scopus

    17
    Citation
    (Scopus)
  • Screening-Current-Induced Magnetic Field of Conduction-Cooled HTS Magnets Wound With REBCO-Coated Conductors

    Hiroshi Miyazaki, Sadanori Iwai, Tatsuro Uto, Yasumi Otani, Masahiko Takahashi, Taizo Tosaka, Kenji Tasaki, Shunji Nomura, Tsutomu Kurusu, Hiroshi Ueda, So Noguchi, Atsushi Ishiyama, Shin-Ichi Urayama, Hidenao Fukuyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   27 ( 4 )  2017.06  [Refereed]

     View Summary

    Superconducting magnets for magnetic resonance imaging systems require homogeneous, stable magnetic fields. The homogeneity of the magnetic field is highly dependent on the coils shape and positions. Furthermore, in REBa2Cu3O7-delta (REBCO) magnets, the screening-current-induced magnetic field, which changes the magnetic field distribution of the magnet, is one of the most critical issues. In the work described here, a small REBCO coil that can generate a magnetic field of over 10 T was fabricated and tested. The small REBCO coil was composed of a stack of 22 single pancake coils whose inner and outer diameters were 50 mm and 130 mm, respectively. The total conductor length was 1.5 km. The small REBCO coil could generate a central magnetic field of 8.27 T at 10 K. A magnetic field of over 10 T was achieved by replacing 12 of the single pancake coils with new ones wound with the latest REBCO-coated conductors. The measured value of the central magnetic field at 10 K was 13.53 T, which was lower than the calculated value of 13.94 T obtained without taking account of the screening-current-induced magnetic field. Furthermore, it was examined whether the current sweep reversal would be effective for 10 T-class magnetic field conditions.

    DOI

    Scopus

    19
    Citation
    (Scopus)
  • Numerical Evaluation on Irregular Field Generated by Screening Current in High-Field REBCO Coil for Whole-Body MRI

    Kohei Nakazono, Hiroshi Ueda, Atsushi Ishiyama, So Noguchi, Hiroshi Miyazaki, Taizo Tosaka, Tsutomu Kurusu, Shunji Nomura, Shinichi Urayama, Hidenao Fukuyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   27 ( 4 )  2017.06  [Refereed]

     View Summary

    In recent years, high-field magnets wound with RE-BCO tape and their applications to magnetic resonance imaging (MRI) have undergone considerable research and development. MRI coil systems require a highly accurate field in the imaging space. However, in REBCO coils, the irregular magnetic field generated by the screening current is induced by the radial component of the magnetic field in the REBCO tape, and may deteriorate the field quality both spatially and temporally. Therefore, a design process with consideration for the effect of the screening-current field is required for the reduction and correction of this field for a high-accuracy-field REBCO coil. In this study, the screening-current distribution in the REBCO tape and the irregular magnetic field were analyzed by using the simulation we developed for a REBCO model coil system for whole-body MRI. We additionally discuss the effect of the screening-current field in the REBCO coil based on the coil shape and arrangement to use it as feedback to the design stage.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Progress of Yoroi-Coil Structure in Mechanical Strength with High Current Density

    Tomonori Watanabe, Shigeo Nagaya, Naoki Hirano, Satoshi Awaji, Hidetoshi Oguro, Atsushi Ishiyama, Masaki Hojo, Masaaki Nishikawa

    IEEE Transactions on Applied Superconductivity   27 ( 4 )  2017.06  [Refereed]

     View Summary

    Yoroi-coil (Y-based oxide superconductor and reinforcing outer integrated coil) structure has been developed to fabricate very strong pancake coils against electromagnetic force. In Yoroi-coil structure, the outer supporting structure is effective to make a mechanically robust coil having a high current density in the case that the hoop stress must exceed the yield strength of a REBCO-coated conductor without this reinforcement. By the experiments and analysis, we pointed out that the remarkably weak delamination stress can cause the delamination of the coated conductor in coils. So that Yoroi-coil structure has advantages to delamination because it could maintain a coil shape with reinforcing materials, without impregnation. Since higher current density is required by various applications, the Yoroi-coil using austenitic stainless steel reinforcing frames and plates, has been verified by the hoop stress test with high current density. Then, high coil current density of 446 A/mm2 was achieved by the Yoroi-coil-structured double pancake (DP) coil, with the total number of the winding turns of 574, at 4.2 K in the back-up magnetic field of 11 T. The inner and outer diameters of the DP coil were 190 and 250.1 mm, respectively. Although the hoop stress evaluated on the assumption of excluding the supporting structure exceeds 1 GPa, Yoroi-coil structure restricted the strain of coil winding ranging 0.2% to 0.3%. The stainless steel reinforcing member well supported a part of electromagnetic force in Yoroi-coil structure, even with high coil current density.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Temperature and Pressure Simulations of 66 kV 40 m HTS Cable System in Short-Circuit Current Accidents Compared With Experimental Results

    Natsuko Takeda, Tetsuo Yasui, Yusuke Yokoo, Koh Agatsuma, Atsushi Ishiyama, Xudong Wang, Takato Masuda, Toshiya Morimura, Tomoo Mimura

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   27 ( 4 )  2017.06  [Refereed]

     View Summary

    A numerical analysis program has been developed to simulate the transient temperature and pressure distribution in an high-temperature superconducting (HTS) power cable cooled by a forced flow of subcooled LN2 during a short-circuit current accident. This computer simulation program includes computations of temperature and pressure profiles not only in the HTS power cable itself, but also in the cooling system, including the circulation pump. In 2015, Sumitomo Electric Industries demonstrated a 66 kV 40 m model cable with a fault current test, during which the void between the copper conductors of the copper former was filled by insulation material. In this study, simulations of themodel cable were performed by considering that LN2 is not absorbed in the copper former. This simulation was found to more precisely match experimental data by considering the rise in LN2 temperature at the inlet and transient value of the thermal conductivity of the dielectric layer.

    DOI

    Scopus

    4
    Citation
    (Scopus)
  • Current Behavior Simulation in Stacked NI REBCO Pancake Coils during Local Normal-State Transition

    So Noguchi, Ryosuke Miyao, Katsutoshi Monma, Hajime Igarashi, Hiroshi Ueda, Atsushi Ishiyama

    IEEE Transactions on Applied Superconductivity   27 ( 4 )  2017.06  [Refereed]

     View Summary

    This paper presents the current behavior and axial Lorenz force of stacked no-insulation (NI) REBa2Cu3O7-x (REBCO, RE = Rare Earth) double-pancake coils during local normal-state transition. The NI winding technique enhances the thermal stability and increases the engineering current density in REBCO pancake coils. The high thermal stability of NI REBCO coil has been verified in experiments of overcurrent test. In addition, the numerical simulations of NI REBCO single-pancake coils have been performed to confirm the high stability. However, REBCO magnets usually consist of some stacked double-pancake coils to generate a high magnetic field for practical applications. When a normal-state transition occurs in one of the stacked pancake coils, it may affect the other pancake coils. For the more reliable verification, the current and electromagnetic force behavior of stacked NI REBCO pancake coils during a normal-state transition should be simulated. To examine the stacked NI REBCO pancake coils, we extend the previously proposed partial element equivalent circuit (PEEC) model to deal with a few double-pancake coils. In this paper, an NI REBCO double-pancake coil and their three stacked coils are simulated by using the extended PEEC model.

    DOI

    Scopus

    12
    Citation
    (Scopus)
  • Detection Method for a Local Normal-State Transition in a No-Insulation REBCO Pancake Coil

    Tao Wang, Kazuki Katsumata, Atsushi Ishiyama, So Noguchi

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   27 ( 4 )  2017.06  [Refereed]

     View Summary

    In this paper, we have proposed a detection method for detecting and locating a local normal-state transition in a meter-class no-insulation (NI) coil that is deployed in next-generation high-field magnetic resonance imaging scanners (MRIs), using a copper pickup coil. There are two schemes for detecting and locating the normal zone: one is a ring pickup coil assembled on the midplane of a central bore and the other consists of several sector pickup coils deployed on the coil winding, namely "scanning pickup coil." To verify the effectiveness of these detection methods, we performed a numerical simulation coupling consisting of a partial element equivalent circuit, a thermal analysis, and a magnetic field analysis. Based on the results of analyses, we reproduced the distributions of the temporal variations of the magnetic flux in the central bore and on the coil winding of the meter-class NI coil, and discussed the effectiveness of these pickup coil schemes for detecting and locating a local normal-state transition in a meter-class NI coil used in next-generation high-field MRIs.

    DOI

    Scopus

    4
    Citation
    (Scopus)
  • Safety and Reliability of 66-kV Class HTS Cable Systems in Short-Circuit Current Accidents-Experimental Results on 40-m Cable System

    Takato Masuda, Toshiya Morimura, Tetsutaro Nakano, Osamu Maruyama, Tomoo Mimura, Tetsuo Yasui, Koh Agatsuma, Atsushi Ishiyama

    IEEE Transactions on Applied Superconductivity   27 ( 4 )  2017.06  [Refereed]

     View Summary

    High-temperature superconducting (HTS) cables can transmit large amounts of electricity in a compact size with minimal losses. Therefore, it expects to save the construction cost of underground lines in urban areas and decrease transmission losses. The stability and reliability of HTS cable systems in normal operation has been verified by real grid interconnection tests around the world. While general practical use of HTS cable systems requires the verification of their stability not only in normal operation but also in the event of various accidents (ground fault, short-circuit current, liquid nitrogen leakage, etc.) and understanding these phenomena and their impact. However, a few studies have been conducted to investigate the safety of HTS cable systems in the event of the accidents so far. Regarding the short-circuit current, the maximum current depends on the voltage class and grid conditions, and it was set as 31.5 kA for the 66 kV systems in Japan. In order to verify the phenomena and impact to the cable systems, a 40-m cable system was constructed and cooled by circulated subcooled liquid nitrogen (LN2). After the initial critical current (Ic) measurement of the cable system, the short-circuit current tests were conducted with ac 28.5 kA for 0.6 s and 16 kA for 8.4 s. The former testing condition is almost simulated as the current of 31.5 kA and the latter one is as equivalent heat generation in the HTS cable to 31.5 kA for 2 s. As the initial state of LN2, temperature and pressure of the cable inlet were around 68 K and 0.26 MPaG. The measured temperature and pressure rises of the coolant were not so high to make some damage to the HTS cable. After these tests, the cable Ic was measured again and no damage was found.

    DOI

    Scopus

    13
    Citation
    (Scopus)
  • Temperature Simulation of a 20 m HTS Power Model Cable System in a Fault Current for 275 kV Transmission Lines

    Yusuke Yokoo, Tetsuo Yasui, Natsuo Takeda, Koh Agatsuma, Atsushi Ishiyama, Xudong Wang, Masashi Yagi, Tomohiro Takagi

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   27 ( 4 )  2017.06  [Refereed]

     View Summary

    A simulation has been developed for estimating the transient temperature and pressure distributions in a high-temperature superconducting (HTS) power cable with a fault current accident cooled by a forced flow of subcooled liquid nitrogen (LN2). This simulation is an essential tool for realizing a practical HTS power cable in order to assess the effects of shortcircuit accidents. When a fault occurs in a 275 kV class power transmission system in Japan, an excessive current of 63 kA may flow in the cable for 0.6 s. When faults occur, it is important to estimate the temperature and pressure profiles in a cable cooled by the forced flow of subcooled LN2. The temperature profiles of the LN2 coolant and the cable cores were analyzed by solving nonlinear partial differential equations of the heat transfer phenomenon through heat conduction using finite-differencemethod. The GASPAK software package (Cryodata) was used to evaluate the fluid properties. The simulation results for 275 kV class 20 m model cable show fairly good agreement with the experimental results obtained by Fukukawa Electric.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Feature: “Development of Fundamental Technologies for HTS Coils” and “Development of Medical Devicand Systems for Advanced Medical Services”

    MIYAZAKI Hiroshi, ISHIYAMA Atsushi

    TEION KOGAKU (Journal of Cryogenics and Superconductivity Society of Japan)   52 ( 4 ) 216 - 216  2017

    DOI CiNii

  • Extracting the Values of Resting-state Functional Connectivity that Correlate with a Tendency of Internet Addiction

    IZAWA Shun, TACHIKAWA Kenta, ONO Yumie, KOBAYASHI Hiroshi, KURIKI Shinya, ISHIYAMA Atsushi

    Transactions of Japanese Society for Medical and Biological Engineering   55 ( 1 ) 39 - 44  2017

     View Summary

    <p>The number of patients with internet addiction disorder (IAD), especially among school-age children, is on the rise. Development of objective examination technique to assist the current diagnostic methods using medical interview and inquiry tests is desirable for detection of IAD at its early stage. In this study, we extracted the values of functional connectivity (FC) that correlated with a tendency of IAD, using resting-state functional magnetic resonance imaging (rs-fMRI) data. We recruited 40 males [mean age (SD): 21.9 (0.9) years] with no neurological disorders, conducted rs-fMRI recordings for 7 min 30 s, and administered five questionnaires including internet addiction test (IAT), to assess their mental states. The IAT scores of all participants were in the range of healthy to a tendency of IAD. The FC values were calculated using the cross-correlation of time-series signals in a low frequency band (0.017 to 0.09Hz) between all possible connections of brain region pairs defined by Automated Anatomical Labeling (AAL). For each region pair, we calculated Pearson's correlation coefficients "γ" between the FC values and the scores of IAT as well as other inventories for psychological states, in all subjects. The "γ" were subjects-cross-validated, and the FC of the survived region pairs were statistically assessed by correction of multiple comparison. Finally, we obtained some region pairs in which FC specifically correlated with the IAT scores, but not with other psychological scores. These pairs had mostly negative "γ" over long-distance connections across right and left brain hemispheres. The results suggested that the functional connectivity between specific brain regions was significantly degraded already at the stage prior to the onset of IAD. We expect that our connectivity method can be an objective tool for detecting a tendency of IAD to assist the present diagnostic methods.</p>

  • Design of a conduction-cooled 9.4T REBCO magnet for whole-body MRI systems

    Hiroshi Miyazaki, Sadanori Iwai, Yasumi Otani, Masahiko Takahashi, Taizo Tosaka, Kenji Tasaki, Shunji Nomura, Tsutomu Kurusu, Hiroshi Ueda, So Noguchi, Atsushi Ishiyama, Shinichi Urayama, Hidenao Fukuyama

    SUPERCONDUCTOR SCIENCE & TECHNOLOGY   29 ( 10 ) 104001  2016.10  [Refereed]

     View Summary

    A project on the development of REBa2Cu3O7-delta (REBCO) magnets for ultra-high-field magnetic resonance imaging (MRI) was started in 2013. Since REBCO-coated conductors feature high mechanical strength under tensile stress and high critical current density, use of REBCO coils would allow superconducting magnets to be made smaller and lighter than conventional ones. In addition, a conduction-cooled superconducting magnet is simpler to use than one cooled by a liquid helium bath because the operation and maintenance of the cryogenic system become simpler, without the need to handle cryogenic fluid. Superconducting magnets for MRI require homogeneous, stable magnetic fields. The homogeneity of the magnetic field is highly dependent on the coil shape and position. Moreover, in REBCO magnets, the screening-current- induced magnetic field, which changes the magnetic field distribution of the magnet, is one of the critical issues. In order to evaluate the magnetic field homogeneity and the screening-current- induced magnetic field, a 1 T model magnet and some test coils were fabricated. From an evaluation of the 1 T model magnet, it was found that the main reason for magnetic field inhomogeneity was the tolerances in the z-axis positions of the coils, and therefore, it is important to control the gap between the single pancakes. In addition, we have already demonstrated the generation of an 8.27 T central magnetic field at 10 K with a small test coil. The screening-current-induced magnetic field was 0.43 T and was predictable by using an electromagnetic field simulation program. These results were reflected in the design of a conduction-cooled 9.4 T REBCO magnet for whole-body MRI systems. The magnet was composed of six main coils and two active shield coils. The total conductor length was 581 km, and the stored energy was 293 kJ. The field inhomogeneity was 24 ppm peak to peak and 3 ppm volume-root-mean-square (VRMS) for a 500 mm diameter spherical volume (DSV). The axial and radial 5 gauss line locations were less than 5 m and 4.2 m respectively.

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  • Evaluation on Quench Protection for No-Insulation REBCO Pancake Coil

    Oki, Takahiro, Ikeda, Aika, Wang, Tao, Ishiyama, Atsushi, Noguchi, So, Monma, Katsutoshi, Watanabe, Tomonori, Nagaya, Shigeo

    IEEE Transactions on Applied Superconductivity   26 ( 4 )  2016.06  [Refereed]

     View Summary

    © 2002-2011 IEEE.We have been developing a no-insulation (NI) winding technique to be used in both high thermal stability and high current density, which have a tradeoff relationship. This paper presents numerical and experimental studies on the thermal stability of an NI REBCO pancake coil by focusing on a quench protection scheme. In the case of an accident or a local normal-state transition, the power supply for the superconducting coil must be immediately shut down in order to ensure its safety. During the sudden discharging of a conventional insulated winding coil, most of the stored electromagnetic energy is dissipated by an external dump resistor connected across the coil terminals as a quench protection system. However, in an NI pancake coil, current flows in the radial direction in order to bypass the local normal-state area to the adjacent turns. The stored energy in the coil may be dissipated as Joule heat owing to the turn-to-turn contact electrical resistance. In this study, by using experiments and numerical analyses, we evaluated two transient behaviors during sudden discharging: the distribution of energy dissipation and the temperature increase in model NI REBCO pancake coils. We also evaluated the thermal behavior of the NI coil during a local normal transition.

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  • Experiment and Numerical Analysis on the YOROI Structure for High-Strength REBCO Coil

    Wang, Xudong, Tsuji, Yoshiaki, Ishiyama, Atsushi, Yamakawa, Hiroshi, Watanabe, Tomonori, Nagaya, Shigeo

    IEEE Transactions on Applied Superconductivity   26 ( 4 )  2016.06  [Refereed]

     View Summary

    © 2016 IEEE.To achieve a high current density and a compact REBCO coil, a reinforcing structure is essential to prevent coil degradation and deformation caused by the large Lorentz force. A new reinforcing structure for the REBCO coil called the Y-based oxide superconductor and reinforcing outer integrated (YOROI) coil was proposed in the previous study. The YOROI coil, which exhibited no degradation after an excitation test with a maximum hoop stress of 1.7 GPa at 4.2 K in 8-T backup fields, has great ability to reduce the stress and strain acting on the coil winding to maintain the coil shape and prevent degradation in the REBCO wire. In this study, the hoop stress in the winding and the stress shared by the reinforcing structure of a YOROI model coil were measured at 40 K in 10-T backup fields to clarify the reinforcing mechanism of the YOROI coil. A three-dimensional structural analysis, which simulated the experimental condition, was performed on the model coil to determine the distribution of stress and strain in the winding and reinforcing structure.

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  • Transient Behaviors of No-Insulation REBCO Pancake Coil during Local Normal-State Transition

    Ikeda, Aika, Oki, Takahiro, Wang, Tao, Ishiyama, Atsushi, Monma, Katsutoshi, Noguchi, So, Watanabe, Tomonori, Nagaya, Shigeo

    IEEE Transactions on Applied Superconductivity   26 ( 4 )  2016.06  [Refereed]

     View Summary

    © 2015 IEEE.Recently, no-insulation (NI) winding techniques have been proposed for achieving high current density and high thermal stability. To verify the excellent characteristics achieved using these techniques, we investigated the transient behaviors of NI REBCO pancake coils. In this paper, we evaluate transient electromagnetic and thermal behaviors during a local normal-state transition, based on a partial element equivalent circuit and thermal coupled numerical analysis. Moreover, we investigate temporal and spatial current distributions in the NI coil winding after a local normal transition occurs. We also clarify the reason for the suppression of temperature increase caused by the local normal-state transition in the NI winding. Subsequently, we evaluate the influence of the thickness of a Cu stabilizer on the thermal stability of the NI and conventional insulation windings. Finally, we discuss the mechanism of high thermal stability attained in the NI coil winding technique.

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  • Experimental Results of Screening-Current Field With 10-T Class Small REBCO Coil

    S. Iwai, H. Miyazaki, Y. Ohtani, T. Tosaka, K. Tasaki, S. Nomura, T. Kurusu, H. Ueda, S. Noguchi, A. Ishiyama, S. Urayama, H. Fukuyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   26 ( 4 )  2016.06  [Refereed]

     View Summary

    A REBCO-coated conductor has a tape shape and is suitable for forming a stack of single pancakes for generating a high magnetic field. However, the magnetic flux going through the tape surface causes a screening current, which reduces the magnetic field in conventional coil designs. Magnetic resonance imaging systems need high uniformity of the magnetic field, both spatially and temporally, and thus, the screening field resulting from the screening current is one of the critical issues. In this paper, a 10-T class small test coil using REBCO-coated conductors was fabricated and tested in a conduction-cooled configuration from 10 to 60 K for investigating the effect of the screening field on the generated magnetic field in the inner space of the coil. The coil was composed of a stack of 22 single pancakes using 4-mm-wide REBCO tapes with an inner diameter of 50 mm, an outer diameter of 129 mm, and a height of 104 mm. For different stacking orders based on the coil critical currents, the measured values of the central magnetic field at 10 K were 7.66 and 8.27 T, which were lower than the calculated values of 8.07 and 8.70 T obtained without taking account of the screening-current fields.

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  • Experiment and Simulation of Impregnated No-Insulation REBCO Pancake Coil

    So Noguchi, Katsutoshi Monma, Sadanori Iwai, Hiroshi Miyazaki, Taizo Tosaka, Shunji Nomura, Tsutomu Kurusu, Hiroshi Ueda, Atsushi Ishiyama, Shinichi Urayama, Hidenao Fukuyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   26 ( 4 ) 4601305  2016.06  [Refereed]

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    It is important to investigate the stability and behavior of an epoxy-resin-impregnated no-insulation (NI) REBCO pancake coil to implement high-field applications, such as ultra-high-field magnetic resonance imaging. We have performed sudden discharging and overcurrent tests for the impregnated NI REBCO pancake coil. From the discharging test, the contact resistivity is estimated, and it changes depending on the initial current. From the overcurrent test, the high thermal stability of the impregnated NI REBCO pancake coil is confirmed. The REBCO pancake coil is charged up to 67 A though the critical current is only 46 A, and no degradation has been found. To investigate in detail the electromagnetic behavior of an impregnated NI REBCO pancake coil, the simulation is performed by means of the partial element equivalent circuit (PEEC) model. In the sudden discharging test, the simulation results for the case of lower initial current are in good agreement with the experimental data. As can be inferred from the simulation results, the current drastically decreases from the inside of the impregnated NI REBCO pancake coil. The result of the overcurrent simulation is almost identical to the experimental one. However, since the contact resistivity is presumed to be constant in the simulation, the difference is observed in the high current region.

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  • Evaluation of Irregular Magnetic Field Generated by Screening Current in REBCO Coils for High Accuracy Field

    Ayako Matsumi, Hiroshi Ueda, So Noguchi, Tao Wang, Atsushi Ishiyama, Hiroshi Miyazaki, Taizo Tosaka, Shunji Nomura, Tsutomu Kurusu, Shinichi Urayama, Hidenao Fukuyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   26 ( 4 ) 4702305  2016.06  [Refereed]

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    In recent years, research and development of applications for a high field magnet wound with a REBCO tape into nuclear magnetic resonance and magnetic resonance imaging have been carried out. These applications require a very high accuracy field, that is, the spatial uniform and temporally stable field. However, in the REBCO coils, the irregular magnetic field is generated by the screening current, which is remarkably induced by the radial component of the magnetic field in a REBCO tape. Therefore, a nonconventional approach is required for the reduction or correction of the irregular magnetic field generated by the screening current in the stage of design for a high-accuracy-field REBCO coil. The prediction and improvement of the irregular magnetic field generated by the screening current is a serious issue for the development and design of REBCO coils and correction shims. In this study, we numerically investigated the screening current distribution in the winding and the irregular magnetic field generated by the screening current. Moreover, we discuss the irregular effect of the magnetic field generated by the screening current in the REBCO coil from the arrangement of the coil windings and excitation pattern.

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  • Evaluation of Magnetic Field Distribution by Screening Current in Multiple REBCO Coils

    Ayumu Mochida, Hiroshi Ueda, So Noguchi, Tao Wang, Atsushi Ishiyama, Hiroshi Miyazaki, Taizo Tosaka, Shunji Nomura, Tsutomu Kurusu, Shinichi Urayama, Hidenao Fukuyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   26 ( 4 ) 4702805  2016.06  [Refereed]

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    Coil systems are fabricated with various combinations of multiple coils in order to generate homogenous fields for NMR and MRI applications. In multiple coil systems using REBCO coils, the behavior of the screening current, which deteriorates field homogeneity, depends on the patterns of the transport current, the charging sequence of the coils, and the various resulting magnetic fields. It is therefore important to investigate and clarify the behavior of the irregular magnetic field and screening current in multiple coil systems under different operating environments. In a previous study, we experimentally and numerically clarified the different behaviors of irregular magnetic fields based on the charging sequence of coils in multiple-model REBCO coils [1], [2]. In this paper, we constructed the multiple-model REBCO coils in order to obtain the fundamental data for reducing or improving the resulting irregular magnetic field. Furthermore, the distribution of the irregular magnetic field in terms of the screening current was measured by using the reversal current method [3], [4]. We also calculated the spatial and temporal behavior of the irregular magnetic field by using our developed 3-D numerical simulation. Based on the experimental and numerical results, we discuss the behavior of the magnetic field in terms of the screening current when using the current sweep reversal method in multiple-model REBCO coils.

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  • Numerical Simulation on Magnetic Field Generated by Screening Current in 10-T-Class REBCO Coil

    Hiroshi Ueda, Yohei Imaichi, Tao Wang, Atsushi Ishiyama, So Noguchi, Sadanori Iwai, Hiroshi Miyazaki, Taizo Tosaka, Shunji Nomura, Tsutomu Kurusu, Shinichi Urayama, Hidenao Fukuyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   26 ( 4 ) 4701205  2016.06  [Refereed]

     View Summary

    In a REBCO superconducting magnet for magnetic resonance imaging (MRI) applications, the large screening current induced by a magnetic field perpendicular to the winding tape is a serious problem: it generates irregular magnetic field that deteriorates the spatial field homogeneity and temporal field stability in MRI applications. Therefore, we need to estimate the magnetic field generated by the screening current using electromagnetic field analysis to design and develop a REBCO magnet that generates highly accurate and stable magnetic field. Therefore, to examine the influence of the magnetic field generated by the screening current, we constructed cryocooler-cooled small bore-coil stacked pancake REBCO coils with an inner diameter of 50 mm. This coil generates a magnetic field of 10 T at the center. In this study, we report the evaluation of the current distribution and magnetic field in the REBCO coil using the developed 3-D numerical simulation code for electromagnetic field analysis in a REBCO tape using the finite-element method and fast multipole method. The numerical results agree well with the experimental results. Furthermore, we discuss the current distribution in the REBCO tape and the spatial and temporal behavior of the magnetic field on the basis of the results of the experiments and numerical simulation.

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  • R&D Project on HTS Magnets for Ultrahigh-Field MRI Systems

    Taizo Tosaka, Hiroshi Miyazaki, Sadanori Iwai, Yasumi Otani, Masahiko Takahashi, Kenji Tasaki, Shunji Nomura, Tsutomu Kurusu, Hiroshi Ueda, So Noguchi, Atsushi Ishiyama, Shinichi Urayama, Hidenao Fukuyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   26 ( 4 ) 4402505  2016.06  [Refereed]

     View Summary

    An R&D project on high-temperature superconducting (HTS) magnets using (RE) Ba2Cu3O7 (REBCO; RE = rare earth) wires for ultrahigh-field (UHF) magnetic resonance imaging (MRI) systems is described. Our targets are 9.4-T MRI systems for whole-body imaging and brain imaging. REBCO wires are promising components for UHF-MRI because REBCO wires have high critical current density in high magnetic fields and high strength against hoop stresses, which allows MRI magnets to be smaller and lighter than conventional ones. The aim of the project is to establish basic magnet technologies for adapting REBCO coils for UHF-MRI. The project term is three years, and this year is the final year. We have already demonstrated the generation of an 8.27-T magnetic field with a small test coil composed of 22 REBCO pancake coils. A magnetic field spatial distribution with inhomogeneity of several hundreds of parts permillion within 100-mm diameter spherical volume (DSV) was demonstrated with a 1-T model magnet. A stable magnetic field of a few parts per million per hour was also demonstrated with the 1-T model magnet. The targets of the project, to be achieved by March 2016, are to demonstrate the generation of a 9.4-T field with the small REBCO coil, and to demonstrate a homogeneous magnetic field in 200-mm DSV with a 1.5-T magnet having three pairs of split coils. Imaging will be performed with the 1.5-T magnet.

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  • Temperature and pressure simulation of a 1.5-km HTS power cable cooled by Subcooled LN<inf>2</inf> with a fault current

    Yasui, Tetsuo, Sato, Yusuke, Agatsuma, Koh, Ishiyama, Atsushi, Wang, Xudong, Wang, Xudong, Ohya, Masayoshi, Masuda, Takato, Honjo, Shoichi

    IEEE Transactions on Applied Superconductivity   26 ( 3 )  2016.04  [Refereed]

     View Summary

    © 2002-2011 IEEE.Waseda University has developed computer programs to estimate the transient temperature and pressure distributions in a high-temperature superconducting (HTS) power cable cooled by a forced flow of subcooled LN2. This simulation is crucial for realizing a practical HTS power cable to assess the effects of short-circuit accidents. When a short-circuit accident occurs, a fault current of 31.5 kA with a duration of 2 s may flow in a cable in the worst case, which is the Japanese criterion for a 66-kV transmission line. The temperature profiles of the LN2 coolant and cable cores were analyzed by solving the heat conduction and heat transfer equations using a finite-difference method. The pressure profiles of the LN2 coolant were calculated using Fanning's equation. For practical use, it was assumed that HTS cables that are a few kilometers long will be adopted. In this study, an evaluation of the stability of a 1.5-km HTS cable with a fault current of 31.5 kA over 2.0 s was performed using our computer program. According to the results, the temperature of the LN2 coolant at the outlet reached the saturation temperature after the fault, and vaporization suddenly occurred. The evaporated gas was released from the outlet to the terminal.

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  • Investigation of Current Flow between Turns of NI REBCO Pancake Coil by 2-D Finite-Element Method

    Noguchi, So, Monma, Katsutoshi, Igarashi, Hajime, Ishiyama, Atsushi

    IEEE Transactions on Applied Superconductivity   26 ( 3 )  2016.04  [Refereed]

     View Summary

    © 2002-2011 IEEE.The no-insulation (NI) winding technique for an NI ReBCO pancake coil is expected to improve dynamic and thermal stability and enhance current density. The investigations on electromagnetic and thermal behaviors are important for the development of NI ReBCO coils. Many stability investigations of the NI ReBCO coil itself have been carried out by experiments and simulations. However, the detailed behavior of the bypass current between turns has not been shown. Although contact resistivity was obtained through prior experiment, it included the resistivity of not only contact surface but also the components, i.e., the copper stabilizer and the Hastelloy substrate, of a ReBCO tape. To investigate the detailed bypass current behavior in this paper, the true contact surface resistivity is taken into account in the simulation. The bypass current on the cross section of the NI ReBCO tape is simulated using the two-dimensional finite-element method. From the simulation results, the influence of the coil-radial resistivity between turns on the turn-to-turn contact surface resistivity is clarified. In addition, the heat loss is also reported, and a simple equivalent circuit of the turn-to-turn contact is proposed.

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  • Development of Evaluation Procedure for Superconductivity of CIC Conductor for Fusion Reactor

    Hideki Kajitani, Atsushi Ishiyama, Kou Agatsuma, Haruyuki Murakami, Norikiyo Koizumi

    TEION KOGAKU (Journal of Cryogenics and Superconductivity Society of Japan)   51 ( 3 ) 71 - 78  2016.04  [Refereed]

     View Summary

    A cable-in-conduit (CIC) conductor using an Nb3Sn strand is applied to the ITER TF coil. The performance of CIC conductor was degraded due to electromagnetic force. This is because a strand in the conductor is subjected to periodically bending strain by electromagnetic force, which causes the performance to become degraded. Strands in the conductor touch each other in a complicated manner due to twisting and the electromagnetic force is transferred via another strand, which leads to complication of bending strain distribution in the conductor. The complicated bending strain distribution makes it difficult to simulate the conductor performance analytically. The author thus developed a new model to evaluate conductor performance using a periodically bent strand model developed in a past study. However, the calculated result showed some error when compared to actual measured results. This may be due to the difference of physical phenomenon between a single freely bent strand and a strand constricted by an adjacent strand in the conductor. The author thus redeveloped a calculation model taking this effect into account. As a result, conductor performance can be successfully simulated. This indicates that a more practical solution can be achieved in quantitative evaluation of conductor performance.

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  • Evaluation of Magnetic Field Homogeneity of a Conduction-Cooled REBCO Magnet With a Room-Temperature Bore of 200 mm

    H. Miyazaki, S. Iwai, Y. Otani, M. Takahashi, T. Tosaka, K. Tasaki, S. Nomura, T. Kurusu, H. Ueda, S. Noguchi, A. Ishiyama, S. Urayama, H. Fukuyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   26 ( 3 )  2016.04  [Refereed]

     View Summary

    Development of a high-temperature superconducting magnet wound with REBa2Cu3O7-delta (REBCO)-coated conductor for ultrahigh-field magnetic resonance imaging (MRI) is in progress. Our final targets are 9.4-T MRI systems for whole-body and brain imaging. Since REBCO-coated conductors feature high mechanical strength under a tensile stress and high critical current density, superconducting magnets could be made smaller by using REBCO coils. Superconducting magnets for MRI require homogeneous stable magnetic fields. The homogeneity of the magnetic field is highly dependent on the size and current density of the coils. Furthermore, in REBCO magnets, the screening-currentinduced magnetic field that changes the magnetic field distribution of the magnet is one of the critical issues. In order to evaluate the magnetic field homogeneity and the screening-current-induced magnetic field of REBCO magnets, a conduction-cooled REBCO magnet with a room-temperature bore of 200 mm was fabricated and tested. The REBCO coils were composed of 12 single pancakes, and the size of the homogeneous magnetic field region was 100-mm diameter spherical volume (DSV). The central magnetic field was as high as 1 T at 285 A. The magnetic field distribution on the z-axis was measured by using an NMR probe. The maximum error magnetic field was 470 parts per million (ppm) in the range from -50 to +50 mm, as well as in the coefficients of the spherical harmonic expansion for a 100-mm DSV. The error magnetic fields due to the screening-current-induced magnetic field were less than 5 ppm, because there was a sufficient distance between the coil and the homogeneous magnetic field region. The main reason for the error magnetic field was dimensional errors in the outer diameters and positions on the z-axis.

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  • Development of Evaluation Procedure for Critical Current of Periodically Bent Nb3Sn Strand

    Hideki Kajitani, Atsushi Ishiyama, Kou Agatsuma, Haruyuki Murakami, Norikiyo Koizumi

      50 ( 12 ) 608 - 615  2016.02  [Refereed]

     View Summary

    A cable-in-conduit (CIC) conductor using Nb3Sn strand is applied to an ITER TF coil. The Nb3Sn strand in the conductor is periodically bent due to electromagnetic force, which causes degradation of performance. This degradation should be evaluated to predict conductor critical current performance. In a past study, a numerical simulation model was developed to evaluate the superconductivity of a periodically bent single strand. However, this model is not suitable for application to strands in the conductor because of the extensive calculation time required. The author thus developed a new analytical model with a much shorter calculation time to evaluate the performance of periodically bent strand. This new model uses the classical model concept of a high transverse resistance model (HTRM). The calculated results show good agreement with the test results of a periodically bent Nb3Sn strand in a ends fixed beam model while there was little error in the uniformly bent model under high transverse load due to the difference in bending moment distribution between the two models. However, for both cases, the newly developed model has a much shorter calculation time than that required for numerical simulation. This indicates that a more practical solution can be achieved when evaluating the performance of periodically bent strands. Thus, the model developed in this study can be applied to evaluation of the performance of conductor incorporating many strands.

  • Optimal Configuration Design of MRI REBCO Magnet Taking into Account Superconducting Layer

    So Noguchi, Hiroshi Miyazaki, Taizo Tosaka, Shunji Nomura, Tsutomu Kurusu, Hiroshi Ueda, Atsushi Ishiyama, Shinichi Urayama, Hidenao Fukuyama

    2016 IEEE CONFERENCE ON ELECTROMAGNETIC FIELD COMPUTATION (CEFC)    2016  [Refereed]

     View Summary

    The development of ultra-high-field (similar to 10 T magnetic resonance imaging (MRI) device is underway. It is, therefore, required to achieve the extremely high field homogeneity at a magnet design stage, where the field homogeneity is evaluated using the Legendre polynomials. Commonly, it is supposed that the current uniformly flows on the cross section of coils. However, for REBCO magnet, the no-current-flowing region has to be taken into account, such as a copper stabilizer. In addition, the REBCO layer inside REBCO tape is very thin, 1 - 2 mu m, so the current-flowing region is 1/100 of the REBCO tape area. Therefore, it is necessary to consider that the current flows only in the REBCO layer, for accurate evaluation of field homogeneity.

  • Electromagnetic Analysis on Magnetic Field and Current Distribution in High Temperature Superconducting Thin Tape in Coil Winding

    Hiroshi Ueda, SeokBeom Kim, So Noguchi, Atsushi Ishiyama, Hiroshi Miyazaki, Sadanori Iwai, Taizo Tosaka, Shunji Nomura, Tsutomu Kurusu, Shinichi Urayama, Hidenao Fukuyama

    2016 IEEE CONFERENCE ON ELECTROMAGNETIC FIELD COMPUTATION (CEFC)    2016  [Refereed]

     View Summary

    High temperature superconducting (HTS) wires are high aspect ratio cross-section tapes. Therefore, the applications of HTS tapes lead to various problems such as AC loss, nonuniform current, and screening current. In practice, we must investigate the detail of current distribution in HTS tapes using the electromagnetic analysis technique dealing with high aspect ratio tape and nonlinearity of superconductor. We developed the numerical simulation code of electromagnetic field analysis in HTS tape using a finite element method (FEM) and fast multipole method (FMM).

  • R&D Progress of HTS Magnet Project for Ultrahigh-field MRI

    Taizo Tosaka, Hiroshi Miyazaki, Sadanori Iwai, Yasumi Otani, Masahiko Takahashi, Kenji Tasaki, Shunji Nomura, Tsutomu Kurusu, Hiroshi Ueda, So Noguchi, Atsushi Ishiyama, Shinichi Urayama, Hidenao Fukuyama

    PROCEEDINGS OF THE 28TH INTERNATIONAL SYMPOSIUM ON SUPERCONDUCTIVITY (ISS 2015)   81   145 - 148  2016  [Refereed]

     View Summary

    An R&D project on high-temperature superconducting (HTS) magnets using rare-earth Ba2Cu3O7 (REBCO) wires was started in 2013. The project objective is to investigate the feasibility of adapting REBCO magnets to ultrahigh field (UHF) magnetic resonance imaging (MRI) systems. REBCO wires are promising components for UHF-MRI magnets because of their superior superconducting and mechanical properties, which make them smaller and lighter than conventional ones. Moreover, REBCO magnets can be cooled by the conduction-cooling method, making liquid helium unnecessary. In the past two years, some test coils and model magnets have been fabricated and tested. This year is the final year of the project. The goals of the project are: (1) to generate a 9.4 T magnetic field with a small test coil, (2) to generate a homogeneous magnetic field in a 200 mm diameter spherical volume with a 1.5 T model magnet, and (3) to perform imaging with the 1.5 T model magnet. In this paper, the progress of this R&D is described. The knowledge gained through these R&D results will be reflected in the design of 9.4 T MRI magnets for brain and whole body imaging. (C) 2016 Published by Elsevier B.V.

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  • Evaluation of performance to detect default mode network among some algorithms applied to resting-state fMRI data

    Tachikawa, Kenta, Izawa, Shun, Ono, Yumie, Kuriki, Shinya, Ishiyama, Atsushi

    Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS   2015-November   1805 - 1808  2015.11

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    © 2015 IEEE.Significant correlation exists in the blood-oxygen-level-dependent (BOLD) signals of resting-state fMRI across different regions in the brain. These regions form the default mode network (DMN), salience network (SN), sensory networks, and others. Among these, the DMN is widely investigated in relation to various mental diseases. Several analytic methods are available for obtaining the DMN activity from individuals' fMRI time-series signals, but a fully effective method has not yet been established. In the present study, we examined a functional connectivity analysis and three algorithms of blind source separation including independent component analysis, second-order blind identification, and non-negative matrix factorization using a set of resting-state fMRI data measured for twelve young participants. Results showed that the second-order blind identification yielded superior performance for the DMN detection, indicating significant activation in all DMN regions based on statistical parametric maps.

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  • Magnetocardiograms early detection of pulmonary arterial hypertension using inverse problem analysis in rat model

    Yasuda, Shotaro, Higano, Sho, Ishiyama, Atsushi, Ono, Yumie, Kajimura, Ichige, Minamisawa, Susumu

    Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS   2015-November   4475 - 4478  2015.11

     View Summary

    © 2015 IEEE.Utilizing small animal magnetocardiograms (MCG), we have developed a diagnostic method to detect the development of pulmonary hypertension (PH) in a rat heart. We obtained multiple MCG of rats with monocrotaline-induced PH and monitored the development of pathophysiological conditions. Current dipole estimation was then applied to determine the association between abnormal propagation of the cardiac excited wavefront and disease states. The progress of right ventricular hypertrophy correlated with a decrease in the angles of the current dipoles during R and S waves. In addition, clear changes in the current dipole angles during S waves were observed 9-19 days before the availability of echocardiographic diagnosis of the PH. Our results showed, using a rat PH model, that continuous monitoring of myocardial conditions allows PH to be detected at an earlier stage than echocardiographic screening.

    DOI

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  • Temperature and pressure simulation of a high-temperature superconducting cable cooled by subcooled LN2 with fault current

    Sato, Yusuke, Agatsuma, Koh, Wang, Xudong, Wang, Xudong, Ishiyama, Atsushi

    IEEE Transactions on Applied Superconductivity   25 ( 3 )  2015.06  [Refereed]

     View Summary

    © 2002-2011 IEEE. A computer simulation has been developed to estimate the transient temperature and pressure distributions in a high-temperature superconducting (HTS) power cable cooled by a forced flow of subcooled LN2. This simulation is critical for assessing the effects of short-circuit accidents in practical HTS power cables. When a fault occurs, an excessive current of 31.5 kA may flow in a cable for 2 s, and it is important to understand the temperature and pressure profiles in a cable cooled by the forced flow of LN2 when these faults occur until the disturbance flows out from a cable. The temperature profile of the LN2 coolant and the cable cores was analyzed by solving heat conduction and heat transfer equations using the finite-difference method. The Cryodata GASPAK software package was used to estimate the fluid properties. The simulation results show a fairly good agreement with the experimental results. By employing a new model of the induction refrigeration system and the circulation pump, a small discrepancy is resolved in pressures between simulation and experiment. The analysis results show that the pressure in the cable significantly changes depending on the initial gas volumes in the terminals and the volume of the LN2 gas that evaporates from the copper former in the cable.

    DOI

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    9
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  • Charging behavior in no-insulation REBCO pancake coils

    Wang, Xudong, Wang, Xudong, Wang, Tao, Nakada, Erika, Ishiyama, Atsushi, Itoh, Ryusei, Noguchi, So

    IEEE Transactions on Applied Superconductivity   25 ( 3 )  2015.06  [Refereed]

     View Summary

    © 2002-2011 IEEE. This paper presents analytical studies on the charging characteristics of a no-insulation (NI) REBCO pancake coil. A partial element equivalent circuit (PEEC) model has been developed to evaluate the local current paths in NI REBCO pancake coils. The PEEC model is able to consider the asymmetry of the coil winding, the partial turn-to-turn contact electrical resistance, and the partial self and mutual inductances. The analysis results are compared with previous charging experimental results and simulations using a simplified parallel equivalent circuit (SPEC) model to validate the proposed approach with the PEEC model. To investigate the charging characteristics of a meter-class NI REBCO pancake coil, numerical simulations were performed by using the PEEC and SPEC models as a parameter of the turn-to-turn contact electrical resistance. In addition, the magnetic field in a 3-T NI REBCO coil was calculated by the SPEC model to clarify the charging delay of a practical scale magnet.

    DOI

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    39
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  • Strengthening effect of 'Yoroi-coil structure' against electromagnetic force

    Watanabe, Tomonori, Nagaya, Shigeo, Hirano, Naoki, Awaji, Satoshi, Oguro, Hidetoshi, Tsuchiya, Yuji, Omura, Takuya, Nimori, Shigeki, Shimizu, Tadashi, Ishiyama, Atsushi, Wang, Xudong, Wang, Xudong

    IEEE Transactions on Applied Superconductivity   25 ( 3 )  2015.06  [Refereed]

     View Summary

    © 2002-2011 IEEE. The strengthening of Yoroi-coil (Y-based oxide superconductor and reinforcing outer integrated coil) structure at stronger electromagnetic force was investigated using the Yoroi-coil structured double-pancake coil with higher strength outer plates of carbon-fiber reinforced plastic (C-FRP) than those of glass-FRP. The coil achieved 1.14 kA transporting at 4.2 K in 14-T back-up magnetic field and the superconducting wire was burnt by thermal runaway after that. The calculated maximum hoop stress, based on the BJR (magnetic field × current density × coil radius) calculations, at the hoop stress test reached 2.0 GPa. This value was far exceeding the tensile strength of superconducting wire ranging from 1 to 1.3 GPa; however, the maximum strain of superconducting wire in the test coil was held about 0.5%. Yoroi-coil structure is useful for the applications, which need high magnetic field precision. The strengthening effect of C-FRP outer plates was observed at outer part of the coil, but it did not cover the whole coil body, so that arrangement of reinforcing outer plates could admit of some improvement.

    DOI

    Scopus

    18
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  • Analyses of Transient Behaviors of No-Insulation REBCO Pancake Coils During Sudden Discharging and Overcurrent

    Tao Wang, So Noguchi, Xudong Wang, Issei Arakawa, Katsuhiko Minami, Katsutoshi Monma, Atsushi Ishiyama, Seungyong Hahn, Yukikazu Iwasa

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   25 ( 3 ) 4303409,1-9  2015.06  [Refereed]

     View Summary

    Stability margin of a high-temperature superconducting (HTS) coil is two or three orders of magnitude greater than that of a low-temperature superconducting coil. In recent years, many papers have reported test results of turn-to-turn no-insulation (NI) HTS coils having extremely enhanced thermal stability, such that burnout never occurs in an NI coil, even at an operating current exceeding 2.5 times the critical current. Thus, The main goal of this paper is to clarify transient electromagnetic and thermal behaviors and mechanism of the high thermal stability in an NI REBCO coil. A partial element equivalent circuit (PEEC) model is proposed for the numerical simulation of an NI REBCO coil, which considers a local electrical contact resistance between turns, an I-V characteristic of an REBCO tape, and local self and mutual inductances of the NI REBCO coil. Using the PEEC model, we investigate the influence of the turn-to-turn contact resistance on the transient behavior of the NI REBCO coil during sudden discharging. We also perform thermal conduction analyses with the PEEC model to clarify the transient behavior of an NI REBCO coil during an overcurrent operation.

    DOI

    Scopus

    163
    Citation
    (Scopus)
  • Development of non-circular REBCO pancake coil for high-temperature superconducting cyclotron

    Xudong Wang, Hirotaka Umeda, Atsushi Ishiyama, Masaki Tashiro, Hiroshi Yamakawa, Hiroshi Ueda, Tomonori Watanabe, Shigeo Nagaya

    IEEE Transactions on Applied Superconductivity   25 ( 3 ) 4601904  2015.06  [Refereed]

     View Summary

    A series of feasibility studies are carried out on the applications of a high-temperature superconducting (HTS) magnet system to a heavy-ion accelerator for particle cancer therapy. A novel HTS cyclotron is expected to be more compact and have higher efficiency than a conventional heavy ion synchrotron accelerator. A high current density is required for the HTS magnet to realize a compact HTS cyclotron. Further, a high-strength reinforcing structure is absolutely essential for the HTS magnet owing to the large Lorentz force caused by the high current density to prevent the magnet deformation and maintain the required high accuracy field. In a previous study, a novel coil structure called the Y-based oxide superconductor and reinforcing outer integrated 'YOROI coil' was proposed and tested at 4.2 K in 8-T backup fields. The YOROI model coil exhibited no degradation after the excitation test with a maximum hoop stress of 1.7 GPa determined by the product of the magnetic field, current density, and coil radius. The mechanism of stress sharing between the coil winding and the reinforcing structures of the YOROI coil was numerically determined. In addition, the electromagnetic and mechanical properties of a reinforcing structure based on the YOROI coil for circular REBCO coils assuming part of the HTS cyclotron magnet system was also numerically simulated in the previous paper. In this study, a new reinforcing structure is proposed on the basis of the YOROI coil for a non-circular REBCO coil assuming part of the HTS cyclotron magnet system. The electromagnetic and mechanical properties for the new reinforcing structure are numerically determined. As a result, the proposed reinforcing structure has great ability to reduce the stress and strain acting on the coil winding to maintain the coil shape and prevent degradation in the REBCO wire.

    DOI

    Scopus

    9
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  • Evaluation of magnetic-field distribution by screening current in multiple REBCO coils

    Hiroshi Ueda, Atsushi Ishiyama, Yuta Ariya, Tao Wang, Xudong Wang, Koh Agatsuma, Hiroshi Miyazaki, Taizo Tosaka, Shunji Nomura, Tsutomu Kurusu, Shinichi Urayama, Hidenao Fukuyama

    IEEE Transactions on Applied Superconductivity   25 ( 3 ) 4700705  2015.06  [Refereed]

     View Summary

    In a superconducting coil using a REBCO tape, a large screening current is induced by the magnetic field perpendicular to the tape. The irregular magnetic field generated by this screening current affects the magnetic-field distribution in high-field magnet applications, which require a magnetic field with high accuracy and temporal stability. Therefore, in these applications of the REBCO coil, we have to investigate and suppress the influence of the screening current in the REBCO tapes. In this study, we carried out experiments and numerical simulations focusing on the irregular magnetic field generated by the screening currents in multiple-REBCO-coil models assuming real operations in magnetic applications such as NMR/MRI system. The results of the numerical simulation are in good agreement with the behaviors of the screening field observed in the experimental results. In addition, we discussed the differences in the screening field for various excitation conditions using the numerical results of the current distribution in the coil.

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    20
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  • Reduction of irregular magnetic field generated by screening current in REBCO coil

    Hiroshi Ueda, Jun Saito, Yuta Ariya, Ayumu Mochida, Tao Wang, Xudong Wang, Koh Agatsuma, Atsushi Ishiyama

    IEEE Transactions on Applied Superconductivity   25 ( 3 ) 6603205  2015.06  [Refereed]

     View Summary

    In REBCO coils, the screening current flows in the tape in response to the normal component of the linkage flux to the tape's wide face. Generally, the radial component of the magnetic field is large at both ends of the coil winding. Therefore, changes in the winding arrangement may be expected to reduce screening current induction. Furthermore, multifilamentary or narrow REBCO tapes with widths of a few millimeters can be also expected to reduce the magnitude of the screening current. Based on the above considerations, in this paper, we numerically investigated the reduction effect on a magnetic field generated by a screening current in a REBCO coil, due to thinning tape width and varying coil winding arrangements. It was found that the screening field is inversely proportional to the number of tape filaments, whereas a smaller coil winding aspect ratio leads to a decrease in the screening field.

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    11
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  • Experimental results of 275-kV 3-kA REBCO HTS power cable

    Masashi Yagi, Jin Liu, Shinichi Mukoyama, Takaharu Mitsuhashi, Jun Teng, Naoki Hayakawa, Xudong Wang, Atsushi Ishiyama, Naoyuki Amemiya, Takayo Hasegawa, Takashi Saitoh, Osamu Maruyama, Takeshi Ohkuma

    IEEE Transactions on Applied Superconductivity   25 ( 3 ) 5401405 - 5  2015.06  [Refereed]

     View Summary

    A 30-m-long 275-kV 3-kA high-temperature superconducting (HTS) cable had been developed in a national project of the Materials and Power Applications of Coated Conductors project in Japan. The design of the cable was based on the design values obtained from ac loss properties, thermal behavior under short-circuit tests, and electrical properties, such as partial discharge properties, impulse withstand properties, and dielectric properties. Through the development, the material of the cable insulation was determined and designed on the basis of its design stresses and test conditions based on the IEC, JEC (Japan electrical standards), and other HTS demonstrations. This cable was also designed to withstand a short-circuit test of 63 kA for 0.6 s and to have low losses of 0.8 W/m at 3 kA, 275 kV, including ac loss and dielectric loss. Based on these designs, a 50-m cable was manufactured and tested. The short samples obtained from 50 m were confirmed to have the designed characteristics. Furukawa Electric constructed a demonstration system of a 30-m cable with two terminations and a cable joint. The demonstration had started since November 2012 at Shenyang in China. In this demonstration, a 30-day long-term test was conducted and monitored at a current of 3 kA and at a test voltage selected to verify a 30-year operational lifetime. Removal tests revealed the superior reliability of the 275-kV HTS cable system.

    DOI

  • Development of Evaluation Procedure for Critical Current of Periodically Bent Nb3Sn Strand

    KAJITANI Hideki, ISHIYAMA Atsushi, AGATSUMA Kou, MURAKAMI Haruyuki, HEMMI Tsutomu, KOIZUMI Norikiyo

    TEION KOGAKU (Journal of Cryogenics and Superconductivity Society of Japan)   50 ( 12 ) 608 - 615  2015  [Refereed]

     View Summary

    A<tt> </tt>cable-in-conduit (CIC) conductor using Nb3Sn strand is applied to an ITER TF coil. The Nb3Sn strand in the conductor is periodically bent due to electromagnetic force, which causes degradation of performance. This degradation should be evaluated to predict conductor critical current performance. In a past study, a numerical simulation model was developed to evaluate the superconductivity of a periodically bent single strand. However, this model is not suitable for application to strands in the conductor because of the extensive calculation time required. The author thus developed a new analytical model with a much shorter calculation time to evaluate the performance of periodically bent strand. This new model uses the classical model concept of a high transverse resistance model (HTRM). The calculated results show good agreement with the test results of a periodically bent Nb3Sn strand in a ends fixed beam model while there was little error in the uniformly bent model under high transverse load due to the difference in bending moment distribution between the two models. However, for both cases, the newly developed model has a much shorter calculation time than that required for numerical simulation. This indicates that a more practical solution can be achieved when evaluating the performance of periodically bent strands. Thus, the model developed in this study can be applied to evaluation of the performance of conductor incorporating many strands.

    DOI CiNii

  • SOBINMF for Automatic Removal of Ocular Artifacts from the EEG

    Tsubakida Hirohisa, Ono Yumie, Ishiyama Atsushi

    IEEJ Transactions on Electronics, Information and Systems   135 ( 8 ) 954 - 962  2015  [Refereed]

     View Summary

    This paper introduces a novel method to automatically remove electro-oculogram (EOG) from electroencephalogram (EEG) using second-order blind identification (SOBI) and nonnegative matrix factorization (NMF). To demonstrate the effectiveness of the proposed method, we applied SOBI, NMF, or combined SOBI and NMF (SOBINMF) to the EEG data during motor imagery task in which participants imagined moving their left or right hand. Ocular artifacts were removed more effectively in our proposed SOBINMF method compared to SOBI or NMF alone.

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    Scopus

  • Project Overview of HTS Magnet for Ultra-high-field MRI System

    Taizo Tosaka, Hiroshi Miyazaki, Sadanori Iwai, Yasumi Otani, Masahiko Takahashi, Kenji Tasaki, Shunji Nomura, Tsutomu Kurusu, Hiroshi Ueda, So Noguchi, Atsushi Ishiyama, Shinichi Urayama, Hidenao Fukuyama

    Proceedings of the 27th International Symposium on Superconductivity (ISS 2014)   65   217 - 220  2015  [Refereed]

     View Summary

    A project to develop an ultra-high-field magnetic resonance imaging (MRI) system based on HTS magnets using (RE)Ba2Cu3O7 (REBCO; RE=rear earth) coils is underway. The project is supported by the Japanese Ministry of Economy, Trade and Industry and aims to establish magnet technologies for a whole-body 9.4 T MRI system. REBCO wires have high critical current density in high magnetic fields and high strength against hoop stresses, and therefore, MRI magnets using REBCO coils are expected to have cryogenic systems that are smaller, lighter, and simpler than the conventional ones. A major problem in using REBCO coils for MRI magnets is the huge irregular magnetic field generated by the screening current in REBCO tapes. Thus, the main purpose of this project is to make the influence of this screening current predictable and controllable. Fundamental technologies, including treatment of the screening currents, were studied via experiments and numerical simulations using small coils. Two types of model magnets are planned to be manufactured, and the knowledge gained in the development of the model magnets will be reflected in the magnet design of a whole-body 9.4 T MRI system. (C) 2015 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

    DOI

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    18
    Citation
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  • Experiment and Numerical Simulation on Quench Detection in Cryocooler-Cooled YBCO Coil for SMES Application

    Yuta Masui, Xudong Wang, Atsushi Ishiyama, Tomonori Watanabe, Naoki Hirano, Shigeo Nagaya, Hiroshi Ueda

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   24 ( 3 ) 4601005  2014.06  [Refereed]

     View Summary

    In the real application of high-temperature superconducting (HTS) coils to a superconducting magnetic energy storage (SMES) system, coated conductors are cyclically subjected to tensile strain due to electrical charging and discharging. A quench is not only caused by failure in the power supply and cooling system but also could be induced by local deterioration of the superconducting characteristics because of the cyclic strain during operation. In such a local deterioration case, the conventional detection method using voltage signal for low-temperature superconducting (ITS) coils is not applicable for the HTS coils because of the significantly slow velocity of normal-zone propagation. Furthermore, the voltage detection method is considered to be extremely difficult because the noise of the converters and other equipment is much larger than the local normal-zone voltage of the HTS coils. Therefore, a new quench-detection method for HTS coils is required. In our previous studies, a current detection method was developed for a cryocooler-cooled SMES coil wound with a kA-class laminated bundle conductor composed of four electrically insulated coated conductors. In the present study, experiments and numerical simulations were carried out on a double pancake model coil that assumes real SMES operation to verify the validity of the current detection method.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Influence of Winding Accuracy on Magnetic Field Distribution in YBCO Pancake Coil for Cyclotron Application

    Tao Wang, Hiraku Karino, Kenta Michitsuji, Xudong Wang, Atsushi Ishiyama, Hiroshi Ueda, Mitsuhiro Fukuda, Tomonori Watanabe, Shigeo Nagaya

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   24 ( 3 ) 9002005  2014.06  [Refereed]

     View Summary

    In recent years, YBCO high-temperature superconducting (HTS) tapes have been expected to be applied to devices in power systems or in other industrial applications, owing to their rapidly improving quality and productivity. Our objective is to develop an HTS cyclotron with a compact body, high efficiency of output power, and high performance in heavy particle radiotherapy. In such an application, extremely high precision is required in the range 0.01% to 0.1% of magnetic field, both spatially and temporally. An isochronous field along with an azimuthally varying field is generated by an air-core pancake coil system during construction. Therefore, developing a technology for extremely high coil-winding accuracy is very important. In this study, we constructed an experimental model of a YBCO pancake coil using a high-precision coil winding machine. Then, the winding error in the radial and axial directions was experimentally evaluated using a pair of laser displacement meters and a surface roughness tester. We also developed a numerical simulation model to analyze the influence of winding error on the magnetic field distribution. The relationship between the winding error and the magnetic field of the meter-class YBCO coil assuming a real system was also evaluated by numerical simulation.

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    4
    Citation
    (Scopus)
  • Measurement and Simulation of Magnetic Field Generated by Screening Currents in HTS Coil

    Hiroshi Ueda, Mitsuhiro Fukuda, Kichiji Hatanaka, Kenta Michitsuji, Hiraku Karino, Tao Wang, Xudong Wang, Atsushi Ishiyama, So Noguchi, Yoshinori Yanagisawa, Hideaki Maeda

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   24 ( 3 ) 4701505  2014.06  [Refereed]

     View Summary

    In coils wound with high-temperature superconducting (HTS) tapes, large screening currents are induced in the tape by the radial component of the magnetic field. Furthermore, when a transport current is supplied to the HTS tape under a magnetic field, the total current (which consists of the transport and screening currents) flows inhomogeneously. The magnetic field generated by the screening currents affects the magnetic field distribution in cyclotron applications. Investigating the effects of the screening currents on the reduction, hysteresis, and drift of the magnetic field in the HTS coil is therefore necessary. In our previous studies, we have developed a novel simulation code for a three-dimensional electromagnetic field with the aim of clarifying these effects. In the present study, we measured the reduction and hysteresis of the magnetic field generated by the screening currents for a small model of HTS pancake coil. Additionally, we numerically investigated the influence of the screening current in the Furs coil on the spatial and temporal behavior of the magnetic field using our developed simulation code, which considers the nonlinear voltage-current characteristics.

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    48
    Citation
    (Scopus)
  • Numerical Structural Analysis on a New Stress Control Structure for High-Strength REBCO Pancake Coil

    Xudong Wang, Atsushi Ishiyama, Takuya Tsujimura, Hiroshi Yamakawa, Hiroshi Ueda, Tomonori Watanabe, Shigeo Nagaya

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   24 ( 3 ) 4601605  2014.06  [Refereed]

     View Summary

    A series of feasibility studies were carried out on the applications of a high-temperature superconducting (HTS) coil system for a medical accelerator system for particle cancer therapy by our group. A new HTS cyclotron is designed to be more compact and have higher efficiency than the conventional medical accelerator. High strength against electromagnetic forces is required for the development of compact HTS coils during the use of an HTS cyclotron. A new stress control structure for a high-strength REBCO pancake coil was proposed in the previous study. No deterioration was observed in the double pancake coil after a charging test of 1.5 kA at 4.2 K in 8-T backup fields. The maximum hoop stress was determined to be greater than 1.7 GPa because of the Lorentz force. The developed coil structure was able to share the hoop stress with not only the coil winding but also the reinforcing structures. In this study, numerical structural analysis based on the finite element method was performed on the new coil structure to clarify the mechanism of the stress sharing between the coil winding and reinforcing structures. In addition, the stress sharing effect of the meter-class REBCO coil assuming an HTS cyclotron system was determined.

    DOI

  • Superconducting Magnetic Energy Storage System (SMES)

    WATANABE Tomonori, ISHIYAMA Atsushi

    IEEJ Transactions on Sensors and Micromachines   134 ( 8 ) 546 - 548  2014  [Refereed]  [Invited]

     View Summary

    This article has no abstract.

  • Numerical Electromagnetic Analysis for Applied Superconductivity III : Superconductivity and Electromagnetic Analysis

    UEDA Hiroshi, ISHIYAMA Atsushi

    TEION KOGAKU   48 ( 9 ) 472 - 484  2013.09  [Refereed]  [Invited]

     View Summary

    In this paper, we describe a numerical method for an electromagnetic phenomenon in type-II superconductors containing pins. Models of type-II superconductors containing pins use the eddy current problem of Maxwells equations together with nonlinear constitutive relationships between the electric field (E) and the current density (J). The E-J relationship must lead to basic phenomena of superconductors such as the zero-resistance, flux flow, flux creep, hysteresis and magnetization. As typical models of the E-J relationship in superconductors, the critical state model, the power law "n-value model" and the percolation model are presented. Additionally, as an example, we introduce a superconducting slab, a magnetic shielding type of superconducting fault current limiter and a screening field in a HTS pancake coil.

    DOI CiNii

  • Status of a 275 kV Class REBCO Superconducting Cable Development

    S. Mukoyama, M. Yagi, T. Mitsuhashi, T. Nomura, J. Ten, R. Nakayama, T. Ohkuma, O. Maruyama, Y. Aoki, T. Saitoh, N. Amemiya, A. Ishiyama, N. Hayakawa

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   23 ( 3 )  2013.06  [Refereed]

     View Summary

    The REBCO high-temperature superconducting cable, rated at 275 kV and 3 kA, was developed in the Materials and Power Applications of Coated Conductors project in 2008. The cable is expected to be put to practical use as a backbone power line in the future because the transmission capacity is about the same as the UHV overhead transmission line. Transmission loss is significantly reduced by using superconducting wires instead of Cu or Al conductors. Furukawa Electric plans a demonstration of the 275 kV high-temperature superconducting cable. The cable system consists of a 30-m cable, terminations, a cable joint, and a cooling system. The 30-m cable has already been manufactured and installed on a test site. In this demonstration, various electrical evaluations will be conducted, such as a long-term test under a current of 3 kA, and the test voltage will be determined assuming 30 years of insulation degradation.

    DOI

    Scopus

    11
    Citation
    (Scopus)
  • Experiments and Numerical Simulations on Local Degradation Characteristics of Coated Conductor Due to Overcurrent

    Xudong Wang, Tao Wang, Atsushi Ishiyama, Masashi Yagi, Osamu Maruyama, Takeshi Ohkuma

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   23 ( 3 )  2013.06  [Refereed]

     View Summary

    Coated conductors are subjected to short-circuit currents 10 to 30 times greater than the operating current in the use of superconducting power cables. The I-c and thickness of the stabilizer are considered to be nonuniformly distributed in the real manufacturing process. Thus, the coated conductor may be damaged locally by the hot spot due to the overcurrent. Therefore, it is important to clarify the local degradation characteristics of the coated conductor and determine its tolerance against the fault current in the actual operation. In a previous study, overcurrent experiments and numerical simulations on thermal stress-strain were carried out on a coated conductor with a nonuniformly distributed I-c. In this study, two samples with nonuniformly distributed copper plating thickness were tested. Numerical simulations based on the finite element method were performed to simulate the temperature and thermal stress-strain distribution caused by the overcurrent. The nonuniform thickness of the copper plating and the longitudinal length of the nonuniform area were considered as the simulation parameters.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Status of a 275 kV Class REBCO Superconducting Cable Development

    S. Mukoyama, M. Yagi, T. Mitsuhashi, T. Nomura, J. Ten, R. Nakayama, T. Ohkuma, O. Maruyama, Y. Aoki, T. Saitoh, N. Amemiya, A. Ishiyama, N. Hayakawa

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   23 ( 3 )  2013.06  [Refereed]

     View Summary

    The REBCO high-temperature superconducting cable, rated at 275 kV and 3 kA, was developed in the Materials and Power Applications of Coated Conductors project in 2008. The cable is expected to be put to practical use as a backbone power line in the future because the transmission capacity is about the same as the UHV overhead transmission line. Transmission loss is significantly reduced by using superconducting wires instead of Cu or Al conductors. Furukawa Electric plans a demonstration of the 275 kV high-temperature superconducting cable. The cable system consists of a 30-m cable, terminations, a cable joint, and a cooling system. The 30-m cable has already been manufactured and installed on a test site. In this demonstration, various electrical evaluations will be conducted, such as a long-term test under a current of 3 kA, and the test voltage will be determined assuming 30 years of insulation degradation.

    DOI

    Scopus

    11
    Citation
    (Scopus)
  • Quench Detection Method for Cryocooler-Cooled YBCO Pancake Coil for SMES

    Hideaki Ohnishi, Atsushi Ishiyama, Tomonori Watanabe, Naoki Hirano, Shigeo Nagaya

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   23 ( 3 )  2013.06  [Refereed]

     View Summary

    In this study, we focus on a quench detection method for a cryocooler-cooled double pancake coil wound with an YBCO bundle conductor for superconducting magnetic energy storage. Because the local normal-zone propagation velocity is significantly slower in a high-temperature superconducting coil than that in a low-temperature superconducting coil, it is difficult to detect the local normal transition using a voltage between both coil ends. In the application of an YBCO coil for superconducting magnetic energy storage, quench detection is considered to be more difficult because of the noise of the converter or other equipment. Therefore, the normal transition and quench must be detected using some other method. A current detection method, which measures the current redistribution in the YBCO coil with hall probes, was proposed and verified to be able to determine the normal transition by the numerical simulations in the previous paper. In this study, on the basis of the current detection method, the experiments and numerical simulation were performed on a cryocooler-cooled small model double-pancake coil wound with an YBCO bundle conductor composed of four electrically insulated YBCO tapes. As the results, the current detection method was verified to be effective in detecting the local normal transition; Hall probes were used to measure the magnetic field and to estimate the current in individual YBCO tapes making up the bundle conductor.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Development of High Strength Pancake Coil With Stress Controlling Structure by REBCO Coated Conductor

    Shigeo Nagaya, Tomonori Watanabe, Tsutomu Tamada, Mitsuhito Naruse, Naoji Kashima, Toshio Katagiri, Naoki Hirano, Satoshi Awaji, Hidetoshi Oguro, Atsushi Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   23 ( 3 )  2013.06  [Refereed]

     View Summary

    High strength against electromagnetic force is required for high magnetic field and large capacity coil in order to develop large-capacity superconducting magnetic energy storage (SMES) systems for electric power system control. Also, suppression of delaminating of Yttrium (Y) based coated conductor in a coil is required to manufacture the highly reliable and durable superconducting coil. Insulating coating, using liquid resin of low-temperature-curable-polyamide, was developed and showed durability at very low temperature without deterioration of transport properties of superconducting wire in a coil. Combining paraffin molding, delaminating, and deterioration of transport properties of superconducting wire were not also observed in a coil. These insulating techniques were applied to the pancake coil, in which superconducting wire and the reinforcing outer plates of the coil withstand electromagnetic force. The double pancake coil of this coil structure, called "Yoroi-coil; Y-based oxide superconductor and reinforcing outer integrated coil" was prepared and the durability against electromagnetic force by hoop stress test was verified. The coil achieved 1.5 kA transporting at 4.2 K in 8 T backup magnetic field without the degradation of transport properties. Maximum hoop stress at the hoop stress test reached 1.7 GPa, based on the calculations. This result confirmed that Yoroi-coil structure has a capability to withstand the large hoop stress, which exceeded the tensile strength of Y-based coated conductors, and bring out highly durable and reliable superconducting coils.

    DOI

    Scopus

    34
    Citation
    (Scopus)
  • Development of 66 kV and 275 kV Class REBCO HTS Power Cables

    O. Maruyama, T. Ohkuma, T. Masuda, Y. Ashibe, S. Mukoyama, M. Yagi, T. Saitoh, T. Hasegawa, N. Amemiya, A. Ishiyama, N. Hayakawa

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   23 ( 3 )  2013.06  [Refereed]

     View Summary

    A Japanese national project called "Materials & Power Applications of Coated Conductors (M-PACC)" started in FY2008. In this project, we are developing a 66 kV/5 kA large-current high-temperature superconducting (HTS) cable and 275 kV/3 kA high-voltage HTS cable, using rare-earth barium copper oxide (REBCO) tapes. These HTS cables are expected to offer a compact cable with a large capacity and low power transmission loss. After the cable design has been studied and elemental technologies for each component of the cable system, such as ac loss reduction, protection against over-current, and high-voltage electrical insulation have been developed, two cable systems will be constructed and verified to meet the required specifications in FY2012. This paper describes the progress and status of these HTS cable developments in the M-PACC project.

    DOI

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    35
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  • Spatial and Temporal Behavior of Magnetic Field Distribution Due to Shielding Current in HTS Coil for Cyclotron Application

    Hiroshi Ueda, Mitsuhiro Fukuda, Kichiji Hatanaka, Tao Wang, Atsushi Ishiyama, So Noguchi

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   23 ( 3 )  2013.06  [Refereed]

     View Summary

    We intend to develop and obtain a compact, high-efficiency and high-performance cyclotron using the high-temperature superconducting (HTS) magnet technology. In cyclotron applications, a high-accuracy magnetic field distribution with an isochronous field and an azimuthally varying field is spatially and temporally required for an HTS coil. In coils wound with HTS tapes, large shielding currents are induced in the HTS tape by the radial component of the magnetic field. The magnetic field generated by the shielding current affects the magnetic field distribution in the cyclotron application in the following issues: (1) field reduction by the shielding current, (2) accuracy of the field distribution, (3) temporal stability of the time-dependent shielding currents, and (4) field repeatability after charge and discharge repetitions. These effects are very critical in cyclotron applications. We developed a novel numerical simulation based on the finite element method, boundary integral equation, and fast multipole method. We investigated the spatial and temporal behavior of the magnetic field attributed to the shielding current in the HTS coil for the HTS cyclotron application.

    DOI

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    26
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  • Conceptual Design of Next Generation HTS Cyclotron

    Hiroshi Ueda, Mitsuhiro Fukuda, Kichiji Hatanaka, Tao Wang, Xudong Wang, Atsushi Ishiyama, So Noguchi, Shigeo Nagaya, Naoji Kashima, Nobuyuki Miyahara

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   23 ( 3 )  2013.06  [Refereed]

     View Summary

    In recent years, the quality of high-temperature superconducting (HTS) tapes has been improving rapidly, becoming available in sufficient quantity and length, and can be applied to devices for power systems and industrial applications. Therefore, we are carrying out a feasibility study on the application of HTS coil to a medical accelerator system for particle cancer therapy, and designing a new HTS cyclotron that is to be compact, highly efficient, is able to extract high-energy beam and consume less power. In this paper, we report our effort to develop a conceptual magnetic design of a "next generation HTS cyclotron" using high-temperature superconducting technology.

    DOI

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    52
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  • 高温超電導コイルの安定性評価基準とクエンチ検出・保護 -SMES 用伝導冷却YBCO コイルを例として-

    石山 敦士, 植田 浩史, 王 旭東, 長屋 重夫, 渡部 智則

    低温工学   48 ( 4 ) 141 - 150  2013.04  [Refereed]  [Invited]

    DOI

  • 応用電磁気学:超電導機器応用のための電磁界数値解析II -有限要素法と境界要素法-

    植田 浩史, 石山 敦士

    低温工学   48 ( 2 ) 83 - 94  2013.02  [Refereed]  [Invited]

    DOI

  • Pursuing the flow of information: connectivity between bilateral premotor cortices predicts better accuracy in the phonological working memory task.

    Yumie Ono, Tatsuya Nanjo, Atsushi Ishiyama

    Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference   2013   7404 - 7  2013  [International journal]

     View Summary

    Using Magnetoencephalography (MEG) we studied functional connectivity of cortical areas during phonological working memory task. Six subjects participated in the experiment and their neuronal activity was measured by a 306-channel MEG system. We used a modified version of the visual Sternberg paradigm, which required subjects to memorize 8 alphabet letters in 2s for a late recall period. We estimated functional connectivity of oscillatory regional brain activities during the encoding session for each trial of each subject using beamformer source reconstruction and Granger causality analysis. Regional brain activities were mostly found in the bilateral premotor cortex (Brodmann area (BA) 6: PMC), the right dorsolateral prefrontal cortex (BA 9: DLPFC), and the right frontal eye field (BA 8). Considering that the left and right PMCs participate in the functions of phonological loop (PL) and the visuospatial sketchpad (VS) in the Baddeley's model of working memory, respectively, our result suggests that subjects utilized either single function or both functions of working memory circuitry to execute the task. Interestingly, the accuracy of the task was significantly higher in the trials where the alpha band oscillatory activities in the bilateral PMCs established functional connectivity compared to those where the PMC was not working in conjunction with its counterpart. Similar relationship was found in the theta band oscillatory activities between the right PMC and the right DLPFC, however in this case the establishment of functional connectivity significantly decreased the accuracy of the task. These results suggest that sharing the memory load with both PL- and VS- type memory storage circuitries contributed to better performance in the highly-demanding cognitive task.

    DOI PubMed

    Scopus

    1
    Citation
    (Scopus)
  • Pursuing the flow of information: Connectivity between bilateral premotor cortices predicts better accuracy in the phonological working memory task.

    Yumie Ono, Tatsuya Nanjo, Atsushi Ishiyama

    35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society(EMBC)     7404 - 7407  2013

    DOI

    Scopus

    1
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    (Scopus)
  • Design and evaluation of 275 kV-3 kA HTS power cable

    M. Yagi, S. Mukoyama, T. Mitsuhashi, T. Jun, J. Liu, R. Nakayama, N. Hayakawa, X. Wang, A. Ishiyama, N. Amemiya, T. Hasegawa, T. Saitoh, T. Ohkuma, O. Maruyama

    Physics Procedia   45   277 - 280  2013  [Refereed]

     View Summary

    A 275 kV 3 kA high temperature superconducting (HTS) cable has been developed in the Materials & Power Applications of Coated Conductors (M-PACC) project. The cable is expected to be put to practical use as the backbone power line in the future because the capacity of 1.5 GW is about the same as overhead transmission lines. The 30 m cable has been designed on the basis of design values that had been obtained by various voltage tests, AC loss measurement tests, short circuit tests, and other elementary tests. Cable insulation was determined by the design stresses and test conditions based on IEC, JEC (Japan electrical standards), and other HTS demonstrations. This cable was also designed to withstand the short circuit test of 63 kA for 0.6 seconds and to have low losses, including AC loss and dielectric loss of 0.8 W/m at 3kA, 275 kV. Based on the design, a 30 m cable was manufactured, and short samples during this manufacturing process were confirmed to have the designed characteristics. Furukawa Electric prepared a demonstration of the 30 m cable with two terminations and a cable joint. The long-term test under a current of 3 kA, and test voltage determined from 30 years of insulation degradation has been conducted since November 2012 at Shenyang in China. © 2013 The Authors.

    DOI

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    20
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  • Critical Current Degradation in High-Temperature Superconducting Tapes Caused by Temperature Rise

    Yazaki, Shinjiro, Karasawa, Akira, Kotoyori, Takuya, Ishiyama, Atsushi, Miyahara, Nobuyuki

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   23 ( 3 )  2013  [Refereed]

    DOI

  • Evaluation of conduction cooling effect of cryocooler-cooled HTS coils for SMES application

    Takuya Kotoyori, Hideaki Ohnishi, Yuta Masui, Atsushi Ishiyama, Watanabe Tomonori, Naoki Hirano, Shigeo Nagaya, K. Shikimachi

    IEEE Transactions on Applied Superconductivity   23 ( 3 )  2013  [Refereed]

     View Summary

    In recent years, the quality of high-temperature superconductors (HTS) has been improving. Our goal is to apply an HTS coil to superconducting magnetic energy storage, because an HTS coil is more thermally stable than a low-temperature superconductor coil owing to high thermal margin during its transition to the normal state and its high thermal capacity at a high operational temperature. On the other hand, to enhance the reliability and safety of an HTS coil, it is necessary to establish a stability criterion to prevent thermal and mechanical damages during a quench. Therefore, we have to clarify the thermal behavior of a cryocooler-cooled HTS coil assuming practical applications. In this study, we evaluated the cooling effect using a numerical simulation and thermal conduction experiments. The numerical simulation was based on the finite element analysis, and the thermal conduction experiments were carried out on a model coil wound with electrically insulated copper and stainless steel laminated tapes. These had the same shape and dimensions as YBCO tape, assuming an application to an superconducting magnetic energy storage coil. We focused especially on the cooling effect of a winding with paraffin impregnation compared with that of a dry winding. © 2002-2011 IEEE.

    DOI

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    7
    Citation
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  • Visual and Auditory Stimuli Associated with Swallowing Activate Mirror Neurons: A Magnetoencephalography Study

    Takashi Ushioda, Yutaka Watanabe, Yusuke Sanjo, Gen-yuki Yamane, Shinichi Abe, Yusuke Tsuji, Atushi Ishiyama

    DYSPHAGIA   27 ( 4 ) 504 - 513  2012.12  [Refereed]

     View Summary

    In the present study, we evaluated activated areas of the cerebral cortex with regard to the mirror neuron system during swallowing. To identify the activated areas, we used magnetoencephalography. Subjects were ten consenting volunteers. Swallowing-related stimuli comprised an animated image of the left profile of a person swallowing water with laryngeal elevation as a visual swallowing trigger stimulus and a swallowing sound as an auditory swallowing trigger stimulus. As control stimuli, a still frame image of the left profile without an additional trigger was shown, and an artificial sound as a false auditory trigger was provided. Triggers were presented at 3,000 ms after the start of image presentation. The stimuli were combined and presented and the areas activated were identified for each stimulus. With animation and still-frame stimuli, the visual association area (Brodmann area (BA) 18) was activated at the start of image presentation, while with the swallowing sound and artificial sound stimuli, the auditory areas BA 41 and BA 42 were activated at the time of trigger presentation. However, with animation stimuli (animation stimulus, animation + swallowing sound stimuli, and animation + artificial sound stimuli), activation in BA 6 and BA 40, corresponding to mirror neurons, was observed between 620 and 720 ms before the trigger. Besides, there were also significant differences in latency time and peak intensity between animation stimulus and animation + swallowing sound stimuli. Our results suggest that mirror neurons are activated by swallowing-related visual and auditory stimuli.

    DOI

    Scopus

    16
    Citation
    (Scopus)
  • 応用電磁気学:超電導機器応用のための電磁界数値解析I -電磁界数値解析の基礎-

    植田 浩史, 石山 敦士

    低温工学   47 ( 11 ) 623 - 632  2012.11  [Refereed]  [Invited]

    DOI

  • Current Margin of 66 kV Class HTS Power Cable Against Fault Current

    Xudong Wang, Kentaro Kojima, Masaya Kanemitsu, Atsusi Ishiyama, Masayoshi Ohya, Kazuya Ohmatsu, Osamu Maruyama, Takeshi Ohkuma

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   22 ( 3 )  2012.06  [Refereed]

     View Summary

    In practical applications, high temperature superconducting (HTS) power cables can be subjected to short-circuit fault currents. Further, these cables are assumed to operate over a period of 30 years. Therefore, it is important to investigate the current margin and aging degradation against the fault current. In order to ensure the over-current characteristics of 66 kV classHTS power cables against the fault current, preliminary experiments were carried out on some HTS model cables. Concurrently, numerical simulations were performed to clarify the electromagnetic and thermal behaviors of the HTS model cables under fault conditions. Moreover, the validity of our computer simulation was confirmed by comparing the experimental results with the simulation results. In this study, the maximum fault current in one GdBCO coated conductor assembled in the HTS power cable was numerically simulated. AC over-current experiments were carried out on an HTS model cable by using the maximum fault current of the simulation result to evaluate the current margin against the fault current under conduction cooling and liquid nitrogen bath cooling condition.

  • Overcurrent Tests and Numerical Simulations on a 66-kV-Class RE123 High-Temperature Superconducting Model Cable

    Xudong Wang, Atsushi Ishiyama, Masayoshi Ohya, Osamu Maruyama, Takeshi Ohkuma

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   22 ( 3 )  2012.06  [Refereed]

     View Summary

    In Japan, the development of a 66-kV-class superconducting power cable was started in 2008 as a national project. A high-temperature superconducting (HTS) power cable typically consists of a copper former, HTS conductor layers, electrical insulation layers, HTS shield layers, and copper shield layers. A 66-kV-class superconducting power cable may be subjected to a fault current of 31.5 kA(rms) for 2 s. Therefore, in order to ensure the stability and feasibility of the cable, the thermal characteristics and current distributions of the cable need to be investigated under fault conditions. In this study, overcurrent experiments were performed on a 2-m-long HTS model cable. Numerical simulations were also performed on the model cable by using a computer program on the basis of a 3D finite element method and an electrical circuit model.

    DOI

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    4
    Citation
    (Scopus)
  • Current Margin of 66 kV Class HTS Power Cable Against Fault Current

    Xudong Wang, Kentaro Kojima, Masaya Kanemitsu, Atsusi Ishiyama, Masayoshi Ohya, Kazuya Ohmatsu, Osamu Maruyama, Takeshi Ohkuma

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   22 ( 3 )  2012.06  [Refereed]

     View Summary

    In practical applications, high temperature superconducting (HTS) power cables can be subjected to short-circuit fault currents. Further, these cables are assumed to operate over a period of 30 years. Therefore, it is important to investigate the current margin and aging degradation against the fault current. In order to ensure the over-current characteristics of 66 kV classHTS power cables against the fault current, preliminary experiments were carried out on some HTS model cables. Concurrently, numerical simulations were performed to clarify the electromagnetic and thermal behaviors of the HTS model cables under fault conditions. Moreover, the validity of our computer simulation was confirmed by comparing the experimental results with the simulation results. In this study, the maximum fault current in one GdBCO coated conductor assembled in the HTS power cable was numerically simulated. AC over-current experiments were carried out on an HTS model cable by using the maximum fault current of the simulation result to evaluate the current margin against the fault current under conduction cooling and liquid nitrogen bath cooling condition.

    DOI

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    6
    Citation
    (Scopus)
  • Quench Detection and Protection of Cryocooler-Cooled YBCO Pancake Coil for SMES

    Hiroshi Ueda, Atsushi Ishiyama, Kazuki Muromachi, Takahiro Suzuki, Koji Shikimachi, Naoki Hirano, Shigeo Nagaya

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   22 ( 3 )  2012.06  [Refereed]

     View Summary

    In this paper, we focus on the quench detection and protection of a cryocooler-cooled pancake coil for SMES wound with a YBCO bundle conductor composed of laminated electrically insulated YBCO-coated conductors. Because the normal-zone propagation velocity is much slower in a high-temperature superconducting (HTS) coil than in a low-temperature superconducting (LTS) coil, the detection of the non-recovering normal zone using a voltage signal is quite difficult. Quench detection is considered to be more difficult during SMES operation because of the noise of the converter or other equipment. Therefore, a quench must be detected using some other method. In the previous paper, we showed that a quench in the coil could be detected by observing the transposition of the current in the bundle conductor caused by local normal transition. In this paper, based on this quench detection method, we investigate the transposition of current and the thermal behavior during the quench detection and the dumping of the stored energy by an external resistance in coils wound with a YBCO laminated bundle conductor for SMES and determine the appropriate stabilizer thickness of the YBCO-coated conductors.

    DOI

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    10
    Citation
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  • Current Status of Superconducting Technology for Medical Application

    ISHIYAMA Atsushi

    IEEJ Transactions on Sensors and Micromachines   132 ( 5 ) 276 - 277  2012.05  [Invited]

     View Summary

    This article has no abstract.

    DOI CiNii

    Scopus

  • Numerical analyses of the electromagnetic force acting on high-temperature superconducting power cables due to fault current

    X. Wang, A. Ishiyama, M. Ohya, O. Maruyama, T. Ohkuma

    SUPERCONDUCTOR SCIENCE & TECHNOLOGY   25 ( 5 )  2012.05  [Refereed]

     View Summary

    In Japan, the development of the 66 kV class REB2C3O7-x (RE123; RE stands for rare earth) high-temperature superconducting (HTS) power cable was begun in 2008 as a national project. 66 kV class RE123 HTS power cables may be subjected to a fault current of 31.5 kA(rms) for 2 s. Therefore, the electromagnetic and thermal characteristics of HTS power cables have to be determined under fault conditions to ensure stability and feasibility. In this study, numerical analyses were performed using a computer program on the basis of the finite element method and an equivalent circuit model to evaluate the electromagnetic and thermal behaviors of a 66 kV class HTS model cable resulting from the fault current. The electromagnetic forces acting on coated conductors that are assembled in the HTS model cable were also numerically simulated under the fault condition. The result found was that the maximum electromagnetic force acting on the coated conductor in the peeling and compression direction was less than 20 kPa. However, the irreversible I-c degradations caused by the peeling and compression stress were above several MPa in previous studies. Thus, the results of this study indicate a low probability of I-c degradation of the 66 kV class HTS power cable being caused by the electromagnetic force due to the fault current.

    DOI

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    3
    Citation
    (Scopus)
  • Design and evaluation of 66 kV-class "3-in-One" HTS cable using REBCO wires

    M. Ohya, H. Hirota, T. Masuda, N. Amemiya, A. Ishiyama, T. Ohkuma

    SUPERCONDUCTIVITY CENTENNIAL CONFERENCE 2011   36   849 - 854  2012  [Refereed]

     View Summary

    Sumitomo Electric (SEI) has been involved in the development of 66 kV-class HTS cables using REBCO wires. One of the technical targets is to reduce the AC loss to less than 2 W/m/phase at 5 kA. SEI has developed a clad-type textured metal substrate with lower magnetization loss than NiW substrate. REBCO tapes 30 mm-wide were slit into 4 mm-wide strips, and these strips were wound spirally on a former with small gaps. The measured AC loss of the manufactured cable was 1.8 W/m/phase at 5 kA, achieving the AC loss goal. (C) 2012 Published by Elsevier B. V. Selection and/or peer-review under responsibility of the Guest Editors.

    DOI

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    6
    Citation
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  • Development of 66 kV class REBCO superconducting cable

    M. Ohya, T. Masuda, N. Amemiya, A. Ishiyama, T. Ohkuma

    ADVANCES IN SUPERCONDUCTIVITY XXIV   27   364 - 367  2012  [Refereed]

     View Summary

    Sumitomo Electric Industries (SEI) has been involved in the development of 66 kV/5 kA-class HTS cables using REBCO wires. One of the technical targets was to reduce the AC loss to less than 2 W/m/phase at 5 kA. SEI developed a clad-type textured metal substrate with lower magnetization loss than NiW substrates. REBCO wires of 30 mm wide were slit into 4 mm-wide strips, and these strips were wound spirally on a former with small gaps. The measured AC loss of the manufactured cable was 1.8 W/m/phase at 5 kA, achieving the AC loss goal. Another important target was to manage fault current. The copper protection layers were designed based on simulation findings. Fault current tests (max. 31.5 kA, 2 sec) showed that the designed HTS cable has the required withstanding performance. The development of the elemental technologies was finished on schedule, and a 15 m-long HTS cable system will be constructed to demonstrate that it meets all the required specifications. (C) 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of ISS Program Committee.

    DOI

  • Development of REBCO HTS power cables

    O. Maruyama, T. Ohkuma, T. Masuda, M. Ohya, S. Mukoyama, M. Yagi, T. Saitoh, N. Aoki, N. Amemiya, A. Ishiyama, N. Hayakawa

    SUPERCONDUCTIVITY CENTENNIAL CONFERENCE 2011   36   1153 - 1158  2012  [Refereed]

     View Summary

    A Japanese national project, called "Materials & Power applications of Coated Conductors (M-PACC)", started in FY2008. In this project, we are developing 66 kV/5 kA large current high temperature superconducting (HTS) cable and 275 kV/3 kA high voltage HTS cable using REBCO tapes. These HTS cables are expected as a compact size with large capacity and low loss power transmission. We have examined AC loss, thermal characteristics of the cables under over-current, the optimum cable design and so on. After the design studies and elemental tests are completed, long cable systems will be built for verification purposes. This paper described the overview and current status of these HTS cables development in the M-PACC project. (PACS: 84.71.Fk) (C) 2012 Published by Elsevier B.V. Selection and/or peer-review under responsibility of the Guest Editors.

    DOI

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    11
    Citation
    (Scopus)
  • Design and evaluation of 66 kV-class HTS power cable using REBCO wires

    M. Ohya, H. Yumura, T. Masuda, N. Amemiya, A. Ishiyama, T. Ohkuma

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   471 ( 21-22 ) 1279 - 1282  2011.11  [Refereed]

     View Summary

    Sumitomo Electric (SEI) has been involved in the development of 66 kV-class HTS cables using REBCO wires. One of the technical targets in this project is to reduce the AC loss to less than 2 W/m/phase at 5 kA. SEI has developed a clad-type of textured metal substrate with lower magnetization loss compared with a conventional NiW substrate. In addition, 30 mm-wide REBCO tapes were slit into 4 mm-wide strips, and these strips were wound spirally on a former with small gaps. The AC loss of a manufactured 4-layer cable conductor was 1.5 W/m at 5 kA at 64K. Given that the AC loss in a shield layer is supposed to be one-fourth of a whole cable core loss, our cables are expected to achieve the AC loss target of less than 2 W/m/phase at 5 kA. Another important target is to manage a fault current. A cable core was designed and fabricated based on the simulation findings, and over-current tests (max. 31.5 kA, 2 s) were conducted to check its performance. The critical current value of the cable cores were measured before and after the over-current tests and verified its soundness. A 5 kA-class current lead for the cable terminations was also developed. The current loading tests were conducted for the developed current leads. The temperature distribution of the current leads reached to the steady-state within less than 12 h, and it was confirmed that the developed current lead has enough capacity of 5 kA loading. (C) 2011 Elsevier B.V. All rights reserved.

    DOI

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    7
    Citation
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  • Progress of 275 kV-3 kA YBCO HTS cable

    M. Yagi, S. Mukoyama, N. Amemiya, A. Ishiyama, X. Wang, Y. Aoki, T. Saito, T. Ohkuma, O. Maruyama

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   471 ( 21-22 ) 1274 - 1278  2011.11  [Refereed]

     View Summary

    A 275 kV-3 kA high temperature superconducting (HIS) cable has been developed in the Materials & Power Applications of Coated Conductors (M-PACC) project.
    AC loss reduction of a two-layer HTS conductor was undertaken by removing the edges of YBCO tapes with low critical current density. The HTS conductor using these tapes was fabricated, and low loss of 0.235 W/m at 3 kA(rms) was achieved.
    The 275 kV-3 kA cable was designed, and the 2 m model cables were fabricated. This cable had 325 mm(2) copper stranded former inside the HTS conductor and a 310 mm(2) copper shield layer on the HTS shield layer for over-current protection. These cables withstood an over-current of 63.0 kA for 0.6 s, which is the worst situation for 275 kV systems.
    The partial discharge (PD) and V-t characteristics of a liquid nitrogen (LN(2))/polypropylene (PP) laminated paper composite insulation system have been integrated into the design of the insulation for the 275 kV cable. The results revealed that the PD inception stress (PDIE) did not depend on the insulation thickness, and that lifetime indices of V-t characteristics at PD inception were as high as about 80-100. (C) 2011 Elsevier B.V. All rights reserved.

    DOI

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    32
    Citation
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  • Quench Behavior and Protection in Cryocooler-Cooled YBCO Pancake Coil for SMES

    Atsushi Ishiyama, Hiroshi Ueda, Yoshiaki Aoki, Koji Shikimachi, Naoki Hirano, Shigeo Nagaya

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   21 ( 3 ) 2398 - 2401  2011.06  [Refereed]

     View Summary

    The thermal behavior of a high-temperature superconducting (HTS) coil is significantly different from that of low-temperature superconducting (LTS) coil because it has a greater volumetric heat capacity at the temperature required for practical use. Therefore, the possibility of quench in HTS coils is much lower than that in LTS coils. In the application of the YBCO coil to Superconducting Magnetic Energy Storage (SMES) system, electrical charging and discharging are repeated; therefore, the superconducting characteristics of the YBCO coated conductor may deteriorate as a result of cyclic subjection to tensile strain. To enhance the reliability and safety of HTS coil, protection scheme assuming a quench is also required for HTS coil. In this study, we focus on the coil wound with YBCO laminated bundle (parallel) conductor supposing SMES application and investigate the characteristics of normal-zone propagation and the thermal behavior within the coil during a quench by using a newly developed computer code based on the finite element method and an equivalent circuit. And we also propose a quench detection method using observation of nonuniform current in YBCO laminated bundle conductor and discuss the validity of the detection method comparing with conventional quench-voltage detection.

    DOI

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    26
    Citation
    (Scopus)
  • Over-Current Characteristics of 66-kV RE123 HTS Power Cable

    Xudong Wang, Atsushi Ishiyama, Masayoshi Ohya, Noboru Fujiwara

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   21 ( 3 ) 1013 - 1016  2011.06  [Refereed]

     View Summary

    In Japan, the development of the 66-kV-class superconducting power cable was begun in 2008 as a national project. A high-temperature superconducting (HTS) power cable typically consists of a copper former, HTS conductor layers, electrical insulation layers, HTS shield layers, and copper shield layers. 66-kVclass superconducting power cables may be subjected to a fault current of 31.5 kA(rms) for 2 s. Therefore, in order to ensure the stability and feasibility of superconducting power cables, we need to investigate these cables with respect to their thermal characteristics and current distribution under fault conditions. In this study, we carried out over-current experiments on a 2-m-long HTS model cable. We also performed numerical simulations on the model cable by using a computer program developed by us on the basis of a 3D finite element method (FEM) and an electrical circuit model.

    DOI

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    16
    Citation
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  • Over-Current Characteristics of 275-kV Class YBCO Power Cable

    Atsushi Ishiyama, Xudong Wang, Hiroshi Ueda, Toshikuni Uryu, Masashi Yagi, Noboru Fujiwara

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   21 ( 3 ) 1017 - 1020  2011.06  [Refereed]

     View Summary

    In Japan, a project for the development of a 275-kV class YBCO power cable started in 2008. High-temperature superconducting (HTS) power cables typically consist of a copper former, an HTS conductor layer, an electrical insulation layer, an HTS shield layer, and a copper shield layer. In practical applications, the 275-kV class transmission line may be subjected to short-circuit fault currents such as 63 kA(rms) for a duration of 0.6 s. Therefore, in order to ensure the stability and demonstrate the feasibility of the cable, it is important to estimate the current distribution and temperature increase under the fault condition. We designed the copper former, copper shield layer, and copper plating of the YBCO coated conductor carefully so as to fulfill the requirements of practical applications. In this study, we carried out over-current experiments on a 2-m long YBCO model cable and performed numerical simulations by a computer program developed using the finite element method (FEM) and an electric circuit model. We investigated the electromagnetic and thermal behaviors of the cable under fault conditions from the experimental and simulation results.

    DOI

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    11
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  • Current Margin Against the Fault Current in REBCO Coated Conductors

    Atsusi Ishiyama, Hiroshi Momotari, Xudong Wang, Michio Arai, Hiroshi Ueda, Masayoshi Ohya, Kazuya Ohmatsu, Noboru Fujiwara

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   21 ( 3 ) 3033 - 3036  2011.06  [Refereed]

     View Summary

    The application of yttrium barium copper oxide (YBCO) coated conductors in power cables is anticipated. In practical applications, high-temperature superconducting (HTS) cables can be subjected to short-circuit fault current and are expected to operate for over 30 years. In order to safeguard the current margin of YBCO coated conductors against fault current, we carried out preliminary experiments on overcurrent characteristics using an HTS model cable. Meanwhile, we performed numerical simulations to clarify the electromagnetic and thermal behaviors of the HTS model cable. In this study, we numerically simulated the fault current waveform in each YBCO coated conductor that constitutes an entire cable. We then carried out experiments focusing on the current-voltage (I - V) characteristics and the current margin without causing critical current (I(c)) degradation against the fault current by varying the amplitude of the waveform obtained numerically. Furthermore, we repeatedly applied the fault current to a YBCO coated conductor to experimentally investigate the I(c) degradation caused by iterative fault current.

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  • Degradation of YBCO Coated Conductors Due to an Over-Current Pulse

    Atsushi Ishiyama, Michio Arai, Hiroshi Momotari, Xudong Wang, Hiroshi Ueda, Takashi Saito, Yuji Aoki, Masashi Yagi, Takato Machi, Noboru Fujiwara

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   21 ( 3 ) 3025 - 3028  2011.06  [Refereed]

     View Summary

    YBCO coated conductors are candidate materials for future electric power devices such as transmission cables, transformers, and fault current limiters. In practical applications, YBCO coated conductors are subject to short-circuit fault currents greater than the operating current. These fault currents cause heat generation, resulting in degradation of the characteristics of YBCO coated conductors. It is therefore necessary to identify the maximum temperatures under which YBCO coated conductors can operate without suffering degradation. To date, we have carried out preliminary experiments on the degradation of YBCO coated conductors due to an over-current pulse. We also focused on the relationship between increases in temperature and Ic degradation. In this study, we prepared YBCO coated conductors fabricated by TFA-MOD method. We also carried out over-current tests to investigate the Ic degradation and performed numerical simulations on thermal stress to estimate the stress and strain acting on the YBCO layer.

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    8
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  • Numerical Simulation of Current Distribution in Cable-in-Conduit Conductor for ITER TF Coil

    Hideki Kajitani, Atsushi Ishiyama, Norikiyo Koizumi, Haruyuki Murakami, Hideo Nakajima

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   21 ( 3 ) 1964 - 1968  2011.06  [Refereed]

     View Summary

    The critical current of a cable-in-conduit conductor (CICC) for an ITER TF coil was measured using the SULTAN test facility. It was found that a non-uniform current distribution was established due to a non-uniform joint resistance. To evaluate the critical current performance accurately, we used a solder-filled joint. To study the effect of this solder-filled joint on the current distribution, we used a lumped circuit model and a distributed circuit model for the conductor and the joint, respectively, and combined the two to develop a new analysis model. This enabled us to solve the distributed circuit equation using only a few iterations, resulting in considerable reduction of the calculation time. Simulation results showed that, although the current distribution was non-uniform due to the ramping current, it improved at the current sharing temperature. This indicated that the solder-filled joint effectively improved the current distribution.

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    4
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  • Effect of Neutron Irradiation on High-Temperature Superconductors

    Toru Aoki, Hiroshi Ueda, Atsushi Ishiyama, Nobuyuki Miyahara, Naoji Kashima, Shigeo Nagaya

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   21 ( 3 ) 3200 - 3202  2011.06  [Refereed]

     View Summary

    In recent years, rapid improvements have been made to the quality of high-temperature superconductors (HTSs). We carried out a feasibility study on the application of HTS coils in medical accelerators, which are used for particle cancer therapy. In this application, HTSs are exposed to radiation. As a result, the HTS conductors become radioactive, thereby making the operation and maintenance of the reactors or accelerators difficult. Further, radiation affects the superconducting characteristics and causes an increase in the amount of nuclear waste generated. Therefore, it is necessary to investigate the effect of radiation on HTSs. In this study, we carried out irradiation experiments on Bi-2223 and YBCO tapes at room temperature by using 14-MeV neutrons (dose: 77 kGy). We also performed radioactive analyses on HTS tapes and carried out current-voltage (I - V) measurements on the tapes immersed in a liquid-nitrogen (LN(2)) bath, before and after irradiation. The irradiation to YBCO had been conducted in the past[1]. We irradiated neutrons to YBCO and Bi-2223 tapes on the assumption that they will be applied by the medical accelerator.

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    17
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  • Evaluation of Positional Stability in Active Magnetic Levitation Using Spherical HTS Bulk for Inertial Nuclear Fusion

    Tao Wang, Hiroshi Ueda, Koh Agatsuma, Atsushi Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   21 ( 3 ) 1579 - 1583  2011.06  [Refereed]

     View Summary

    Fuel supply is a fundamental issue in application of inertial nuclear fusion. To address this issue, we propose the use of an HTS superconductor capsule containing nuclear fuel, which can levitate in a magnetic field. During magnetic levitation, positional stability is important because it affects levitation accuracy to the focal point of giant lasers. We have developed a numerical simulation program based on a 3-D hybrid finite element and boundary element method to evaluate positional stability during magnetic levitation. Moreover, we have optimally designed and constructed a multi-coil system wherein spherical HTS bulk of 5 mm diameter can levitate stably. Finally, we have conducted the experiments for the evaluation of magnetic levitation, and compared the results with our simulation.

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  • Model Cable Tests for a 275 kV 3 kA HTS Power Cable

    Shinichi Mukoyama, Masashi Yagi, Tokui Yonemura, Tomoya Nomura, Noboru Fujiwara, Y. Ichikawa, Yuji Aoki, Takashi Saitoh, Naoyuki Amemiya, Atsushi Ishiyama, Naoki Hayakawa

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   21 ( 3 ) 976 - 979  2011.06  [Refereed]

     View Summary

    High-temperature superconducting (HTS) cables are considered the next generation transmission line because they are compact, lightweight, and demonstrate large capacity and low loss compared to conventional cables. In particular, since a coated conductor (YBCO wire) provides high critical current, high magnetic-field property, low AC loss, and low cost, it is expected to make the HTS cable more attractive than other superconducting wire. In Japan, 66/77 kV HTS cables have developed for about 20 years. We started developing 275 kV class HTS cables three years ago based on 66/77 kV HTS cables. The goal is a 275 kV 3 kA cable with a capacity of 1.5 GVA, the same capacity as a typical overhead transmission line, which serves as the backbone of Japanese power networks.
    The following technical developments will be carried out: high current and low AC loss cable conductors and high voltage insulation and low dielectric loss cables. Regarding high current and low AC loss cable conductors, 3-kA cables have been fabricated, and AC losses have been measured. We found that using thin YBCO wire reduced AC losses in experiments.

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  • Application of superconductivity technology to heavy-ion accelerator for cancer therapy

    ISHIYAMA Atsushi, NODA Koji

      80 ( 1 ) 24 - 29  2011.01  [Refereed]  [Invited]

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  • Differences in delta wave power between spontaneous and passive perception of ambiguous figures

    Tatsuya Nanjo, Atsushi Ishiyama, Naoko Kasai, Yumie Ono

    NEUROSCIENCE RESEARCH   71 ( S ) E173 - E173  2011

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  • The change of EEG regarding with settlement of memory

    Tetsu Jyo, Minoru Kawasaki, Hideki Nojo, Atushi Ishiyama, Naoko Kasai, Yumie Ono

    NEUROSCIENCE RESEARCH   71 ( S ) E278 - E278  2011

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  • Nostalgic music enhances asymmetry in EEG power

    Mari Hatano, Atsushi Ishiyama, Naoko Kasai, Yumie Ono

    NEUROSCIENCE RESEARCH   71 ( S ) E269 - E269  2011

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  • Degradation characteristics of YBCO coated conductors due to fault-current in power cable applications

    H. Kono, X. Wang, H. Ueda, A. Ishiyama, T. Saitoh, Y. Aoki, M. Yagi, S. Mukoyama, N. Fujiwara

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   470 ( 20 ) 1334 - 1337  2010.11  [Refereed]

     View Summary

    In high temperature superconductor applications used in electric power devices, YBCO coated conductors may be subjected to short-circuit fault-currents that are 10-30 times the normal operating current. These over-currents cause heat generation, resulting in 1, degradation of the YBCO coated conductor. Therefore, it is necessary to fully investigate the degradation characteristics of YBCO coated conductors. We previously conducted preliminary experiments on the degradation of YBCO sample tapes resulting from the over-current pulse drive.
    In this study, we analyzed the waveform of fault-current that is supposed to flow into the YBCO coated conductor when a short-circuit fault occurs in a power cable application, by using a newly developed numerical simulation program. We also carried out experiments in which an over-current with the analyzed fault-current waveform was applied to two YBCO sample tapes. We then investigated the degradation characteristics, focusing on the amount of current permitted. Experimental results showed that both the sample tapes (initial I(c) = 118.6 A and 123.2 A) were degraded by applying an over-current with a peak value of 320 A. (C) 2010 Published by Elsevier B.V.

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  • Computer simulation of fault current characteristics in 275 kV class YBCO power cable

    S. Sato, X. Wang, H. Ueda, A. Ishiyama, M. Yagi, S. Mukoyama, T. Saitoh, Y. Aoki, N. Fujiwara

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   470 ( 20 ) 1572 - 1575  2010.11  [Refereed]

     View Summary

    In japan, the development of a 275 kV class YBCO power cable was started in 2008 with the support of the New Energy and Industrial Technology Development Organization (NEDO). In the designing of 275 kV YBCO power cable, the thickness of insulator is required to be 26 mm. Thus, in order to design the 275 kV YBCO power cable, it is important to estimate the thermal diffusion through the electrical insulation layer for designing the high-voltage YBCO power cable. Furthermore, YBCO power cables might be subjected to short-circuit fault currents that are 10-30 times a normal operating current. Therefore, in order to ensure stability and feasibility of superconducting power cables, we need to investigate the thermal characteristics and current distribution in the cable in the normal and fault conditions. The objective of this study is to investigate the thermal characteristics and dielectric performance in 275 kV class power cables. We carried out experiments on dummy cables in a steady state to clarify the distribution of temperature. In order to estimate the thermal conductivity and the heat capacity of the insulation layer, we performed numerical simulations using a developed computer program on the basis of the 3D finite element method. We also measured a tans and permittivity of an insulation layer in order to investigate the dielectrical performance. (C) 2010 Published by Elsevier B.V.

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  • Design and evaluation of 66 kV class RE-123 superconducting cable

    T. Minamino, M. Ohya, H. Yumura, T. Masuda, T. Nagaishi, Y. Shingai, X. Wang, H. Ueda, A. Ishiyama, N. Fujiwara

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   470 ( 20 ) 1576 - 1579  2010.11  [Refereed]

     View Summary

    In the new national project, as wire and cable development, Sumitomo Electric Industries, Ltd. (SEI) is trying to develop a 66 kV/5 kArms high temperature superconducting (HIS) cable with its own REBa(2)Ca(3)O(x) (RE-123, RE = rare earth element) coated conductors. In an actual power grid, an inflow of current higher than the normal rated power (fault-current) can occur. The maximum fault-current condition is set at 31.5 kArms for 2s for 66 kV-class transmission system in this project. Therefore, one of the technical targets in this project is to design the wires and cables to survive at this fault-current condition. As the first step, the prototype HIS cable was designed against the fault-current condition of 31.5 kArms for 2 s. The wires have copper plating as a stabilizer layer not to be damaged by over-currents. The designed HIS cable has a copper former and copper shield layers in parallel with the HIS conducting layers and HTS shield layers, respectively, to control the temperature rises in the cable core at fault-current conditions. As the second step, a sample HIS cable core was fabricated and fault-current tests were conducted to check its soundness. The temperature rises in the cable core were measured under various fault-current conditions. The critical current of the cable core was measured before and after the fault-current tests, and no deterioration in the critical current characteristics was observed. However, there was slight degradation of the n value. The investigation will be conducted, and the results will be fed back to designs of the RE-123 wires and cables. (C) 2010 Elsevier B.V. All rights reserved.

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  • Numerical simulation on fault current condition in 66 kV class RE-123 superconducting cable

    X. Wang, H. Ueda, A. Ishiyama, M. Ohya, H. Yumura, N. Fujiwara

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   470 ( 20 ) 1580 - 1583  2010.11  [Refereed]

     View Summary

    The new Japanese national project of development of 66 kV/5 kA high-temperature superconducting (HIS) power cables has been started since 2008. In an AC power system, a fault current may flow in the event of a short circuit accident. The maximum fault current condition is defined to be 31.5 kA(rms) for duration of 2 s for 66 kV class transmission line in this project. Therefore, one of the technical targets in this project is to design the HIS power cable to survive at this fault current condition. The coated conductors have copper layer as a stabilizer not to be damaged by over-currents. The HIS cable has a copper former and copper shield layers in parallel with the HIS conductor layers and HIS shield layers, respectively, to control the temperature rises in the HIS cable at a fault accident. In this study, we simulated the maximum temperature rises in the HIS power cable at the fault current condition of 31.5 kA(rms) for 25 in order to design the copper stabilizer and copper shield layers by using a computer program we developed on the basis of 3D finite element method (FEM) and electrical circuit model. (C) 2010 Published by Elsevier B.V.

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  • Determination of stabilizer thickness for YBCO coated conductors based on coil protection

    Y. Kawai, A. Ishiyama, H. Ueda, S. Nagaya, K. Shikimachi, N. Hirano

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   470 ( 20 ) 1865 - 1869  2010.11  [Refereed]

     View Summary

    The possibility of the occurrence of quench caused by mechanical disturbance in high-temperature superconductors (HTS&apos;s) is much lower than that in low-temperature superconductors. However, to enhance the reliability and safety of HTS coils, it is necessary to establish a stability criterion and a protection scheme on the basis of the assumption that the quench is caused by the failure in power supply, cooling systems, etc. In this study, we assume that the stored magnetic energy in the HTS coil is dissipated by an external resistance that acts as a quench protection. Under this assumption, we derive a function that examines the heat balance of quenching YBCO coil under an adiabatic condition and propose a criterion using the derived function to determine an appropriate stabilizer thickness of YBCO conductors. (C) 2010 Published by Elsevier B.V.

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  • Improvement of a High-Gradient Magnetic Separation System for Trapping Immunoglobulin in Serum

    Hiroshi Ueda, Koh Agatsuma, Shuichiro Fuchino, Tomohiro Imura, Mitsuho Furuse, Kazuhiro Kajikawa, Atsushi Ishiyama, Tatsuo Koizumi, Shinichiro Miyake

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   20 ( 3 ) 949 - 952  2010.06  [Refereed]

     View Summary

    Recently, affinity magnetic beads have been widely used in immunomagnetic cell sorting (IMCS) technology. Today, we can easily sort and analyse DNA and antibodies (immunoglobulin) using various types of affinity magnetic beads available in the market. The diameters of the affinity magnetic beads used in immunomagnetic cell sorting are above approximately 1 mu m because of the low magnetic fields induced by permanent magnets. At present, nanosized affinity magnetic beads are strongly desired to achieve high resolutions. We have been studying and attempting to develop a high-gradient magnetic separation (HGMS) system that employs a superconducting magnet to induce a considerably higher magnetic field than that induced by a permanent magnet. The objective is to trap smaller nanosized affinity magnetic beads using a filter made of fine stainless steel wool. In a previous study, we constructed a prototype of a desktop-type HGMS system using a cryocooler-cooled LTS magnet; we conducted preliminary experiments on trapping nanosized magnetic particles and investigated the magnetic field distribution and magnetic force around a magnetic wire in the filter by means of a numerical simulation.
    In this study, we succeeded in producing prototype nanobeads covered with the biosurfactant of a high-affinity ligand system for immunoglobulin G and M. Furthermore, we attempted to improve the recovery of nanobeads by adding a resonance circuit to the HGMS system. In practice, the trapped nanobeads attract one another and agglomerate due to their remaining magnetization when the magnetic field is decreased to 0 T. Therefore, the nanobeads and wire are demagnetized in the AC magnetic field by the resonance circuit, making good use of the superconducting magnet of the HGMS system.

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  • Thermal Characteristics of 275 kV/3 kA Class YBCO Power Cable

    Xudong Wang, Hiroshi Ueda, Atsushi Ishiyama, Masashi Yagi, Takashi Saitoh, Yuji Aoki, Noboru Fujiwara

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   20 ( 3 ) 1264 - 1267  2010.06  [Refereed]

     View Summary

    In Japan, the development of a 275 kV/3 kA class YBa(2)Cu(3)O(7) (YBCO) power cable was started in 2008. A high-temperature superconducting (HTS) power cable typically consists of a copper former, HTS conductor layers, an electrical insulation layer, HTS shield layers, and copper shield layers. 275 kV/3 kA class YBCO power cables may be subjected to a fault current of 63 kA(rms) for 0.6 s. Therefore, in order to ensure stability and feasibility of superconducting power cables, we need to investigate the thermal characteristics and current distribution in the cable under fault conditions. In this study, we performed numerical simulations on a YBCO model cable under fault conditions by using a computer program we developed on the basis of 3D finite element method (FEM) and electrical circuit model.

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    17
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  • Stability and Protection of Coils Wound With YBCO Bundle Conductor

    Hiroshi Ueda, Atsushi Ishiyama, Koji Shikimachi, Naoki Hirano, Shigeo Nagaya

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   20 ( 3 ) 1316 - 1319  2010.06  [Refereed]

     View Summary

    The thermal behavior of a high-temperature superconducting (HTS) coil is significantly different from that of a low-temperature superconducting (LTS) coil. A HTS conductor has a greater volumetric heat capacity at the operating temperature envisaged for practical applications. Therefore, a HTS coil is much less likely to be quenched than a LTS coil by mechanical disturbances such as the heat generated by the cracking of the impregnation material or by the friction resulting from wire movements. However, the HTS conductor is cyclically subjected to tensile strain because electrical charging and discharging are repeated in real applications involving the Superconducting Magnetic Energy Storage (SMES) system. The superconducting characteristics may locally deteriorate due to this cyclic strain. Therefore, to enhance the reliability and safety of the HTS coil, a quench protection scheme is needed. Because the normal-zone propagation velocity is quite low, detecting a non-recovering normal zone is difficult in HTS coils, and quenching produces excessive overheating that may cause the conductor to melt. In this study, we focus on a coil wound with a YBCO bundle conductor used in SMES applications and investigate the redistribution characteristics of the transport current in and the thermal behavior of the coil during a quench; we use a newly developed computer code based on the finite element method (FEM) and an equivalent circuit. We also discuss a protection scheme to dump the magnetic energy stored in the coils on an external resistance connected in parallel.

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    12
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  • Numerical Simulation of Critical Current Performance in Nb3Sn Strand Subjected to Periodic Bending Deformation

    Haruyuki Murakami, Hiroshi Ueda, Atsushi Ishiyama, Norikiyo Koizumi, Kiyoshi Okuno

    ELECTRICAL ENGINEERING IN JAPAN   171 ( 3 ) 7 - 15  2010.05  [Refereed]

     View Summary

    In the ITER Engineering Design Activity (EDA), four NB3Sn model coils were developed and successfully tested. However, it was revealed that the critical current of the conductor degraded with the increase of electromagnetic force. One of the explanations of this phenomenon is a strand bending caused by enormous electromagnetic force. The authors therefore developed a simulation code using the distributed circuit model to investigate dependency of the critical current performance on the periodic bending deformation. The simulation results were in good agreement with the experiments. The dependence of the critical current on the periodic transverse load, temperature, periodic load pitch, thickness of Ta barrier which prevents Cu stabilizer from being contaminated by Sn, twist pitch of the strand, and RRR of the bronze matrix was investigated using the developed code. The results showed that the critical current degraded less with decreasing the pitch of the transverse load and increasing the Ta barrier thickness. It suggests that the shorter cabling pitch and the larger bending stiffness prevent the critical current degradation. (C) 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(3): 7-15, 2010; Published online in Wiley Inter Science (www.interscience.wiley.com). DOI 10.1002/eej.20923

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  • Appropriate frequency band of event related desynchronization (ERD) for motor-image BCI

    Minoru Kawasaki, Hideki Nojo, Tetsu Jyo, Atsushi Ishiyama, Naoko Kasai, Yumie Ono

    NEUROSCIENCE RESEARCH   68   E327 - E327  2010  [Refereed]

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  • Development of (RE)BCO cables for HTS power transmission lines

    S. Mukoyama, M. Yagi, T. Masuda, N. Amemiya, A. Ishiyama, N. Kashima, S. Nagaya, Y. Aoki, M. Yoshizumi, Y. Yamada, T. Izumi, Y. Shiohara

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   469 ( 15-20 ) 1688 - 1692  2009.08  [Refereed]

     View Summary

    High-temperature Superconducting (HTS) power cables transmit bulk power with lower loss than conventional cables. Moreover, HTS cables are expected to be constructed as a new underground cable in urban areas at lower cost compared to a high voltage XLPE cable. To put promising HTS cables to practical use, we need (RE)BCO tapes with long length, high critical current, and low cost. Recently many organizations have improved the performance of the (RE)BCO tapes, such as YBCO tapes, or other coated conductor tapes that are made with a variety of different processes. We have fabricated the conductors for the HTS power cable that was constructed of different kinds of(RE)BCO tapes and measured the l(c) and AC losses. We achieved significantly low AC loss of 0.1 W/m at 1 kA in the HTS conductor using narrow slit tapes that were cut by laser. Moreover, a 20 m long HTS power cable model and a cable intermediate joint were developed. Short circuit current tests were conducted on the cable system that consisted of two 10 m cables, a cable joint, and two terminations. The cables and the joint withstood the short circuit current of 31.5 kA for 2 s without damage. (C) 2009 Elsevier B.V. All rights reserved.

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  • Over-current characteristics of YBCO superconducting cable

    X. Wang, H. Ueda, A. Ishiyama, M. Yagi, S. Mukoyama, N. Kashima, S. Nagaya, Y. Shiohara

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   469 ( 15-20 ) 1717 - 1721  2009.08  [Refereed]

     View Summary

    To achieve large current capacity and high mechanical flexibility, YBa(2)Cu(3)O(7) (YBCO) superconducting cables consist of a number of YBCO coated conductors that are assembled and wound spirally on a Cu former. In practical applications, superconducting cables are vulnerable to short-circuit fault currents that are 10-30 times greater than the operating current. Therefore, in order to ensure the stability of YBCO superconducting cables in such a situation and to protect them from the fault currents, it is important to investigate the redistribution of the transport current and electromagnetic coupling between the conductor layer, shield layer, and Cu former. In this study, we carried out experiments on a 10-m-long YBCO model cable, which was manufactured by Furukawa Electric. An over-current with a peak of 31.8 kA(rms) and a duration of 2.02 s was applied to the model cable. We performed numerical simulations using a novel computer program developed using the 3D finite element method to elucidate the electromagnetic and thermal behavior of the YBCO model cable in the presence of an over-current. (C) 2009 Published by Elsevier B.V

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    4
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  • Over-Current Characteristics of a 20-m-Long YBCO Model Cable

    Xudong Wang, Hiroshi Ueda, Atsushi Ishiyama, Masashi Yagi, Shinichi Mukoyama, Masayoshi Ohya, Takato Masuda, Naoji Kashima, Shigeo Nagaya, Yuh Shiohara

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   19 ( 3 ) 1722 - 1726  2009.06  [Refereed]

     View Summary

    To achieve large current capacity and mechanical flexibility, high-temperature superconductor (HTS) power transmission cables consist of a number of YBCO coated conductors, which are assembled and wound spirally on a Cu former. In practical applications, superconducting cables might be subjected to short-circuit fault currents that are 10 to 30 times the operating current. Therefore, in order to ensure the stability and feasibility of HTS power cables and protect them from fault currents, it is important to estimate the redistribution of the transport current and electromagnetic coupling among the conductor layer, shield layer, and Cu former. In this study, we carried out experiments on a 20-m-long YBCO model cable, which was composed of two jointed 10-m-long YBCO model cables. Over-current with a peak of 31.8 kA(rms) and a duration of 2.02 s was applied to the model cable. We performed numerical simulations using a newly developed computer program based on the 3D finite element method (FEM) in order to clarify the electromagnetic and thermal behaviors of the YBCO model cable in the presence of an over-current.

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  • Accurate Position Control of Active Magnetic Levitation Using Sphere-Shaped HTS Bulk for Inertial Nuclear Fusion

    Yoshihiro Ishigaki, Hiroshi Ueda, Koh Agatsuma, Atsushi Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   19 ( 3 ) 2133 - 2136  2009.06  [Refereed]

     View Summary

    We have been developing an active magnetic levitation system, which is composed of a field-cooled disk-shaped or sphere-shaped high-temperature superconducting bulks (HTS bulks) and vertically piled ring-shaped electromagnets without an iron core. We suppose that this active magnetic levitation system can be applied to inertial nuclear fusion. In inertial nuclear fusion, one of the most important issues is to achieve high-accuracy position control of the fusion fuel, which consists of deuterium and tritium in order to evenly illuminate the entire surface of the target. Therefore, active magnetic levitation is applied to the levitation and position control of a sphere-shaped superconducting capsule containing nuclear fusion fuel. In this study, we designed and constructed a three-coil position control system in order to achieve the stable levitation of the sphere-shaped HTS bulk with a diameter of 5 mm by using the numerical simulation based on the hybrid finite element and boundary element analysis. Then, we carried out the experiments on the position control and restoring force characteristics of the sphere-shaped HTS bulk in the constructed levitation system.

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    5
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  • Design and Test of Filter of High Gradient Magnetic Separation System for Trapping Immunoglobulin in Serum

    Hiroshi Ueda, Koh Agatsuma, Kazuhiro Kajikawa, Mitsuho Furuse, Shuichiro Fuchino, Atsushi Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   19 ( 3 ) 2157 - 2161  2009.06  [Refereed]

     View Summary

    Recently, affinity magnetic beads have been widely used in immunomagnetic cell sorting (IMCS) technology. Today, we can easily sort and analyze DNA and antibodies (immunoglobulin) using various types of affinity magnetic beads available in the market. The diameters of these affinity magnetic beads used in immunomagnetic cell sorting are limited to above approximately 1 because of the low magnetic fields induced by permanent magnets. Now, nano-sized affinity magnetic beads are strongly desired to achieve high resolutions. We have been studying and attempting to develop a high-gradient magnetic separation (HGMS) system that employs a superconducting magnet to induce a considerably higher magnetic field than that induced by a permanent magnet in order to trap smaller nano-sized affinity magnetic beads by a filter made of fine stainless steel wool. In this study, we constructed a prototype of a desktop-type HGMS system using a cryocooler-cooled LTS magnet and conducted preliminary experiments on trapping the nano-sized magnetic particles. Furthermore, we investigated the magnetic field distribution and magnetic force around a magnetic wire in the filter by means of a numerical simulation.

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    20
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  • Radioactivity of YBCO and Bi-2223 Tapes Under Low Energy Neutron Flux

    Hiroshi Ueda, Atsushi Ishiyama, Nobuyuki Miyahara, Naoji Kashima, Shigeo Nagaya

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   19 ( 3 ) 2872 - 2876  2009.06  [Refereed]

     View Summary

    The quality of high-temperature superconductors ( HTSs) is rapidly increasing, and they can be used in power systems such as SMES systems and in industries as Si single-crystal growth pullers. In the future, HTS conductors are expected to be used for the magnets in nuclear fusion reactors or accelerators. In such applications, HTS conductors will be exposed to radiation. As a result, HTS conductors become radioactive making the operation and maintenance of the reactors or accelerators difficult; this also leads to an increase in the amount of nuclear waste generated. Therefore, we carry out experiments on the radiation damage in HTS conductors to study the characteristics of HTS conductors in radiation environments and to create an industrial database of the radiation effects on HTSs. We also carry out radioactive analyses on HTS conductors in order to clarify the relationship between the irradiation dose and the activity of HTS conductors. In this study, we prepared YBCO and Bi-2223 tapes and carried out the following preliminary experiments: ( a) irradiation of the sample HTS tapes with 2-MeV neutrons at room temperature without transport current and (b) study of neutron-induced radioactivity by gamma-ray spectrometry using a Ge detector after the irradiation.

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  • Degradation Characteristics of YBCO-Coated Conductors Subjected to Overcurrent Pulse

    Atsushi Ishiyama, Yukiyasu Nishio, Hiroshi Ueda, Naoji Kashima, Masami Mori, Tomonori Watanabe, Shigeo Nagaya, Masashi Yagi, Shinichi Mukoyama, Takato Machi, Yuh Shiohara

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   19 ( 3 ) 3483 - 3486  2009.06  [Refereed]

     View Summary

    YBCO tapes are expected to be used in future high temperature superconducting (HTS) applications because of their good characteristics at high temperatures and in high applied magnetic fields. In applications to electric power devices such as transmission cables, transformers, and fault current limiters, the HTS conductors will be subjected to short-circuit fault currents that are 10 to 30 times the normal operating current. These overcurrents are greater than the critical current, and degrade or burn-out the HTS conductors. Therefore, it is important to clarify the mechanism of the degradation caused by such overcurrent pulses. We carried out preliminary experiments on damage caused by overcurrent pulse drive, focusing on the temperature limitation without suffering degradation for overcurrent pulse operation. A 10-mm-wide YBCO tape was cut into 2-mm-wide sample tapes by a laser beam, and the sample tapes were soldered on silver-deposited 100-thick copper plates. Overcurrent tests were carried out on these sample tapes and I(c) degradation was investigated. In addition the contact interface between YBCO and the Ag layer or buffer layer before and after the overcurrent drives has been investigated in order to clarify the correlation between the degradation and delamination of sample tapes.

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    17
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  • Increase of frontal delta activity related to perceptual switching

    Mayuko Okada, Yumie Ono, Atsushi Ishiyama, Naoko Kasai

    NEUROSCIENCE RESEARCH   65   S174 - S174  2009  [Refereed]

    DOI

  • Over-current characteristics of superconducting model cable using YBCO coated conductors

    A. Ishiyama, X. Wang, H. Ueda, M. Yagi, S. Mukoyama, N. Kashima, S. Nagaya, Y. Shiohara

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   468 ( 15-20 ) 2041 - 2045  2008.09  [Refereed]

     View Summary

    For the application to power transmission cables, a number of YBCO tapes would be assembled and wound in spiral on a Cu-former. YBCO tapes and the Cu-former are connected in parallel and they might be subjected to short-circuit fault currents 10-30 times the operating current. In this study, we constructed a 1 m long YBCO model cable. Over-current with a peak of 31.5 kArms and a duration of 2.0 s, which was established by JEC (Japanese Electrotechnical Committee), was applied to this cable in a liquid nitrogen bath. The redistribution of the transport current between YBCO tapes and the Cu-former were examined by using Hall sensors. The numerical simulations were carried out using a newly developed computer program based on the 3D finite element method (FEM) in order to clarify the over-current characteristics in the cable. From the comparison of the experimental and simulation results, the validity of the developed computer program was confirmed. Therefore, we performed the simulations of a 10 m long model cable when carrying a fault current of 31.5 kArms applied for a durations of 2.0 s, and also estimated the influence of the cross-section area of the Cu-former and the Cu shield layer on the thermal behavior of the model cable by using the developed computer program. (C) 2008 Elsevier B.V. All rights reserved.

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    12
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  • 数値シミュレーションによるNb3Sn素線の波状曲げ変形時の超電導特性の評価

    村上陽之, 植田浩史, 石山敦士, 小泉徳潔, 奥野清

    電気学会論文誌B(電力・エネルギー部門誌)   128-B ( 6 ) 853 - 859  2008.06  [Refereed]

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  • Numerical simulation of critical current degradation of Nb3Sn strand in CIC conductor

    Haruyuki Murakami, Atsushi Ishiyama, Hiroshi Ueda, Norikiyo Koizumi, Kiyoshi Okuno

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   18 ( 2 ) 1051 - 1054  2008.06  [Refereed]

     View Summary

    The critical current of the ITER model coil degraded with an increase in the electromagnetic force. Experiments in which a periodic transverse load was artificially applied to a single coil strand showed this degradation. However, since these experiments were carried out under a certain condition, a general relation between the transverse load and the critical current was not obtained. Therefore, we have developed a numerical simulation code to investigate this general relation. The results of the numerical simulations are in good agreement with the experiments. This indicates that our numerical code is valid for the evaluation of the critical current performance of strands in CIC conductor. Next, the general dependence of the critical current degradation on Ta barrier thickness and resistivity of bronze was evaluated by using the developed simulation code. The results of the calculation showed that the Ta barrier thickness affects the critical current characteristics because of the large flexural rigidity of Ta barrier. On the other hand, the resistivity of bronze and the twist pitch of the filament rarely affect the critical current degradation since current transfers between filaments do not occur within the practical resistivity range of bronze.

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    2
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  • Transient stability characteristics of a 1-m single-layer YBCO cable

    Atsushi Ishiyama, Xudong Wang, Hiroshi Ueda, Masashi Yagi, Shinichi Mukoyama, Naoji Kashima, Shigeo Nagaya, Yuh Shiohara

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   18 ( 2 ) 1228 - 1231  2008.06  [Refereed]

     View Summary

    YBCO tapes are expected to be used in future high temperature superconductor (HTS) applications as they have better J(c) characteristics at high temperatures and in high magnetic fields. For power applications such as transmission cables, YBCO tapes and a copper former are connected in parallel and they might be subjected to a short-circuit fault current that is 10 to 30 times the normal operating current. Therefore the over-current behavior, including the hot-spot and the distribution of transport current between the copper-laminated YBCO tapes and the copper former, is very important to examine the stability and feasibility of the cable. This paper describes the experimental results for over-current pulses of a 1-m single-layer cable fabricated with five copper-laminated YBCO tapes and a copper former. Further, we performed numerical simulations by using a newly developed computer program based on the 3D finite element method.

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    13
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  • Magnetoencephalography: Basic theory and estimation techniques of working brain activity

    Yumie Ono, Atsushi Ishiyama

    Novel Trends in Brain Science: Brain Imaging, Learning and Memory, Stress and Fear, and Pain     77 - 93  2008  [Refereed]

     View Summary

    It is widely accepted that magnetoencephalography (MEG) is a promising tool for investigating human brain activity in good temporal and spatial resolution. However, the use of MEG is currently quite limited, mostly due to excessive diversity in localization techniques to estimate regional brain activity using MEG data. Because source localization in MEG is an ill-posed problem, an adequate localization technique varies depending on the task design and the timing of interest in MEG signals, which sometimes confuses investigators when choosing an analysis technique or comparing the results with those obtained with other modalities, such as functional magnetic resonance imaging. This chapter reviews the introductory theories and applications of currently available MEG source localization techniques as well as principles of MEG signals and its measurement for beginners and possible future MEG users. The physiological and mathematical backgrounds of cerebral MEG source are briefly introduced followed by the technical requirements for MEG data acquisition. Modern localization techniques for inverse problem solving with MEG, from a simple dipole model to an underdetermined type of norm estimation or spatial filter technique, are thoroughly described.

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    1
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  • Visualization of Normal-zone initiation and Propagation using Fluorescent Paints

    A. Ishiyama, H. Murakami, M. Tsuchiya, H. Ueda, H. Kato, K. Nara, Y. Shiohara

    8TH EUROPEAN CONFERENCE ON APPLIED SUPERCONDUCTIVITY (EUCAS'07)   97  2008  [Refereed]

     View Summary

    To establish a stability criterion for Yttrium barium copper oxide (YBCO)-coated conductors, it is necessary to clarify their transient thermal characteristics. Thermocouple thermometers, resistance thermometers, or the relation between the temperature and resistance of the stabilizer used for the conductors are generally employed for measuring their temperatures. However, these methods can only be employed to observe fixed-point data. Hence, it is difficult to observe the longitudinal and transversal distributions of temperatures in coated conductors. In this study, we adopt a method for the visualization of the temperature distribution of coated conductors by using fluorescent paints whose color changes with temperature. By adopting this method, we can measure the two-dimensional distribution of temperature in magnetic fields and at cryogenic temperatures. Therefore, local heat generation in the YBCO tapes can be observed with a higher spatial resolution and the uniformity in the critical current density of YBCO tapes can be identified. In this paper, we describe the developed thermal visualization system and the preliminary experimental results of the visualization of normal-zone initiation and propagation in YBCO sample strips. Further, we also report a part of the normal-zone initiation and propagation mechanism by electromagnetic field and heat transfer analyses by employing a three-dimensional finite element method (FEM).

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  • Position control of active magnetic levitation using sphere-shaped HTS bulk for inertial nuclear fusion

    K. Suga, K. Riku, K. Agatsuma, H. Ueda, A. Ishiyama

    8TH EUROPEAN CONFERENCE ON APPLIED SUPERCONDUCTIVITY (EUCAS&apos;07)   97  2008  [Refereed]

     View Summary

    We have developed an active magnetic levitation system that comprises a field-cooled disk-shaped or sphere-shaped HTS bulk and multiple ring-shaped electromagnets. In this system, the levitation height of HTS bulk can be controlled by adjusting the operating current of each electromagnet individually. Further, the application of the vertical noncontact levitation system is expected due to its levitation stability without mechanical supports. We assume that this system is applied to inertial nuclear fusion. However, one of the important issues is to achieve position control with high accuracy of the fusion fuel in order to illuminate the target evenly over the entire surface. Therefore, this system is applied to the levitation and position control of a sphere-shaped superconducting capsule containing nuclear fusion fuel. In this study, we designed and constructed a position control system for the sphere-shaped HTS bulk with a diameter of 5 mm by using numerical simulation based on hybrid finite element and boundary element analysis. We then carried out the experiment of levitation height and position control characteristics of the HTS bulk in this system. With regard to position control, accuracies within 59 mu m are obtained.

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  • Fatigue tests of YBCO coated conductors

    S. Bamba, Y. Tanaka, T. Ando, H. Ueda, A. Ishiyama, Y. Yamada, Y. Shiohara

    8TH EUROPEAN CONFERENCE ON APPLIED SUPERCONDUCTIVITY (EUCAS'07)   97  2008  [Refereed]

     View Summary

    In this paper, we report the fatigue characteristics of IBAD/PLD YBCO coated conductors. A YBCO coated conductor used in the superconducting coil of a SMES system is repeatedly subjected to mechanical tensile or compressive strain due to the Lorentz force during electrical charging or discharging. The superconducting characteristic of this conductor may deteriorate because of this cyclic strain. Therefore, it is necessary to investigate the effect of cyclic strain on the superconducting characteristics of YBCO coated conductors that have a laminated structure. We developed an experimental apparatus with a U-shaped sample holder in order to apply cyclic strain to the sample tape. This apparatus was used to perform the fatigue tests on YBCO coated conductors in liquid nitrogen in the absence of an external magnetic field. The strain cycles with the maximum strain epsilon(max) (zero external strain -&gt; epsilon(max) -&gt; zero external strain) were applied and repeated up to 5000 times, and the I-c measurements were performed at epsilon(max). Therefore, the application of cyclic strain with emax ranging from 0.3% to 0.5% did not result in any significant deterioration of the superconducting characteristics of the conductor.

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    3
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  • Overcurrent Characteristics of 1 m Long Superconducting Model Cable using YBCO Coated Conductors

    H. Ueda, X. Wang, A. Ishiyama, S. Mukoyama, M. Yagi, N. Kashima, S. Nagaya, Y. Shiohara

    8TH EUROPEAN CONFERENCE ON APPLIED SUPERCONDUCTIVITY (EUCAS'07)   97 ( 15-20 ) 2041 - 2045  2008  [Refereed]

     View Summary

    In applications to power transmission cables, a number of YBCO tapes would be assembled and wound spirally on a Cu former. The YBCO tapes and the Cu former would be connected in parallel and could be subjected to short-circuit fault currents 10 to 30 times the operating current. The fault currents would drive the YBCO tapes into the normal state and thus generate Joule heating for the duration of the fault. Therefore, in order to examine the stability and feasibility of YBCO power transmission cables, it is important to demonstrate the redistribution of the transport current and the electromagnetic coupling between the YBCO tapes and the Cu former during a short-circuit fault current. We constructed a 1 m long superconducting model cable and subjected it to an overcurrent with a peak of 31.5 kA(rms) for a duration of 2.0 s, as established by JEC (Japanese Electrotechnical Committee), in a liquid nitrogen bath. We examined the redistribution of the transport current between the YBCO sample tapes and the Cu former by using Hall probes. In addition, we developed a novel computer code based on the finite element method and an equivalent circuit in order to clarify the characteristics of the redistribution of the transport current and the thermal behaviour within the cable. Finally, we designed a 10 m long cable that would reach the degradation temperature of the YBCO tape due to the fault currents.

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    1
    Citation
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  • Recent development of an HTS power cable using YBCO tapes

    M. Yagi, S. Mukoyama, H. Hirano, N. Amemiya, A. Ishiyama, S. Nagaya, N. Kashima, Y. Shiohara

    PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS   463   1154 - 1158  2007.10  [Refereed]

     View Summary

    Overcurrent characteristics and reduction of AC loss are essential for high temperature superconducting (HTS) cable in a real grid. AC loss in an HTS conductor using YBCO could be potentially small but protection for overcurrent was needed.
    A 0.1 mm thick copper tape soldered to the YBCO tape was effective as protection from overcurrent and did not affect the increase in AC loss. The 2 m HTS conductor with Cu strands of 250 mm(2) and YBCO tapes with copper was fabricated. This conductor could withstand overcurrent of 31.5 kA for 2 s.
    To reduce AC loss, 10 mm wide YBCO tapes were divided into five strips using YAG laser. Using narrower strips and decreasing the space between the strips were effective in reducing AC loss. In consideration of this configuration, a three-layer conductor was fabricated, and AC loss of 0.054 W/m at 1 kA rms was achieved even though it had a small outer diameter of 19.6 turn. (C) 2007 Elsevier B.V. All rights reserved.

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    14
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  • Inverse solution for time-correlated multiple sources using Beamformer method

    Takeshi Kimura, Masahiro Kako, Hiromi Kamiyama, Atsushi Ishiyama, Naoko Kasai, Yutaka Watanabe

    International Congress Series   1300   417 - 420  2007.06  [Refereed]

     View Summary

    The Adaptive Beamformer draws attention as an MEG inverse solution for multiple sources. The method has a drawback that we cannot apply it to the temporally correlated sources. We had developed a method to overcome this drawback. Signal-subspace eigenvectors of an original data-covariance matrix was decomposed by the GA-SA method (the hybrid method of Genetic Algorithm and Simulated Annealing) and a new decorrelated data-covariance matrix was reconstructed. The GA-SA method, however, requires the number of components of the eigenvector as a foreknowledge. In this study, we introduced the minimum-norm method, that requires no foreknowledge, instead of the GA-SA method. We carried out a three-dimensional simulation study using the proposed method, and applied to the auditory evoked response field measured by using the Vectorview system. As a result, multiple sources with time-correlations were successfully estimated. © 2007 Elsevier B.V. All rights reserved.

    DOI

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    5
    Citation
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  • Numerical simulation of critical current and n-value in Nb3Sn strand subjected to bending strain

    Haruyuki Murakami, Atsushi Ishiyama, Hiroshi Ueda, Norikiyo Koizumi, Kiyoshi Okuno

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   17 ( 2 ) 1394 - 1397  2007.06  [Refereed]

     View Summary

    Critical current of ITER model coil degraded with the increase of electromagnetic force. Analysis based on results of the experiments in which periodic transverse load is artificially applied to single strand showed that periodic bending of the strand by transverse load caused this degradation. However, since the experiments were carried out under a certain condition, general relation between transverse load and critical current was not obtained. We have therefore developed a numerical simulation code to investigate the general relation. However, there were some disagreements between the simulation and experimental results in our previous study. Our simulation model was consequently modified, resulting in good agreement with the test results. The general dependence of the critical current on periodic transverse load, temperature, and pitch of periodic load is investigated using the modified simulation code. The simulation results reveal that the reduced critical current depends on the temperature, and is a function of the bending strain independent of the pitch of the periodic load.

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    19
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  • Transient stability characteristics of parallel-connected YBCO coated conductors for power transmission cables

    Atsushi Ishiyama, Takuya Iwata, Hiroshi Ueda, Shinichi Mukoyama, Yuh Shiohara

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   17 ( 2 ) 1672 - 1675  2007.06  [Refereed]

     View Summary

    YBCO coated conductors are expected to be used in future high-temperature superconductor applications. For the application to power transmission cables, a number of YBCO coated conductors would be connected in parallel and they might be subjected to short-circuit fault currents. Therefore, in order to examine the stability and feasibility of YBCO power transmission cables, it is important to investigate the normal-zone initiation and propagation characteristics of the YBCO tapes and demonstrate the redistribution of transport current and the electromagnetic coupling between YBCO tapes during a short-circuit fault current. In this study, over-current pulses were applied to the two parallel-connected YBCO sample tapes in a liquid nitrogen bath, and the characteristics of the normal-zone initiation and propagation were examined experimentally. Additionally, we also show the experimental results of the redistribution of the transport current between parallel-connected YBCO sample tapes.

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    15
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  • Development of pipeline transporter system using pinning effect of high-temperature superconducting bulks

    Hiroshi Ueda, Motokazu Tsuchiya, Atsushi Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   17 ( 2 ) 2323 - 2326  2007.06  [Refereed]

     View Summary

    We have been developing a pipeline transporter system using high-temperature superconducting bulks (HTS bulks). In this paper, we propose a pipeline transporter system using pinning effect of HTS bulks. This system has the advantage of the application in harsh or dangerous environment such as in hazardous gas. This system requires large lateral force at the certain gap between the permanent magnets and the HTS bulks. For the realization of this pipeline transporter system, we investigated the influences of the arrangement of HTS bulks and permanent magnets on the lateral force characteristics through experiments and numerical simulations by using a computer program based on the three-dimensional hybrid finite element and boundary element (3D hybrid FE-BE) method. And we also designed a model system with a lateral force of 1500 N.

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    7
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  • A criterion for determining stabilizer thickness of YBCO coated conductors based on coil protection

    Atsushi Ishiyama, Hiroshi Ueda, Taketoshi Ando, Hironori Naka, Sadanori Bamba, Yuh Shiohara

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   17 ( 2 ) 2430 - 2433  2007.06  [Refereed]

     View Summary

    The purpose of this study is to propose a criterion for determining stabilizer thickness of YBCO coated conductors. The permissible disturbance energy density in high-temperature superconductors (HTSs) is two or three orders of magnitude greater than that in low-temperature superconductors (LTSs). On the other hand, to enhance the reliability and safety of HTS coils, an establishment of a protection scheme assuming a quench caused by a failure in power supply, cooling system or similar problem is also required for HTS coil systems. Quenching produces excessive temperature or voltage in the coil winding; overheating may cause the conductor to meltdown, or high voltage may punch a hole in the winding. To avoid these types of damages in YBCO coils, a suitable stabilizer thickness must be determined for the sophisticated structure of YBCO coated conductors, which are composed of highly textured thin-film on a flat flexible substrate. Therefore, we investigate the appropriate structure for YBCO coated conductors from the perspective of energy dumping (i.e., quench protection). Based on the protection scheme that the stored magnetic energy in the coils is dumped by an external dump resistance prepared as a quench protection, we derive a function that examines the heat balance of a quenching YBCO coil in an adiabatic condition and propose a criterion using the function to determine an appropriate stabilizer thickness for YBCO coated conductors.

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    38
    Citation
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  • Asymmetrical normal zone propagation analysis considering Hall effect for large aluminum stabilized superconductor

    So Noguchi, Nobuki Kawawada, Hajime Igarashi, Atsushi Ishiyama, Nagato Yanagi, Shinsaku Imagawa

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   17 ( 2 ) 2490 - 2493  2007.06  [Refereed]

     View Summary

    Aluminum stabilized superconductors are used in accelerators, SMES, and fusion devices, such as the LHD helical coils. These superconductors have large cross-sectional area of high purity aluminum to improve their stability. However, one of the important properties of these superconductors is the transient stability, which is caused by a long duration of transport current transfer from the superconducting strands into the aluminum in a normal state region. Once a normal zone is initiated in such superconductors, excess joule heat is generated in a small region of the aluminum stabilizer near the superconducting strands during the transport current diffusion time. It hence deteriorates the transient stability. Therefore, it is important to investigate the characteristics of the transient stability by numerical analysis. The latest experiments of the LHD helical coil conductor showed an asymmetrical propagation of normal zone along the longitudinal direction of the conductor. The Hall effect is clearly one of the causes of this phenomenon. The Hall effect prevents the transport current from transferring between the superconducting strands and the aluminum stabilizer. It causes the asymmetrical transport current distribution, and affects the stability of the superconductor. In order to simulate the normal zone propagation in the superconductor more precisely and to clarify the cause of the asymmetrical propagation, we have developed a 2D finite element analysis code taking account of the Hall effect and investigated the characteristics of the normal zone propagation of large aluminum stabilized superconductors.

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    3
    Citation
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  • Degradation of YBCO coated conductors due to over-current pulse

    Atsushi Ishiyama, Yasutake Tanaka, Hiroshi Ueda, Yuh Shiohara, Takato Machi, Yasuhiro Iijima, Takashi Saitoh, Naoji Kashima, Masami Mori, Tomonori Watanabe, Shigeo Nagaya

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   17 ( 2 ) 3509 - 3512  2007.06  [Refereed]

     View Summary

    For HTS (High-Temperature Superconductor) applications to electric power devices, superconductors are subjected to short-circuit fault currents 10 to 30 times the normal operating current. These over-currents will drive the HTS conductors normal and degrade or burn-out the HTS conductors. Therefore it is important to establish a novel thermal stability criterion for over-current pulse drive.
    In this study, we carried out preliminary experiments on the damage caused by over-current pulse drive focusing on the limitation of the temperature rise without degradation. We prepared five YBCO sample tapes fabricated with IBAD/PLD and IBAD/MOCVD methods. Measurements were performed at 60 K and 80 K (Conduction cooling with Gifford-McMahon cryocooler was adopted) in self-field.
    The experimental results indicated that the degradation of the sample tapes for the over-current pulse with a duration of 1 second depended on not the initial critical current I-c, but the peak temperature T-peak. The permissible peak temperature without degradation existed at about 400-600 K. The sample tapes were also observed before and after the experiments by magneto-optic (MO) imaging to find the distribution of degradation area.

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    29
    Citation
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  • Influence of bending and torsion strains on critical currents in YBCO coated conductors

    Tomoaki Takao, Tsutomu Iwamura, Yuta Fukasawa, Shigetoshi Minowa, Hidenori Sato, Takashi Asano, Atsushi Ishiyama, Junko Kato, Takato Machi, Koichi Nakao, Yu Shiohara

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   17 ( 2 ) 3513 - 3516  2007.06  [Refereed]

     View Summary

    A YBCO coated conductor is expected to be a next generation high performance superconductor. To design superconducting machines using YBCO conductors, evaluation of not only superconducting properties but also mechanical properties is very important. Hence, we applied bending and torsion to the YBCO conductor and measured degradation of the conductor against the strain. To compare with the YBCO's data, a Bi2223 conductor was also tested under the same experimental condition. From the bending test, degradation of the Bi conductor was faster than that of the YBCO conductor and the critical current gradually decreased with increasing bending strain. The YBCO conductor kept better performance than the Bi conductor, and degradation suddenly occurred. And when the superconducting layer in the YBCO conductor was subjected to compressive strain in the bending test, the critical current hardly decreased at approximately one percent of the bending strain.

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    23
    Citation
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  • Characteristics of Compressive strain and superconducting property in YBCO coated conductor

    Tomoaki Takao, Sho Koizuka, Kazuki Oi, Atsushi Ishiyama, Junko Kato, Takato Machi, Koichi Nakao, Yu Shiohara

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   17 ( 2 ) 3517 - 3519  2007.06  [Refereed]

     View Summary

    We have applied compressive stress perpendicular to YBCO coated tapes, and measured the degradation of critical currents. When the tape was pushed from the silver surface of the tape, the performance of the tape hardly decreases. On the other hand, compressing from the hastelloy face, degradation of the tape occurred. We observed the damage of the tapes by a magneto-optical imaging technique. The observed results were consistent with the degradation data. From those results, we think that it is better not to compress strongly from the hastelloy side.

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    21
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  • Assessment of cryogenic thermography system using commercial fluorescent paints on their applicability to visualization of normal-zone propagation in YBCO coated conductor

    Atsushi Ishiyama, Motokazu Tsuchiya, Hiroshi Ueda, Yuh Shiohara

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   17 ( 2 ) 3765 - 3768  2007.06  [Refereed]

     View Summary

    To establish a stability criterion for YBCO coated conductors, it is required to clarify their transient thermal characteristics. In this study, we adopt a method for visualization of. temperature distribution using fluorescent paints whose color changes depending on the temperature. In the visualization method, firstly, commercial fluorescent paints are coated on the surface of sample strips. And then, the sample is irradiated by a black light or UV-LEDs, and the image of the fluorescence is observed by a CCD camera. These captured images are manipulated image processing by a computer, and show the temperature distribution. This system can be applied to cryogenic and high magnetic field circumstances. By adopting this visualization method to the investigation of transient thermal characteristics of YBCO tapes, local heat generation in the YBCO tapes can be observed by higher resolution, and it is expected to identify the uniformity of critical current density of YBCO tapes. In this paper, we describe the developed thermal visualization system and the preliminary experimental results on visualization of normal-zone initiation and propagation in YBCO sample strip fabricated with IBAD/PLD method.

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    9
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  • 3D electromagnetic analysis of levitating transporter using bulk superconductor

    Hiroshi Ueda, Satoshi Azumaya, Satoshi Tsuchiya, Atsushi Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   16 ( 2 ) 1092 - 1095  2006.06  [Refereed]

     View Summary

    We have constructed and demonstrated levitating transporter models composed of the superconductor bulks (HTS bulks) and permanent magnets. The dynamic characteristics of lift force, lateral force and magnetic stiffness are very important for the design of superconducting devices such as a levitation system. The electromagnetic phenomenon should be clarified through the accurate analyses of the magnetic field and shielding current distributions within HTS bulks. In this study, we developed a new simulation program based on the three-dimensional hybrid finite element and boundary element (3D hybrid FE-BE) method, which combines with the fast multipole method (FMM). By using the FMM, it is possible to solve the large-scale problem with a reduction of the required memory size and improvement of the accuracy. This simulation program can consider the anisotropic and nonlinear E - J characteristics of HTS bulks. The results of experiment and numerical simulation are in good agreement.

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    36
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  • Transient stability analysis taking into account Hall effect for large aluminum stabilized superconductor

    Nobuki Kawawada, So Noguchi, Hajime Igarashi, Atsushi Ishiyama, Nagato Yanagi, Shinsaku Imagawa

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   16 ( 2 ) 1717 - 1720  2006.06  [Refereed]

     View Summary

    Aluminum stabilized superconductors are used in accelerators, SMES, and fusion devices, such as the LHD helical coils. These superconductors have large-cross sectional area of high purity aluminum to improve their stability. However, one of the important properties of these superconductors is the transient stability, which is caused by a long duration of transport current transfer from the superconducting strands into the aluminum in a normal-state region. Once a normal zone is initiated in such superconductors, excess joule heat is generated in a small region of the aluminum stabilizer near the superconducting strands during the transport current diffusion time. It hence deteriorates the transient stability. Therefore, it is important to investigate the characteristics of the transient stability by numerical analysis. The latest experiments of the LHD helical coil conductor show an asymmetrical propagation of normal zone along the longitudinal direction of the conductor.
    The Hall current generation is clearly one of the causes of this phenomenon. The Hall current generation prevents the transport current from transferring between the superconducting strands and the aluminum stabilizer. It causes the asymmetrical transport current distribution, and affects the stability of the superconductor. In order to simulate the normal-zone propagation in the superconductor more preciously and to clarify the cause of the asymmetrical propagation, we have developed a 2D finite element analysis code taking account of the Hall effect and investigated the transient stability of large aluminum stabilized superconductors.

    DOI

    Scopus

    7
    Citation
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  • Numerical simulation of the critical current and n-value in Nb3Sn strand subjected to bending strain

    Masayuki Hirohashi, Haruyuki Murakami, Atsushi Ishiyama, Hiroshi Ueda, Norikiyo Koizumi, Kiyoshi Okuno

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   16 ( 2 ) 1721 - 1724  2006.06  [Refereed]

     View Summary

    To demonstrate the applicability of Nb3Sn Cable in Conduit Conductors (CICC's) to International Thermonuclear Experimental Reactor (ITER) coils, four Nb3Sn model coils have been constructed and tested. The experimental results showed that the measured critical current of the conductors degraded compared with what is expected from the ability of the strands. In addition, the larger is the applied electromagnetic force, the larger the magnitude of the degradation is. A degradation in n-value was also observed. One of the explanations of this degradation is supposed to be a local strand bending. This consideration has been supported by test results, in which a similar degradation in the critical current and n-value was observed when applying periodic bending strains to a single strand. However, general dependence of critical current on periodic bending strain has not been clarified in this test since the experiments were carried out at a certain magnetic field, temperature and strain. Therefore, a numerical simulation code was developed to study the general dependence of the critical current and n-value of Nb3Sn strand on periodic bending strain. A distributed constant circuit model is applied to simulate current transfer among the filaments in the strand. The simulation results show relatively good agreement with the experimental results but some modification in modeling is required for more accurate simulation.

    DOI

    Scopus

    11
    Citation
    (Scopus)
  • Application to Coils

    ISHIYAMA Atsushi, NAGAYA Shigeo

    IEEJ Transactions on Sensors and Micromachines   126 ( 5 ) 286 - 287  2006.05

     View Summary

    This article has no abstract.

    DOI CiNii

  • A new analysis method for accurate supercurrent distribution inside high-temperature superconducting bulk

    Yanagawa Tomohiro, Kaneda Kazufumi, Ishiyama Atsushi, Noguchi So, Yamashita Hideo

    IEEE transactions on magnetics   42 ( 4 ) 751 - 754  2006.04

    DOI CiNii

    Scopus

    2
    Citation
    (Scopus)
  • Operational Characteristics of Linear Synchronous Actuator with Field-Cooled YBCO Bulk Secondary

    T. Shibata, H. Ueda, K. Agatsuma, A. Ishiyama

    7TH EUROPEAN CONFERENCE ON APPLIED SUPERCONDUCTIVITY (EUCAS'05)   43   975 - 978  2006  [Refereed]

     View Summary

    It is expected that electric devices would be high efficiency, high output and downsized by using high-temperature superconducting (HTS) bulk materials. In the previous study, we have fabricated and tested a linear synchronous actuator with double-sided primary and YBCO bulk secondary; the linear actuator consists of a field-cooled YBCO bulk for secondary (mover) and copper windings with an iron core as a primary. The primary, which was excited by a three-phase VVVF (variable voltage variable frequency) power source to generate sinusoidal traveling magnetic fields, was divided into two sections: 1) the starting section in which the secondary is accelerated as an induction machine; and 2) the synchronous section in which the secondary moves with a specified synchronous speed. And we have evaluated both of the static and dynamic characteristics on this linear synchronous actuator. However, for practical use of linear actuator with field-cooled HTS bulk secondary, it is required to examine the distribution of magnetic field within the HTS bulk which is exposed to the traveling magnetic field in a realistic operational environment of linear actuator. Therefore, in this study, we repeated the mode of acceleration, constant-speed, deceleration and stop with the control circuit in the synchronous section. The direction of the mover can be turned automatically by the switching device and it made round-trip running possible. Then, we carried out many times round-trip operations and evaluated the change of the magnetic field on the surface of the YBCO bulk in various conditions with trapped field of the secondary and traveling magnetic field generated by the primary windings.

    DOI

    Scopus

  • Position Control of Active Magnetic Levitation using YBCO Bulk and Multiple Electromagnets

    Y. Ito, H. Ueda, K. Agatsuma, A. Ishiyama

    7TH EUROPEAN CONFERENCE ON APPLIED SUPERCONDUCTIVITY (EUCAS'05)   43   987 - 990  2006  [Refereed]

     View Summary

    We have been developing an active magnetic levitation system composed of field-cooled disk-shaped YBCO bulk and multiple ring-shaped electromagnets which are vertically piled up. We have demonstrated and reported that the levitation height, as well as stability, can be remarkably improved by adjusting the operating current of each electromagnet individually. In this study, we constructed a noncontact position control system in the vertical direction based on the feedback control theory and the electromagnetic field analyses considering superconducting characteristics of the YBCO bulk. Depending on levitation height, the operating current in the electromagnets is controlled automatically. The system consists of two ring-shaped copper-winding electromagnets without iron core and a ring-shaped YBCO bulk magnetized by the field-cooling process. We carried out experiments to verify the feasibility of noncontact position control system. In the experiment for position control, the levitation height maintained a target position accurately, and responded smoothly to changing target position. In addition, we aimed at the construction of the position control system with higher accuracy using the numerical simulation based on the finite element method analyses. And, the position control system that piled up three electromagnets was designed and constructed. Concretely, accuracies of the position control within 28 mu m were obtained. Final goal of our study is to apply the levitation system to the inertial nuclear fusion in which the accuracy as high as several mu m would be required.

    DOI

    Scopus

  • An optimal configuration design method for HTS-SMES coils

    S Noguchi, A Ishiyama, S Akita, H Kasahara, Y Tatsuta, S Kouso

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   15 ( 2 ) 1927 - 1930  2005.06

     View Summary

    Recently, the properties of high temperature superconducting tapes have been in advance and high temperature superconducting magnets have been constructed and demonstrated. However, the high temperature superconducting tapes have different thermal characteristics compared with low temperature superconducting wires. Therefore, it is necessary to consider these characteristics of high temperature superconducting tapes at the magnet design stage. We proposed an optimal design method for superconducting coils wound with Bi2223/Ag tapes. In this paper, the configuration of 72 MJ SMES coils wound with Bi2223/Ag tapes are optimized.

    DOI

    Scopus

    39
    Citation
    (Scopus)
  • 空間・時間的相関に基づくMEGデータの信号源数推定

    星野大介, 小野弓絵, 石山敦士, 葛西直子, 外池光雄

    日本生体磁気学会誌   17 ( 2 ) 31 - 41  2005.03  [Refereed]

  • Non-invasive Cardiac Functional Mapping on Disease-model Mice - Development of High Spatial Resolution SQUID System for MCG on Mice -

    A Ishiyama

    Journal of the Cryogenic Society of Japan   40 ( 2 ) 44-50 - 50  2005.02  [Refereed]  [Invited]

    DOI CiNii

  • Trapped Field Characteristic of YBCO Bulk in AC External Magnetic Field

    UEDA Hiroshi, MORISAKI Tohru, ISHIYAMA Atsushi

    IEEJ Transactions on Power and Energy   124 ( 11 ) 1357 - 1364  2004.11

     View Summary

    Trapped field characteristics are one of the key factors in the application of high-temperature superconducting bulk, such as magnetic levitation systems, motors, bulk magnets and so on. The immutable trapped field is required in superconducting bulk applications as a quasi-permanent magnet, however, the trapped field is influenced and changed by a time-varying external magnetic field in a realistic operational environment of electrical devices. This means that shielding current distribution within the bulk is changed by the time-varying magnetic field and the transient magnetic flux movement results in temperature rise and finally reduction of the trapped field. In this study, we observed the abrupt reduction of the trapped field for the external AC magnetic field in the range of frequency up to 50 Hz. And we also performed the numerical simulation using a newly developed computer program based on the finite element method (FEM). In the simulation program, the voltage-current (E-J) characteristics, which depend on the irreversibility temperature are taken into account. From these results, it can be considered that the abrupt reduction of the trapped field is caused by the temperature rise due to AC loss.

    DOI CiNii

    Scopus

    3
    Citation
    (Scopus)
  • 着磁されたバルク超電導体の交流磁界印加特性

    植田浩史, 森崎徹, 石山敦士

    電気学会論文誌B   124-B ( 11 ) 1358 - 1364  2004.11  [Refereed]

  • YBCO線材の常電導転移・伝播特性評価

    石山敦士, 柳井正浩, 植田浩史, 飯島康裕, 斉藤隆, 塩原融

    低温工学   39 ( 11 ) 560 - 566  2004.11  [Refereed]

    DOI

  • Fundamental Characteristics and 3D Electromagnetic Analysis for Magnetic Levitation Transporter using YBCO Bulk Superconductors

    Hiroshi Ueda, Mami Iwamoto, Yuhya Kudo, Atsushi Ishiyama

    IEEJ Transactions on Power and Energy   124-B ( 10 ) 1220 - 1228  2004.10  [Refereed]

    DOI

  • Development of biomagnetic measurement system for mice with high spatial resolution

    Y Ono, A Ishiyama, N Kasai, K Chinone

    APPLIED PHYSICS LETTERS   85 ( 2 ) 332 - 334  2004.07  [Refereed]

     View Summary

    We have been developing a mice biomagnetic measurement system using a dc superconducting quantum interference device magnetometer for a comparative magnetoencephalogram study of transgenic and wild mice. In this study, we adopted a magnetometer with a pickup coil of 1.0 mm diameter and 0.7 mm lift-off distance to improve spatial resolution and magnetic field sensitivity. The magnetocardiogram of a wild mouse was measured as the initial application of the system. The bipolar peak positions in a magnetic field map separated by 5.6 mm were clearly detected with the maximum amplitude of 88 pT. (C) 2004 American Institute of Physics.

    DOI

    Scopus

    25
    Citation
    (Scopus)
  • Transient stability analysis of large aluminum stabilized superconductor by 2D and 3D finite element analysis

    Tomokazu Tsuchiya, So Noguchi, Hideo Yamashita, Atsushi Ishiyama, Nagato Yanagi, Toshiyuki Mito

    IEEE Transactions on Applied Superconductivity   14 ( 2 ) 1330 - 1333  2004.06  [Refereed]

     View Summary

    Very-large-current composite superconductors are used in SMES coils and fusion applications. These superconductors have large cross-sectional areas of high purity aluminum to improve their stability. Once a normal zone is initiated in such superconductors, the current transfers from the superconducting strands to the aluminum stabilizer according to the Maxwell's equations and the temperature distribution. However, the time constant of current diffusion in the aluminum stabilizer is very long as electrical resistivity of aluminum is very low. Therefore, excess Joule heating is generated in a small region of aluminum stabilizer near superconducting strands, and the temperature increases locally. Some 2D numerical analyses have been carried out in order to investigate the transient stability of the superconductor applied to the Helical Coil of LHD in National Institute for Fusion Science. But, as the performance of computers have improved, huge numerical simulations are new feasible. So we wrote a 3D finite element analysis code ourselves to carry out some now analyses that we compared with 2D analysis.

    DOI

    Scopus

    6
    Citation
    (Scopus)
  • Development of SMES for power system control

    Y. Tatsuta, S. Koso, H. Abe, M. Urata, H. Ohsaki, A. Ishiyama, S. Taniguchi, S. Nagaya, S. Akita, K. Terazono, N. Hirano, T. Semba, S. Hanai

    IEEE Transactions on Applied Superconductivity   14 ( 2 ) 693 - 698  2004.06  [Refereed]

     View Summary

    Since 1999, a Japanese national project to realize commercially feasible SMES for designated applications has been promoted. Model coils for power system stabilization, load fluctuation compensation and frequency control have been fabricated and tested. In this paper, we introduce the present status of the project, including feasibility studies of an HTS SMES.

    DOI

    Scopus

    21
    Citation
    (Scopus)
  • Dynamic characteristics and finite element analysis of a magnetic levitation system using a YBCO bulk superconductor

    H Ueda, A Ishiyama

    SUPERCONDUCTOR SCIENCE & TECHNOLOGY   17 ( 5 ) S170 - S175  2004.05  [Refereed]

     View Summary

    We have been developing a magnetic levitating device with two-dimensional movement, namely a 'levitating X-Y transporter'. For the real design of a levitating X-Y transporter, it is necessary to clarify the levitation characteristics, such as the lift, the levitation height and the stability against mechanical disturbances. Furthermore various kinds of force may be applied to the levitating part and cause mechanical oscillation. Therefore the characteristics of oscillation are also important factors in the dynamic stability of such a levitation system. In this paper, we examine experimentally the lift and the restoring force and develop a new simulation code based on the three-dimensional hybrid finite and boundary element method to analyse the dynamic electromagnetic behaviour of the HTS bulk. We have investigated a suitable permanent-magnet arrangement to enhance the levitation characteristics through experiment and numerical simulation. We can then determine the suitable conditions for stable levitation from those results.

    DOI

    Scopus

    27
    Citation
    (Scopus)
  • Preliminary experiments of a tubular linear actuator ion the vertical direction using YBCO bulk

    A Sugawara, H Ueda, A Ishiyama

    SUPERCONDUCTOR SCIENCE & TECHNOLOGY   17 ( 5 ) S176 - S179  2004.05  [Refereed]

     View Summary

    We have been developing a new type of active-maglev system composed of field-cooled disc-shaped YBCO bulk and multiple ring-shaped electromagnets, which are vertically piled up. One of the useful features of the active-maglev system is that the levitation height is adjustable by varying the operating current through an electromagnet. Maximum levitation height in stable levitation, however, is restricted by the magnetic field distribution produced by the electromagnet. To enhance the levitation height, we have fabricated and tested an active-maglev system with multiple ring-shaped electromagnets instead of using a larger single electromagnet. Up to now, we have reported the experimental results in a model active-maglev system composed of five electromagnets and showed that the levitation height, as well as stability, can be remarkably improved by adjusting the operating current of each electromagnet individually. In this study, we constructed a model system operated as a tubular linear synchronous actuator in the vertical direction in expectation of it being applied in factory automation upgrading. The primary consists of six ring-shaped copper-winding coils without iron core and is supplied with three-phase sinusoidal excitation. A disc-shaped YBCO bulk, which was magnetized by a field-cooling process, was adopted as a secondary (mover). We carried out preliminary experiments to confirm the feasibility of synchronous operation and also numerically investigated the electromagnetic phenomenon within the bulk superconductor by a developed computer program based on the finite element method.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Bayesian classification of myocardial excitation abnormality using magnetocardiogram maps for mass screening

    Yumie Ono, A. Ishiyama, N. Kasai, S. Yamada, K. On, S. Watanabe, I. Yamaguchi, T. Miyashita, K. Tsukada

    Neurology and Clinical Neurophysiology   2004  2004

     View Summary

    We propose a novel classification method based on the Bayes rule to utilize the magnetocardiogram (MCG) in noninvasive mass screening. The cardiac excitation is directly tracked by maps of the MCG field generated by myocardial excitation current through the excited wave front. To adopt the characteristics of the excited wave fronts as a parameter for the Bayes theorem, we developed a parameterization procedure that consists of a two-dimensional wavelet approximation and a cluster analysis of magnetic field maps. With the parameter determined by this procedure, the probability of a subject to belong to a disease group or to the normal group is estimated by the Bayes theorem. The subject is classified into the group of the highest probability. We applied the proposed method to ST-T period of MCG data of 6 old myocardial infarction (OMI) patients and 15 normal controls. The method showed sensitivity of 83%
    specificity, 100%
    positive predictive value, 100%
    and negative predictive value, 94% in the classification of OMI patients and normal controls. The processing time is less than 5 seconds per one subject. It suggests a possible application of the proposed method in mass screening of abnormal MCG patterns.

    PubMed

  • Development of a Low-Magnetic-Noise Nondestructive Inspection System Using a Superconducting Quantum Interference Device Cooled by a Coaxial Pulse Tube Cryocooler

    HATSUKADE Yoshimi, KASAI Naoko, TAKASHIMA Hiroshi, MARUNO Yoshio, ISHIYAMA Atsushi

    TEION KOGAKU   38 ( 12 ) 686 - 692  2003.12

     View Summary

    A small, low-magnetic-noise nondestructive inspection (NDI) system that uses a high-Tc superconducting quantum interference device (SQUID) cooled by a coaxial pulse tube cryocooler (PTC) has been developed. The key components for realizing the compact, low-noise system developed in this study, include the following: a high-Tc SQUID gradiometer, the coaxial PTC, and a SQUID-mount stage separated from the cold head of the cryocooler. The high-Tc SQUID gradiometer contributes not only to stable system operation when subjected to the environmental noise without magnetic shielding, but also a decrease in magnetic noise caused by the mechanical vibration of the SQUID, which is transmitted from the cryocooler. By using the coaxial PTC, which was constructed of non-magnetic materials, both magnetic noise and the mechanical vibration are well suppressed compared to conventional two-axial PTCs. In addition, the coaxial PTC is designed to be compact (50 mm diameter, 400 mm height, and 4 kg weight) for practical use. The SQUID-mount stage separation contributes to stable operation by reducing the transmitted vibration to the SQUID, and thermal stability at the SQUID-mount stage. The magnetic flux noise spectrum of the cryo-cooled system was measured and compared with that of a liquid-nitrogen-cooled system using the same SQUID. From the comparison, no increase in magnetic noise due to the cryocooler was observed, although the magnetic flux noise level of the cryo-cooled system was dominated by SQUID operation noise, which was rather high, (i.e., around 100 μΦ0/Hz1/2 at 100 Hz). The relation between the mechanical vibration at the SQUID and magnetic noise is discussed.

    DOI CiNii

  • Trial design of a 6.6-kV magnetic shielding type of superconducting fault current limiter and performance analysis based on a finite element method

    H Kado, M Ichikawa, H Ueda, A Ishiyama

    ELECTRICAL ENGINEERING IN JAPAN   145 ( 2 ) 50 - 57  2003.11  [Refereed]

     View Summary

    Superconducting fault current limiter (SCFCL) is expected to be a first application of high-T-C superconductors to electric power systems. We have been developing a magnetic shielding type of SCFCL. In this paper, we propose a design method for the magnetic shield SCFCL. The method is based on a newly developed computer program which can evaluate the dynamic thermal and electromagnetic behaviors of high-T-C superconducting cylinder in fault current limiter operation. As an example, the trial design of a model system, which is 6.6 kV (rms) in rated voltage, 400 A(rms) in rated current, and 12.5 kA(rms) in maximum prospective short-circuit current, is shown. (C) 2003 Wiley Periodicals, Inc.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • An optimization method for design of SMES coils using YBCO tape

    S Noguchi, H Yamashita, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   13 ( 2 ) 1856 - 1859  2003.06  [Refereed]

     View Summary

    Recently, the properties of high temperature superconducting (HTS) tapes have been in advance and HTS magnets have been constructed and demonstrated. However, the HTS tapes have thermal different characteristics compared with the low temperature superconducting (LTS) wires. Moreover, Bi2223/Ag tapes and YBCO coated conductors have the different properties about the dependence on the degree of external magnetic field. Therefore it is necessary to consider these characteristics of HTS tapes at magnet design stage. We proposed an optimal design method for superconducting coils using Bi2223/Ag tapes. And the proposed configuration is optimized by using the simulated annealing (SA), which is one of the optimization algorithms, under a lot of constraints such as B-I characteristic, storage energy, and so on. The details of the optimization method and an example of its application to SMES coils (72 NU) using YBCO coated conductors are shown.

    DOI

    Scopus

    40
    Citation
    (Scopus)
  • A new type of active-Maglev system using YBCO bulk and multiple electromagnets

    R Kamoshida, H Ueda, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   13 ( 2 ) 2157 - 2160  2003.06  [Refereed]

     View Summary

    We have been developing a new type of active-maglev system that is a transporter in the vertical direction, consisting of high-temperature bulk superconductors and multiple electromagnets piled up on the vertical axis. In a previous paper, using an active-maglev system composed of a disk-shaped YBCO bulk and five electromagnets, we have demonstrated continuous levitation and verified that its levitation height, as well as stability, call be remarkably improved by adjusting the operating current of the electromagnets individually. Electromagnetic behavior within the bulk has been also investigated numerically by a newly developed computer program based on the finite-element method adopting the Bean model. Agreement of levitation force and height between experiments and numerical analyses was good. The levitation force properties strongly depend on the field-cooling condition and the distribution and magnitude of the external magnetic field generated by the electromagnets.,We clarify electromagnetic phenomena within the bulk superconductor by the computer program developed to improve the levitation properties for applications of continuous levitation to real maglev systems.

    DOI

    Scopus

    10
    Citation
    (Scopus)
  • Characteristics of levitating X-Y transporter using HTS bulks

    T Akamatsu, H Ueda, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   13 ( 2 ) 2161 - 2164  2003.06  [Refereed]

     View Summary

    High-T-c. superconducting bulk has been used for magnetic levitation systems such as flywheel energy storage system and noncontact transport system. We have been investigating the electromagnetic behavior of high temperature superconductor (HTS) bulks to realize a X-Y (two-dimensional) magnetic levitating transporter without any fixed guides. We have investigated qualitatively the characteristics. of the lift and the restoring force of an YBCO bulk under various field-cooling conditions and permanent-magnet arrangements. In this paper, we evaluate the most suitable 4-permanent-magnet arrangement through lift and restoring force measurements and numerical analysis by the finite element method (FEM) using the current vector potential.

    DOI

    Scopus

    18
    Citation
    (Scopus)
  • Trial production and experiment of linear synchronous actuator with field-cooled HTS bulk secondary

    A Takahashi, H Ueda, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   13 ( 2 ) 2251 - 2254  2003.06  [Refereed]

     View Summary

    It is expected that HTS bulk materials can be applied to various electric devices. We have fabricated and tested a linear actuator with a single-sided primary and an HTS bulk secondary. The linear actuator was comprised of a zero-field-cooled YBCO bulk plate tor the secondary (mover) and copper windings with iron core for the primary. In this study, to improve the characteristics of the linear. actuator, we designed and fabricated a double-sided and short-secondary type of linear synchronous actuator which has a field-cooled YBCO bulk plate as a secondary (mover). The static synchronous thrust forces were measured. To evaluate the static characteristics of the linear actuator, we also numerically investigated the electromagnetic behavior within the bulk in an operational environment of the linear actuator by using a computer program based on the finite element method (FEM). The influence of the supercurrent distribution in the bulk on the thrust-angle characteristics of the model linear actuator are discussed.

    DOI

    Scopus

    13
    Citation
    (Scopus)
  • Trapped field characteristic of HTS bulk in AC external magnetic field

    H Ueda, M Itoh, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   13 ( 2 ) 2283 - 2286  2003.06  [Refereed]

     View Summary

    Although immutable trapped field is required in superconducting bulk applications as a quasipermanent magnet, the trapped field is influenced and changed by time-varying external magnetic field in a realistic operational environment of electrical devices. This means that shielding current distribution within bulk is changed by the time-varying magnetic field and the transient magnetic flux movement results in temperature rise and finally reduction of the trapped field. In this paper, we experimentally investigated the transition of trapped field while applying external AC magnetic field with various amplitude and frequency to a disk-shaped. YBCO bulk. And we also numerically investigate the relationship between characteristic of trapped-field attenuation and shielding current distribution within the bulk using a newly developed simulation Program. This program is based on the finite element method (FEM) considering the voltage-current (E-J) characteristics. It is found that the shielding current distribution is dependent on frequency of AC external field and trapped field attenuation is closely related-to the shielding current.

    DOI

    Scopus

    32
    Citation
    (Scopus)
  • New applications of high-temperature bulk superconductors

    ISHIYAMA Atsushi

      72 ( 1 ) 31 - 35  2003.01  [Refereed]  [Invited]

    DOI CiNii

  • 6.6kV級磁気遮へい型超電導限流器の試設計と有限要素法による動作特性評価

    門裕之, 市川路晴, 植田浩史, 石山敦士

    電気学会論文誌B(電力・エネルギー部門誌)   122-B ( 8 ) 944 - 950  2002.08  [Refereed]

    DOI

  • An optimal design method for SMES coils using HTS tapes

    S Noguchi, H Yamashita, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   12 ( 1 ) 1459 - 1462  2002.03

     View Summary

    This paper describes an optimal design method for SMES coils wound with high temperature superconducting (HTS) tapes (e.g., Bi2223/Ag tapes). Recently, the properties of HTS tapes have advanced and HTS magnets have been constructed and demonstrated [1]-[3]. However, the HTS tapes have thermal different characteristics compared with the low temperature superconducting (LTS) wires. Therefore, it is necessary to consider these characteristics of HTS tapes at magnet design stage. We propose an optimal design method for SMES coils using Bi2223/Ag tapes. And the proposed configuration is optimized by using the simulated annealing, (SA), which is one of the optimization algorithms, under a lot of constraints such as B-I characteristic, storage energy, and so on. The details of the optimization method and examples of its application to small SMES coils (0.5 MJ) using Bi2223/Ag tape are shown.

    DOI

    Scopus

    26
    Citation
    (Scopus)
  • A new type of active-maglev system using YBCO bulk and multiple electromagnets

    H Hayashi, H Ueda, M Tsuda, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   12 ( 1 ) 907 - 910  2002.03  [Refereed]

     View Summary

    We present a, new type of active-maglev system consisting of a disk-shaped superconducting bulk (YBCO) and multiple electromagnets. Using the active-maglev system composed of five electromagnets, we demonstrated. continuous levitation and verified that the levitation height, as well as stability, could be remarkably improved by adjusting operating current of electromagnet individually. Electromagnetic behavior within the bulk was investigated numerically by the finite element method (FEM) adopting the Bean model. Agreements of levitation force and height between experiment and analysis were good. Suitable electromagnet operation for continuous levitation in terms of consumed operating energy was also investigated. It was found in analysis that continuous levitation could be realized efficiently by adopting a three-electromagnet operation and the operating procedure is applicable to multiple-electromagnet system. Therefore, based on the assumption of constant total operating current of three electromagnets, we numerically investigated the relationship between the operating procedure and levitation force in a five-electromagnet system as a function of levitation height. Maximum allowable weight of float (superconducting bulk and load) was evaluated through the estimation of minimum levitation force during continuous levitation as a function of air gap between electromagnets.

  • Trapped field characteristics of Y-Ba-Cu-O bulk in time-varying external magnetic field

    H Shimizu, H Ueda, M Tsuda, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   12 ( 1 ) 820 - 823  2002.03  [Refereed]

     View Summary

    It is very important to clarify characteristics of trapped field in HTS bulk exposed to an external AC magnetic field in application of high-temperature superconducting bulk to motors, magnetic levitation systems, bulk magnets and so on. We have experimentally investigated the transition of trapped field while applying external AC magnetic field to a disk-shaped YBCO bulk. The observed trapped-field attenuation is different from that by flux creep, i.e., zero external field. It may be considered that the trapped-field attenuation is affected by external AC magnetic field, particularly temperature rise due to AC loss. In this paper, electromagnetic behaviors within the bulk exposed to external AC magnetic field, especially supercurrent distribution, are investigated numerically using a simulation code based on the finite element method (FEM) considering voltage-current (E-J) characteristic. We focus on the relationship between the transition of supercurrent distribution within the bulk while applying external AC magnetic field and both n-value of E-J characteristic and temperature rise by AC loss.

  • Static and dynamic characteristics in levitating X-Y transporter using HTS bulks

    Y Teranishi, H Ueda, A Tsuda, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   12 ( 1 ) 911 - 914  2002.03  [Refereed]

     View Summary

    High T-c superconducting bulk has been used for magnetic levitation systems such as flywheel energy storage system, noncontact transport system and so on. We have been investigating electromagnetic behaviors of HTS bulk to realize a X-Y (two-dimensional) magnetic levitating transporter without any fixed guides. We have investigated qualitatively the characteristics of lift and restoring force of an YBCO bulk for various field-cooling conditions and permanent-magnet arrangements. In this paper, we evaluated the most suitable conditions of air gap in field-cooling process and permanent-magnet arrangement through lift and restoring force measurements and numerical analysis by the finite element method (FEM) based on the current vector potential method. the characteristics of oscillation in the vertical direction of levitating X-Y transporter were investigate by the measurements of free and forced vibrations. The theoretical characteristics of the free and forced vibrations were compare with the experiments.

  • Trial production and experiment of linear actuator with double-sided primary and HTS bulk secondary

    S Sadakata, H Ueda, M Tsuda, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   12 ( 1 ) 824 - 827  2002.03  [Refereed]

     View Summary

    It is expected that HTS bulk materials are applied to various electric devices. In a previous work we have fabricated and tested a linear actuator with single-sided primary and HTS bulk secondary. The linear actuator was comprised of zero-field-cooled YBCO bulk for secondary (mover) and copper windings with iron core (primary). The primary was excited by a three-phase VVVF power source to provide sinusoidal traveling field. To improve the characteristics of the linear actuator, we newly designed and fabricated a linear actuator with double-sided primary and zero-field-cooled HTS bulk secondary. We measured starting thrust force and magnetic field distribution in the air gap between the bulk and the primary iron core at the stationary state. To evaluate dynamic characteristics of the linear actuator, we numerically investigated electromagnetic behavior within the bulk exposed to time-varying magnetic field using a simulation program based on the finite element method (FEM) taking the voltage-current (E-J) characteristic into consideration. Computed starting thrust force, displacement characteristic and field distribution between the bulk and the primary iron core were compared with the experimental results. Agreement between experiments and analyses was good. We also investigated the electromagnetic characteristics as a linear synchronous actuator with double-sided primary and field-cooled HTS bulk secondary.

  • Characteristics of Active-maglev System Using YBCO Bulk and Multiple Electromagnets

    H. Ueda, H. Hayashi, A. Ishiyama, M. Tsuda

    Physica C   372-376 ( PART 3 ) 1466 - 1469  2002  [Refereed]

     View Summary

    One useful feature of the active-maglev system is that levitation height is adjustable by varying operating current in electromagnets. To improve the levitation height, we have designed and constructed a new type of active-maglev system with two electromagnets instead of using a larger single electromagnet. The levitation height, as well as stability, was remarkably improved by adjusting the operating current of each electromagnet individually. Although the bulk is levitated up to high position, the lower electromagnet is continued to operate in continuous levitation using multiple electromagnets. It is waste that the lower electromagnet is continued to operate. The required energy for the electromagnet operation should be minimized. In this paper, we tried to realize continuous levitation with keeping the total operating current constant in five-electromagnet active-maglev system and investigate electromagnetic behavior within the bulk using a newly developed FEM computer program. Continuous levitation was successfully achieved under the desired operating condition. Agreements between experiment and analysis were excellent. © 2002 Published by Elsevier Science B.V.

    DOI

    Scopus

    5
    Citation
    (Scopus)
  • 遺伝的アルゴリズムとシミュレーテッド・アニーリングを組み合わせた脳内複数信号源推定法

    電気学会基礎材料共通部門誌A分冊   122 ( 1 ) 93 - 99  2002.01  [Refereed]

    DOI

  • 空間周波数解析を用いた心筋の興奮伝播解析—心磁界シミュレーションによる検討—

    電気学会基礎材料共通部門誌A分冊    2001.12  [Refereed]

    DOI

  • バルク超電導体と複数の電磁石による鉛直方向連続アクティブ磁気浮上の特性評価

    植田浩史, 林 浩幹, 石山敦士, 津田 理

    電気学会論文誌    2001.10  [Refereed]

  • Trapped field characteristics of Y-Ba-Cu-O bulk in time-varying external magnetic field

    T Ohyama, H Shimizu, M Tsuda, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   11 ( 1 ) 1988 - 1991  2001.03  [Refereed]

     View Summary

    The trapped field characteristics of disk-shaped YBCO bulk exposed to external AC magnetic field are investigated experimentally, The magnetic flux density an the top surface of the disk defined as "trapped flux" in this paper, was measured in both short and long tel ms as functions of amplitude and frequency of the AC external magnetic field. The observed trapped flux attenuation was obviously different from that of flux creep, i.e,, with no external magnetic field; this Implies that the trapped flux density within the YBCO dish is reduced by a temperature rise due to AC loss, The abrupt attenuation of trapped flux density in the first several cycles was observed at frequencies of 0.1 and 1 Hz, while not observed at 10 Hz The attenuation rate after seven minutes of applying AC magnetic field, however, became almost the same regardless of frequency. The trapped Bur attenuation in one cycle of, AC magnetic field decreases with the frequency and increases with the amplitude of AC magnetic field. These results imply that the characteristic of trapped pus is closely related to AC loss, especially the hysteresis-loss, and the AC loss depends on the frequency and the amplitude of the AC external magnetic field. at can he considered that transient electromagnetic behavior within HTS bulk, especially supercurrent distribution, is a key factor. of the relationship between the trapped flux attenuation and the AC loss.

  • Improvement of superconducting cylindrical linear induction motor

    T Kikuma, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   11 ( 1 ) 2331 - 2334  2001.03  [Refereed]

     View Summary

    We have constructed a model Superconducting Cylindrical (Tubular) Linear Induction Motor (SCLIM) to clarify the behaviors (AC loss, stability and so on) of AC superconducting windings in a realistic operational environment of electrical rotating machines. The studies of an AC superconductor's development in regard to the reduction of AC loss and the improvement of current capacity have been advanced From now on, the valuation of characteristic of AC superconducting windings in a realistic operational environment should be investigated. In the previous paper we presented the design and construction of SCLIM model system composed of AC superconducting primary windings, FRP cryostat and VVVF power supply with quench detection and protection circuit, and the results of fundamental driving experiments. In this paper, we optimize the current distribution in primary windings to enhance the thrust characteristics and the quench detection and protection system for AC superconducting machines by a numerical approach based on the developed FEM computer program. The measurements of the thrust force, the distributions of the magnetic flux density and primary current in the SCLIM model are also shown.

  • Development of an NDE method using SQUIDs for the reconstruction of defect shapes

    Y Hatsukade, N Kasai, H Takashima, R Kawai, F Kojima, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   11 ( 1 ) 1311 - 1314  2001.03  [Refereed]

     View Summary

    The widespread use of the SQUID-NDE requires the visualization of defects, We have developed a method to obtain depth information by monitoring the SQUID output while changing the frequency of the current flowing in a sample, The effectiveness of this method was verified by experiment and simulation.

  • An optimal design method for superconducting magnets using HTS tape

    S Noguchi, M Yamashita, H Yamashita, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   11 ( 1 ) 2308 - 2311  2001.03  [Refereed]

     View Summary

    This paper describes an optimal design method for superconducting magnets wound with high temperature superconducting (HTS) tapes (e.g. Bi2223/Ag tapes). Recently, the properties of HTS tapes have been in advance and HTS magnets have been constructed and demonstrated [1]-[4]. However, the HTS tapes have thermal different characteristics compared with the low temperature superconducting (LTS) wires. Therefore it is necessary to consider these characteristics of HTS tapes at magnet design stage. We propose a new configuration of the superconducting magnets using Bi2223/Ag tapes. And the proposed configuration is optimized by using the simulated annealing (SA), which is one of the optimization algorithms, under a lot of constraints such as B-I characteristic, central magnetic filed, held homogeneity and so on. The details of the optimization method and an example of its application to 12-tesla superconducting magnet using Bi2223/Ag tape are shown.

  • Characteristics of lift and restoring force in HTS bulk - Application to two-dimensional Maglev transporter

    Y Sanagawa, H Ueda, M Tsuda, A Ishiyama, S Kohayashi, S Haseyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   11 ( 1 ) 1797 - 1800  2001.03  [Refereed]

     View Summary

    One of the advantages of magnetic levitation using high-temperature superconducting (BTS) bulk is that stable levitation can be achieved without any control systems. We have been investigating the electromagnetic behaviors of HTS bulk to realize a two-dimensional magnetic levitating transporter without any aired guides, The characteristics of lift and stability are key parameters to design and optimize such a device. We measured the lift and the restoring force of a YBCO bulk, displaced by a distance in lateral direction, for various field-cooling conditions and permanent-magnet arrangements, Both lift and restoring force are closely related to the air gap in the field-cooling process, distance between the permanent magnets, number of permanent magnets, and permanent magnet arrangement, that is, external magnetic field distribution. The most suitable arrangement of permanent magnets depends on the required levitation height and the weight of the levitating part. It can be considered that the size of the levitating part and geometry are also very important to determine the optimal arrangement in the maglev device.

  • A stability criterion for cryocooler-cooled HTS coils

    A Ishiyama, H Asai

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   11 ( 1 ) 1832 - 1835  2001.03  [Refereed]

     View Summary

    The Magnet technology of a high-temperature superconductor (HTS) with a conduction cooling system by a GM cryocooler has been advanced. It is very important to understand the thermal and electromagnetic phenomena in HTS tapes for HTS coil design. We have measured the quench characteristics of HTS tapes with a conduction cooling system of a GM cryocooler and developed a computer program based on the finite element method (FEM) to investigate the thermal and electromagnetic behaviors within HTS tapes, From these experimental and analytical results, the validity of the computer program has been confirmed. In this paper, we discuss a stability criterion for cryocooler-cooled HTS coils by using the computer program. The current at which "thermal runaway" occurs, which depends on the relationship between the cooling power of the GM cryocooler and the heat generation within HTS coils, is chosen as a stability criterion. We also investigate the transient thermal and electromagnetic behavior in HTS coils.

  • Development of an NDE method using SQUIDs for the reconstruction of defect shapes

    Y Hatsukade, N Kasai, H Takashima, R Kawai, F Kojima, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   11 ( 1 ) 1311 - 1314  2001.03  [Refereed]

     View Summary

    The widespread use of the SQUID-NDE requires the visualization of defects, We have developed a method to obtain depth information by monitoring the SQUID output while changing the frequency of the current flowing in a sample, The effectiveness of this method was verified by experiment and simulation.

  • Characteristics of lift and restoring force in HTS bulk - Application to two-dimensional Maglev transporter

    Y Sanagawa, H Ueda, M Tsuda, A Ishiyama, S Kohayashi, S Haseyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   11 ( 1 ) 1797 - 1800  2001.03  [Refereed]

     View Summary

    One of the advantages of magnetic levitation using high-temperature superconducting (BTS) bulk is that stable levitation can be achieved without any control systems. We have been investigating the electromagnetic behaviors of HTS bulk to realize a two-dimensional magnetic levitating transporter without any aired guides, The characteristics of lift and stability are key parameters to design and optimize such a device. We measured the lift and the restoring force of a YBCO bulk, displaced by a distance in lateral direction, for various field-cooling conditions and permanent-magnet arrangements, Both lift and restoring force are closely related to the air gap in the field-cooling process, distance between the permanent magnets, number of permanent magnets, and permanent magnet arrangement, that is, external magnetic field distribution. The most suitable arrangement of permanent magnets depends on the required levitation height and the weight of the levitating part. It can be considered that the size of the levitating part and geometry are also very important to determine the optimal arrangement in the maglev device.

  • Trapped field characteristics of Y-Ba-Cu-O bulk in time-varying external magnetic field

    T Ohyama, H Shimizu, M Tsuda, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   11 ( 1 ) 1988 - 1991  2001.03  [Refereed]

     View Summary

    The trapped field characteristics of disk-shaped YBCO bulk exposed to external AC magnetic field are investigated experimentally, The magnetic flux density an the top surface of the disk defined as "trapped flux" in this paper, was measured in both short and long tel ms as functions of amplitude and frequency of the AC external magnetic field. The observed trapped flux attenuation was obviously different from that of flux creep, i.e,, with no external magnetic field; this Implies that the trapped flux density within the YBCO dish is reduced by a temperature rise due to AC loss, The abrupt attenuation of trapped flux density in the first several cycles was observed at frequencies of 0.1 and 1 Hz, while not observed at 10 Hz The attenuation rate after seven minutes of applying AC magnetic field, however, became almost the same regardless of frequency. The trapped Bur attenuation in one cycle of, AC magnetic field decreases with the frequency and increases with the amplitude of AC magnetic field. These results imply that the characteristic of trapped pus is closely related to AC loss, especially the hysteresis-loss, and the AC loss depends on the frequency and the amplitude of the AC external magnetic field. at can he considered that transient electromagnetic behavior within HTS bulk, especially supercurrent distribution, is a key factor. of the relationship between the trapped flux attenuation and the AC loss.

  • An optimal design method for superconducting magnets using HTS tape

    S Noguchi, M Yamashita, H Yamashita, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   11 ( 1 ) 2308 - 2311  2001.03  [Refereed]

     View Summary

    This paper describes an optimal design method for superconducting magnets wound with high temperature superconducting (HTS) tapes (e.g. Bi2223/Ag tapes). Recently, the properties of HTS tapes have been in advance and HTS magnets have been constructed and demonstrated [1]-[4]. However, the HTS tapes have thermal different characteristics compared with the low temperature superconducting (LTS) wires. Therefore it is necessary to consider these characteristics of HTS tapes at magnet design stage. We propose a new configuration of the superconducting magnets using Bi2223/Ag tapes. And the proposed configuration is optimized by using the simulated annealing (SA), which is one of the optimization algorithms, under a lot of constraints such as B-I characteristic, central magnetic filed, held homogeneity and so on. The details of the optimization method and an example of its application to 12-tesla superconducting magnet using Bi2223/Ag tape are shown.

  • Improvement of superconducting cylindrical linear induction motor

    T Kikuma, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   11 ( 1 ) 2331 - 2334  2001.03  [Refereed]

     View Summary

    We have constructed a model Superconducting Cylindrical (Tubular) Linear Induction Motor (SCLIM) to clarify the behaviors (AC loss, stability and so on) of AC superconducting windings in a realistic operational environment of electrical rotating machines. The studies of an AC superconductor's development in regard to the reduction of AC loss and the improvement of current capacity have been advanced From now on, the valuation of characteristic of AC superconducting windings in a realistic operational environment should be investigated. In the previous paper we presented the design and construction of SCLIM model system composed of AC superconducting primary windings, FRP cryostat and VVVF power supply with quench detection and protection circuit, and the results of fundamental driving experiments. In this paper, we optimize the current distribution in primary windings to enhance the thrust characteristics and the quench detection and protection system for AC superconducting machines by a numerical approach based on the developed FEM computer program. The measurements of the thrust force, the distributions of the magnetic flux density and primary current in the SCLIM model are also shown.

  • Thermal and magnetic characteristics of bulk superconductor and performance analysis of magnetic shielding type of superconducting fault current limiter

    H Ueda, A Ishiyama, H Kado, M Ichikawa

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   11 ( 1 ) 2402 - 2405  2001.03  [Refereed]

     View Summary

    Superconducting fault current limiter (SCFCL) is expected to be the first application of a high-temperature superconductor (HTS) to electric power systems. We have been developing a magnetic shielding type of SCFCL that uses a cylindrical Bi-2223 HTS bulk Short-circuit fault tests in a small SCFCL model were performed experimentally. A computer program based on the finite element method (FEM) taking the voltage-current (E-J) characteristics of the bulk material into account was developed to analyze the performance in the short-circuit fault tests and to investigate the dynamic electromagnetic behavior within a bulk superconductor. Because the E-J characteristic of HTS bulk depends on temperature and magnetic field, we investigated experimentally the E-J characteristics of a bulk superconductor in various operating temperatures and magnetic fields. The computer program considering the measured E-J characteristics simulated the electromagnetic behaviors in an SCFCL test model successfully.

  • A stability criterion for cryocooler-cooled HTS coils

    A Ishiyama, H Asai

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   11 ( 1 ) 1832 - 1835  2001.03  [Refereed]

     View Summary

    The Magnet technology of a high-temperature superconductor (HTS) with a conduction cooling system by a GM cryocooler has been advanced. It is very important to understand the thermal and electromagnetic phenomena in HTS tapes for HTS coil design. We have measured the quench characteristics of HTS tapes with a conduction cooling system of a GM cryocooler and developed a computer program based on the finite element method (FEM) to investigate the thermal and electromagnetic behaviors within HTS tapes, From these experimental and analytical results, the validity of the computer program has been confirmed. In this paper, we discuss a stability criterion for cryocooler-cooled HTS coils by using the computer program. The current at which "thermal runaway" occurs, which depends on the relationship between the cooling power of the GM cryocooler and the heat generation within HTS coils, is chosen as a stability criterion. We also investigate the transient thermal and electromagnetic behavior in HTS coils.

  • Trial production and experiments of linear actuator with HTS bulk secondary

    R Muramatsu, S Sadakata, M Tsuda, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   11 ( 1 ) 1976 - 1979  2001.03  [Refereed]

     View Summary

    To investigate characteristics of a linear actuator with high-temperature superconducting (HTS) bulk secondary, a short secondary type linear actuator has been designed and constructed. The actuator is comprised of an YBCO bulk secondary (mover) and copper windings with iron core (primary). A zero-fieid-cooled balk located at the center of the actuator plays a role of generating thrust, while four field-cooled (trapped field) bulb al e used for levitation and guidance of the secondary. We measured the starting thrust force and magnetic Weld distribution in the air gap. We developed a simulation program based on the finite element method (FEM) taking the voltage-current (E-J) characteristics of the bulk into consideration to investigate electromagnetic behaviors within the bulk exposed to a time-varying magnetic field,agreement between experiment and simulation Is good, and it validates the simulation program and the presented assumptions in the numerical approach. Using the simulation program, we investigated the dependency of n-value and critical current density of the bulk material on the magnetic flux density in the air gap and the starting thrust force. Supercurrent density within the bulk is a key factor for the magnetic flux density and the thrust force.

  • 複数の電磁石を用いたバルク超電導体の連続アクティブ磁気浮上

    津田理, 真川康弘, 林浩幹, 植田浩史, 石山敦士

    低温工学   36 ( 2 ) 68 - 78  2001.02  [Refereed]

    DOI

  • Fundamental characteristic estimation based on finite element method for magnetic shielding type superconducting fault current limiter

    A Ishiyama, J Nakatsugawa, S Noguchi, H Kado, M Ichikawa

    ELECTRICAL ENGINEERING IN JAPAN   134 ( 1 ) 17 - 27  2001.01

     View Summary

    The superconducting fault current limiter is expected to be the first application of high-Tc superconductors (HTSs) in power systems. To develop a magnetic shielding-type superconductor fault current limiter, we have carried out some fundamental experiments on the magnetic shielding characteristics of an HTS bulk cylinder. In this paper, the experimental results of magnetic flux penetration into Bi-2223 cylinders are shown. An ac magnetic field is applied to the sample by a primary winding (copper coil) excited by ac triangular- and sinusoidal-waveform currents in the frequency range from 0.1 Hz to 100 Hz. We also developed a finite element method computer program for evaluation of the dynamic electromagnetic behavior of the HTS cylinder in a time-varying external magnetic field. The results of computer simulations considering the voltage-current (E-J) characteristic are compared with experiments. Next we carried out a current-limiting test with a small limiter model, and the developed finite element method computer program successfully simulated the electromagnetic behavior in current-limiting operation. (C) 2000 Scripta Technica.

    DOI

  • Electromagnetic behavior on high-temperature superconducting bulk YBCO exposed to time-varying magnetic field

    M Tsuda, T Susa, T Ohyama, A Ishiyama, S Kohayashi, S Haseyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   10 ( 1 ) 894 - 897  2000.03  [Refereed]

     View Summary

    We present results of comprehensive study of electromagnetic behavior of high-temperature superconducting bulk YBCO exposed to time-varying magnetic field. The characteristic of trapped magnetic flux is one of the key factors in application of high-temperature superconducting bulk, such as magnetic levitation system, rotor of motor and bulk magnet. Especially, time inconstancy of trapped flux, such as flux creep, is undesirable for its application system. The relationship between time-varying external magnetic field and trapped flux is investigated experimentally using field-cooled (FC) YBCO disk. Magnetic flux density just above the disk is measured by Hall probes lined up along the disk radius. The magnetic field decay which may be independent of flux creep is observed in the experiment and is influenced significantly by frequency and amplitude of AC external magnetic field. The effect of changing rate of applied magnetic field in field-cool process on trapped flux is also investigated experimentally.

  • Electromagnetic behavior on high-temperature superconducting bulk YBCO exposed to time-varying magnetic field

    M Tsuda, T Susa, T Ohyama, A Ishiyama, S Kohayashi, S Haseyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   10 ( 1 ) 894 - 897  2000.03  [Refereed]

     View Summary

    We present results of comprehensive study of electromagnetic behavior of high-temperature superconducting bulk YBCO exposed to time-varying magnetic field. The characteristic of trapped magnetic flux is one of the key factors in application of high-temperature superconducting bulk, such as magnetic levitation system, rotor of motor and bulk magnet. Especially, time inconstancy of trapped flux, such as flux creep, is undesirable for its application system. The relationship between time-varying external magnetic field and trapped flux is investigated experimentally using field-cooled (FC) YBCO disk. Magnetic flux density just above the disk is measured by Hall probes lined up along the disk radius. The magnetic field decay which may be independent of flux creep is observed in the experiment and is influenced significantly by frequency and amplitude of AC external magnetic field. The effect of changing rate of applied magnetic field in field-cool process on trapped flux is also investigated experimentally.

  • Transport characteristics in YBCO thin film superconductors

    S Kim, Y Takahashi, K Matsumoto, T Takagi, T Machi, N Koshizuka, A Ishiyama, Hirabayashi, I

    ADVANCES IN SUPERCONDUCTIVITY XII   (]G0007[)/,619-621   619 - 621  2000  [Refereed]

     View Summary

    We studied influences of growth temperature on superconducting characteristics in YBa2Cu3O7-x (YBCO) thin films prepared by pulsed laser deposition (PLD). The films deposited at low growth temperature (below 730 degrees C) have a high c-axis orientation, good in-plane alignment and large amount of a-axis grains. With increasing growth temperature, the number of a-axis grains in the films were decreased, whereas superconducting properties were degraded due to the formation of misoriented grain boundaries. The crystal defects acting as barriers to supercurrent flow were observed by magneto-optical imaging (MOI) technique. Using this technique, we confirmed that the critical current densities of the films were limited by these defects. Dynamic magnetic flux behaviors in flux flow state were also observed by MOI system.

  • Development of linear actuator with YBCO bulk secondary

    M Tsuda, T Koike, R Muramatsu, A Ishiyama, S Kohayashi, S Haseyama

    ADVANCES IN SUPERCONDUCTIVITY XII   (]G0007[)/,818-820   818 - 820  2000  [Refereed]

     View Summary

    This paper presents the characteristic of linear actuator with high-temperature superconducting (HTS) bulk for secondary. We designed and constructed a single-sided and short-secondary type linear actuator. The actuator is comprised of YBCO bulk secondary (rotor) and copper winding (primary) with iron core. Using this model, we measured the distributions of magnetic flux density in the air gap. We developed simulation code based on a finite element method (FEM) taking the voltage-current (E-J) characteristic into consideration to investigate electromagnetic behavior within the bulk exposed to time-varying magnetic field. The computed magnetic flux density distribution is compared with the experiment. Numerical investigation of the effect of pole pitch in the primary on thrust is also shown.

  • Transport characteristics in YBCO thin film superconductors

    S Kim, Y Takahashi, K Matsumoto, T Takagi, T Machi, N Koshizuka, A Ishiyama, Hirabayashi, I

    ADVANCES IN SUPERCONDUCTIVITY XII     619 - 621  2000  [Refereed]

     View Summary

    We studied influences of growth temperature on superconducting characteristics in YBa2Cu3O7-x (YBCO) thin films prepared by pulsed laser deposition (PLD). The films deposited at low growth temperature (below 730 degrees C) have a high c-axis orientation, good in-plane alignment and large amount of a-axis grains. With increasing growth temperature, the number of a-axis grains in the films were decreased, whereas superconducting properties were degraded due to the formation of misoriented grain boundaries. The crystal defects acting as barriers to supercurrent flow were observed by magneto-optical imaging (MOI) technique. Using this technique, we confirmed that the critical current densities of the films were limited by these defects. Dynamic magnetic flux behaviors in flux flow state were also observed by MOI system.

  • Development of linear actuator with YBCO bulk secondary

    M Tsuda, T Koike, R Muramatsu, A Ishiyama, S Kohayashi, S Haseyama

    ADVANCES IN SUPERCONDUCTIVITY XII     818 - 820  2000  [Refereed]

     View Summary

    This paper presents the characteristic of linear actuator with high-temperature superconducting (HTS) bulk for secondary. We designed and constructed a single-sided and short-secondary type linear actuator. The actuator is comprised of YBCO bulk secondary (rotor) and copper winding (primary) with iron core. Using this model, we measured the distributions of magnetic flux density in the air gap. We developed simulation code based on a finite element method (FEM) taking the voltage-current (E-J) characteristic into consideration to investigate electromagnetic behavior within the bulk exposed to time-varying magnetic field. The computed magnetic flux density distribution is compared with the experiment. Numerical investigation of the effect of pole pitch in the primary on thrust is also shown.

  • バルク超電導体特性の温度・磁界依存性と磁気遮へい型超電導限流器の動作特性解析

    門裕之, 市川路晴, 植田浩史, 石山敦士

    低温工学/低温工学会   35 ( 5 ) 246 - 254  2000.01  [Refereed]

    DOI

  • radial成分をもつ信号源推定のためのMEG/EEG併用法

    石山敦士, 上杉直登, 大能祐介, 葛西直子

    電気学会論文誌(A部門誌)   119-A ( 12 ) 1451 - 1458  1999.12  [Refereed]

    DOI

  • 有限要素法による磁気遮へい型超電導限流器の基礎特性評価

    石山敦士, 中津川潤之介, 野口聡, 門裕之, 市川路晴

    電気学会論文誌(B部門誌)/電気学会   119-B ( 11 ) 1201 - 1209  1999.11  [Refereed]

    CiNii

  • Quench propagation properties in HTS pancake coil

    S Shimizu, A Ishiyama, SB Kim

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   9 ( 2 ) 1077 - 1080  1999.06  [Refereed]

     View Summary

    In this paper, we present the results of experiments and computer simulations to make clear the quench propagation properties in Bi-2223/Ag superconducting multifilament tape. We developed a computer code based on the two-dimensional finite element method (2-D FEM). Computed voltage and temperature traces during a quench agree well with the experimentally recorded voltage and temperature traces. Good agreement validates the computer code, making a useful tool in developing protection strategies for high-temperature superconducting (HTS) coils. Therefore, we simulate the quench process in a single pancake coil wound with Bi-2223/Ag superconducting multifilament tape with background magnetic filed up to 10 T at 20 K using the developed computer code. The quench propagation properties and stability in HTS coils are discussed and compare with those in low-temperature superconducting (LTS) coils.

  • Stability test results on the aluminum stabilized superconductor for the helical coils of LHD

    N Yanagi, T Satow, T Mito, S Imagawa, K Takahata, A Iwamoto, H Chikaraishi, S Yamaguchi, S Satoh, O Motojima, S Noguchi, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   9 ( 2 ) 1113 - 1116  1999.06  [Refereed]

     View Summary

    Stability tests have been carried out on short samples of the aluminum/copper stabilized composite-type superconductors developed and used for the pool-cooled helical coils of the Large Helical Device. The waveform of the longitudinal voltage initiated by resistive heaters shows a short-time rise before reaching a final value, which seems to correspond to the diffusion process of transport current into the pure aluminum stabilizer. The propagation velocity has a finite value even for the transport current being lower than the recovery current, and it differs depending on the direction with respect to the transport current.

  • Design and construction of a superconducting cylindrical linear induction motor with AC superconducting primary windings

    A Ishiyama, K Hayashi

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   9 ( 2 ) 1217 - 1220  1999.06  [Refereed]

     View Summary

    Levitated metal casting and superconducting elevators are but two of the potential applications of Superconducting Cylindrical Linear Induction Motors (SCLIMs). We are constructing a model device to clarify the behavior of AC superconducting windings in a realistic operational environment of electrical rotating machines. This paper presents design, construction, and experimental results of the model SCLIM.

  • Magnetic characteristics of a high-T-c superconducting cylinder for magnetic shielding type superconducting fault current limiter

    J Nakatsugawa, S Noguchi, A Ishiyama, H Kado, M Ichikawa

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   9 ( 2 ) 1373 - 1376  1999.06  [Refereed]

     View Summary

    The superconducting fault current limiter (SCFCL) is expected to be the first application of high-T-c superconductors (HTSs) in power systems. To develop a magnetic shielding type superconducting fault current limiter, we have carried out some fundamental experiments concerning the magnetic shielding characteristics of an HTS bulk cylinder. In this paper, the experimental results of magnetic flux penetration into a Bi(2223) cylinder are shown. AC magnetic field is applied to the sample by a primary winding (copper coil) excited by AC triangular- and sinusoidal-waveform currents in the frequency range of 0.1 Hz to 100 Hz, We also developed a Finite Element Method (FEM) computer program for evaluation of the dynamic electromagnetic behavior of the HTS cylinder in a time-varying external magnetic field. The results of computer simulations considering the voltage-current (E-J) characteristic are compared with experiments.

  • Recent technical trends of superconducting magnets in Japan, part I: Magnet data base and recent progress in magnet winding current density

    O Tsukamoto, S Torii, T Takao, N Amemiya, S Fukui, T Hoshino, A Ishiyama, A Ninomiya, H Yamaguchi, T Satow

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   9 ( 2 ) 547 - 552  1999.06  [Refereed]

     View Summary

    The committee on applied superconducting apparatuses and characteristics of superconductors, the Institute of Electrical Engineers of Japan (IEEJ) has made a data base on low temperature superconducting magnets which have been built over the last ten years in Japan. Based on the data base trends of magnet technology are investigated. In this paper (Part I), out-line of the data base is explained and based on the data base the recent trends of the magnet technology are investigated focusing on sizes and configurations of magnets, current density of magnet windings and conductor configurations. The stability and quench protection of magnets are also investigated in other paper (Part II).

  • Recent technical trends of superconducting magnets in Japan - Part II: Stability and quench characteristics

    T Takao, S Torii, N Amemiya, S Fukui, T Hoshino, A Ishiyama, A Ninomiya, H Yamaguchi, T Satow, O Tsukamoto

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   9 ( 2 ) 600 - 603  1999.06  [Refereed]

     View Summary

    The committee on applied superconducting apparatuses and characteristics of superconductors, the Institute of Electrical Engineers of japan (IEEJ) has made a data base on superconducting magnets which were built over last ten years in Japan. The outline of the data base is explained in the paper (Part I). In this paper (part II), stability and hot-spot temperature of a magnet are investigated. Minimum quench energies, minimum propagating zones, and Stekly's stability factors are calculated using the data base. Dependence of those stability parameters on the magnet scale is studied and the design trends of the stability are discussed. Hot-spot temperatures of the pool-cooled magnets at quench and energy dump process are also calculated based on the data base, and the recent trends of design rules for the quench protection are studied.

  • Transient stability of large aluminum stabilized superconductors

    S Noguchi, A Ishiyama, T Satow, N Yanagi

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   9 ( 2 ) 624 - 627  1999.06  [Refereed]

     View Summary

    Very large current composite superconductors have been considered and adopted to use in SMES coils and fusion applications, such as the Large Helical Device (LHD), These superconductors have large cross-sectional area of high purity aluminum stabilizer to improve their stability and to enhance the overall current density. Once a normal-zone is initiated in such a composite superconductor, the current transfers to the aluminum stabilizer according to the temperature distribution. The time constant of current diffusion in the stabilizer, however, is very long due to the low electrical resistivity of aluminum and the large conductor size. Therefore, an excess joule heat is generated in a small area near superconducting filaments and the temperature increases locally. In this paper, to evaluate this peculiar property we carry out some simulations with regard to quench process in the superconductor applied to the helical coil of LHD in National Institute for Fusion Science, The simulations by using a newly developed computer code are compared with the experimental results of the stability tests on the short samples of LHD conductor. Furthermore, we focus on the influence of the CuNi alloy clad adopted to the LHD conductor on the normal transition and normal-zone propagation properties.

  • Quench propagation properties in HTS pancake coil

    S Shimizu, A Ishiyama, SB Kim

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   9 ( 2 ) 1077 - 1080  1999.06  [Refereed]

     View Summary

    In this paper, we present the results of experiments and computer simulations to make clear the quench propagation properties in Bi-2223/Ag superconducting multifilament tape. We developed a computer code based on the two-dimensional finite element method (2-D FEM). Computed voltage and temperature traces during a quench agree well with the experimentally recorded voltage and temperature traces. Good agreement validates the computer code, making a useful tool in developing protection strategies for high-temperature superconducting (HTS) coils. Therefore, we simulate the quench process in a single pancake coil wound with Bi-2223/Ag superconducting multifilament tape with background magnetic filed up to 10 T at 20 K using the developed computer code. The quench propagation properties and stability in HTS coils are discussed and compare with those in low-temperature superconducting (LTS) coils.

  • Stability test results on the aluminum stabilized superconductor for the helical coils of LHD

    N Yanagi, T Satow, T Mito, S Imagawa, K Takahata, A Iwamoto, H Chikaraishi, S Yamaguchi, S Satoh, O Motojima, S Noguchi, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   9 ( 2 ) 1113 - 1116  1999.06  [Refereed]

     View Summary

    Stability tests have been carried out on short samples of the aluminum/copper stabilized composite-type superconductors developed and used for the pool-cooled helical coils of the Large Helical Device. The waveform of the longitudinal voltage initiated by resistive heaters shows a short-time rise before reaching a final value, which seems to correspond to the diffusion process of transport current into the pure aluminum stabilizer. The propagation velocity has a finite value even for the transport current being lower than the recovery current, and it differs depending on the direction with respect to the transport current.

  • Magnetic characteristics of a high-T-c superconducting cylinder for magnetic shielding type superconducting fault current limiter

    J Nakatsugawa, S Noguchi, A Ishiyama, H Kado, M Ichikawa

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   9 ( 2 ) 1373 - 1376  1999.06  [Refereed]

     View Summary

    The superconducting fault current limiter (SCFCL) is expected to be the first application of high-T-c superconductors (HTSs) in power systems. To develop a magnetic shielding type superconducting fault current limiter, we have carried out some fundamental experiments concerning the magnetic shielding characteristics of an HTS bulk cylinder. In this paper, the experimental results of magnetic flux penetration into a Bi(2223) cylinder are shown. AC magnetic field is applied to the sample by a primary winding (copper coil) excited by AC triangular- and sinusoidal-waveform currents in the frequency range of 0.1 Hz to 100 Hz, We also developed a Finite Element Method (FEM) computer program for evaluation of the dynamic electromagnetic behavior of the HTS cylinder in a time-varying external magnetic field. The results of computer simulations considering the voltage-current (E-J) characteristic are compared with experiments.

  • Design and construction of a superconducting cylindrical linear induction motor with AC superconducting primary windings

    A Ishiyama, K Hayashi

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   9 ( 2 ) 1217 - 1220  1999.06  [Refereed]

     View Summary

    Levitated metal casting and superconducting elevators are but two of the potential applications of Superconducting Cylindrical Linear Induction Motors (SCLIMs). We are constructing a model device to clarify the behavior of AC superconducting windings in a realistic operational environment of electrical rotating machines. This paper presents design, construction, and experimental results of the model SCLIM.

  • Recent technical trends of superconducting magnets in Japan - Part II: Stability and quench characteristics

    T Takao, S Torii, N Amemiya, S Fukui, T Hoshino, A Ishiyama, A Ninomiya, H Yamaguchi, T Satow, O Tsukamoto

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   9 ( 2 ) 600 - 603  1999.06  [Refereed]

     View Summary

    The committee on applied superconducting apparatuses and characteristics of superconductors, the Institute of Electrical Engineers of japan (IEEJ) has made a data base on superconducting magnets which were built over last ten years in Japan. The outline of the data base is explained in the paper (Part I). In this paper (part II), stability and hot-spot temperature of a magnet are investigated. Minimum quench energies, minimum propagating zones, and Stekly's stability factors are calculated using the data base. Dependence of those stability parameters on the magnet scale is studied and the design trends of the stability are discussed. Hot-spot temperatures of the pool-cooled magnets at quench and energy dump process are also calculated based on the data base, and the recent trends of design rules for the quench protection are studied.

  • Transient stability of large aluminum stabilized superconductors

    S Noguchi, A Ishiyama, T Satow, N Yanagi

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   9 ( 2 ) 624 - 627  1999.06  [Refereed]

     View Summary

    Very large current composite superconductors have been considered and adopted to use in SMES coils and fusion applications, such as the Large Helical Device (LHD), These superconductors have large cross-sectional area of high purity aluminum stabilizer to improve their stability and to enhance the overall current density. Once a normal-zone is initiated in such a composite superconductor, the current transfers to the aluminum stabilizer according to the temperature distribution. The time constant of current diffusion in the stabilizer, however, is very long due to the low electrical resistivity of aluminum and the large conductor size. Therefore, an excess joule heat is generated in a small area near superconducting filaments and the temperature increases locally. In this paper, to evaluate this peculiar property we carry out some simulations with regard to quench process in the superconductor applied to the helical coil of LHD in National Institute for Fusion Science, The simulations by using a newly developed computer code are compared with the experimental results of the stability tests on the short samples of LHD conductor. Furthermore, we focus on the influence of the CuNi alloy clad adopted to the LHD conductor on the normal transition and normal-zone propagation properties.

  • Development of kA-class gas-cooled HTS current lead for superconducting fault current limiter

    S. Odaka, S. B. Kim, A. Ishiyama, Y. Sato, S. Honjo, Y. Iwata, S. Shingo

    IEEE Transactions on Applied Superconductivity   9 ( 2 ) 491 - 494  1999  [Refereed]

     View Summary

    A current lead with kA capacity and small AC loss is being developed for use in superconducting current limiting devices cooled with liquid helium. A gas-cooled type current lead using Bi-based oxide superconducting bulk materials was examined to clarify the effects of the current lead geometry and the use of multiple current leads. This paper presents the results of experiments and numerical simulations based on the finite element method taking consideration of non-uniform transport current distribution among multiple current leads connected in parallel. The simulations are performed to investigate the relationship between the geometry of current leads and the amount of heat flow into a cryostat. In the simulations, the AC loss caused by both mutual and self-induced magnetic fields of multiple current leads is taken into account. The influence of AC loss, the joule heat generated by the contact resistance at joints of NbTi/CuNi multi-strand cables and the HTS bars, and the return passage for gas on the operating characteristics of the HTS current leads are evaluated. © 1999 IEEE.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • 感度解析を取り入れた高磁界・高均一超電導マグネットの最適化設計

    石山敦士, 野口聡

    電気学会論文誌/電気学会   118-B ( 10 ) 1103 - 1109  1998.10  [Refereed]

    DOI

  • Transient stability of AC multi-strand superconducting cables

    A. Ishiyama, M. Sasaki, T. Susa, S. B. Kim, M. Tsuda, H. Yumura, K. Ohmatsu, K. Sato

    Physica C: Superconductivity and its Applications   310 ( 1-4 ) 345 - 350  1998  [Refereed]

     View Summary

    AC application, it is necessary to estimate the stability of multi-strand superconducting cable. Therefore, we have been studying the transient stability of non-insulated multi-strand cable when one strand in a cable turns into the normal state locally. In the quench process, local temperature rise produced by current redistribution among strands is not desirable for stability. In a previous work, we discussed the effect of Cu matrix allocated to each strand on the transient stability and showed that the Cu matrix allocation can improve the stability of non-insulated multi-strand cable through mainly numerical simulations. In this paper, we carried out experiments on three kinds of non-insulated three-strand cables
    one consists of NbTi/CuNi strands and the others consist of NbTi/Cu/CuNi strands having different cross-sectional arrangement. These sample strands have almost the same diameter, the same matrix to superconductor ratio and the same BJ characteristics to evaluate the effect of Cu allocation quantitatively. We choose to define the transient stability in terms of the minimum quench energy (MQE) at each DC transport current. We also investigated the transient stability of sample cables when quench is initiated in two or three (all) strands simultaneously. © 1998 Elsevier Science B.V. All rights reserved.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Multi-source localization by genetic algorithm using MEG

    Takahiro Nagano, Yusuke Ohno, Naoto Uesugi, Hitoshi Ikeda, Atsushi Ishiyama, Naoko Kasai

    IEEE Transactions on Magnetics   34 ( 5 ) 2972 - 2975  1998  [Refereed]

     View Summary

    We developed a method to estimate multi-dipole sources in human brain by using Genetic Algorithm for source localization of the olfactory magnetoencephalography (MEG). Two current dipoles in each hemisphere of the brain are supposed as a source model. To investigate the ability of this method, source localization in simulation was performed by the presented method. As a result, if the noise level is restricted under 2 percent (S/N = 20), the source localization of the simulation was obtained with the error less than 1cm. © 1998 IEEE.

    DOI

    Scopus

    21
    Citation
    (Scopus)
  • Normal-zone propagation properties in Bi-2223/Ag superconducting multifilament tapes

    S. B. Kim, A. Ishiyama, H. Okada, S. Nomura

    Cryogenics   38 ( 8 ) 823 - 831  1998  [Refereed]

     View Summary

    It is expected that the normal-zone propagation of a high-temperature superconductor (HTS) is slower than that of a low-temperature superconductor (LTS) because of its large heat capacity. If the normal-zone propagates too slowly, hot spots will develop, possibly resulting in permanent conductor damage. Accordingly, there is a need to measure propagation quantitatively for designing HTS magnets. This paper describes the electromagnetic and thermal behavior of Bi-2223/Ag superconducting multifilament tapes during normal transition by conduction cooling. Some experiments were carried out under the conditions of operating temperature at 10-40 K and transport current as parameters in a zero magnetic field. Sample tapes were transited normally with a heater to initiate a quench. The voltage and temperature properties corresponding to normal transition were measured by voltage taps and thermocouples attached to the sample tapes. We also calculated longitudinal and transverse-direction normal-zone propagation velocities from the voltage and temperature traces. In the case of conduction cooling, we investigated the cooling effect due to the length of the sample tape because its cooling condition is different from the case of using a coolant - for example, liquid helium. © 1998 Published by Elsevier Science Ltd. All rights reserved.

    DOI

    Scopus

    39
    Citation
    (Scopus)
  • Optimal design method for MRI superconducting magnets with ferromagnetic shield

    S. Noguchi, A. Ishiyama

    IEEE Transactions on Magnetics   33   1904 - 1907  1997.12

     View Summary

    This paper describes an optimal design method for highly homogeneous superconducting magnet systems with ferromagnetic shield. The presented design technique is a combination of the equivalent magnetization current method for the computation of the magnetic field problem, which includes nonlinear and saturated iron, and the simulated annealing for solving the corresponding optimization problem. The equivalent magnetization current method is superior in estimating the field homogeneity of the center of the magnet systems. By using the simulated annealing, the positions of each solenoid coil are optimized as continuous design variables, while the number of turns and layers of the coil windings are treated as discrete design variables. The details of the algorithm and some examples of its application to 1.5-tesla magnet systems with three types of magnetic shielding are shown. © 1997 IEEE.

    DOI

    Scopus

    17
    Citation
    (Scopus)
  • Transient stability analysis in Bi-2223/Ag superconducting tapes

    SB Kim, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   7 ( 2 ) 203 - 206  1997.06  [Refereed]

     View Summary

    This paper presents numerical results of the finite element method(FEM) with Bi-2223/Ag superconducting multifilamentary tapes in order to estimate the transient stability, and to find out the most suitable analytical model and the behaviors at normal transition of high-Tc superconductors. We investigated the analytical model and the normal transition in the longitudinal direction using the three dimensional FEM and in the transverse direction using the two dimensional FEM and compared these with the case of low-Tc superconductors.

  • Improvement of transient stability of non-insulated AC multi-strand superconducting cables

    T Yoshino, M Tsuda, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   7 ( 2 ) 231 - 234  1997.06  [Refereed]

     View Summary

    For A.C. application, superconducting strands are bundled and twisted to make a cable with large current capacity, The quench characteristic of the cable depends on the contact thermal and electrical conductivities between strands, significantly. For improvement of the stability of non-insulated multi strand cables, it is necessary to decrease the local rise of temperature by the Joule heating in the current redistribution among strands, For this purpose, we have analytically investigated non-insulated strand cables in which the surface of each strand is covered with Cu-sheath, The transient stability of this cable is discussed analytically and experimentally.

  • Design and characteristics analysis of superconducting tubular linear induction motors

    JP Xu, S Iino, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   7 ( 2 ) 660 - 663  1997.06  [Refereed]

     View Summary

    The design and the characteristics analysis of two kinds of superconducting tubular linear induction motor are described. One has Oxide superconducting primary windings, the other has NbTi superconducting primary windings, The basic structure and design values are shown in this paper.

  • An optimal design method for high-field superconducting magnets with ferromagnetic shields

    S Noguchi, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   7 ( 2 ) 439 - 442  1997.06  [Refereed]

     View Summary

    This paper describes an optimal design method for high-field and highly homogeneous superconducting magnet systems with hybrid iron and active shielding. The presented design technique is a combination of the equivalent magnetization current method for the computation of the magnetic field problem, which includes nonlinear and saturated iron, and the simulated annealing for solving the corresponding optimization problem. The equivalent magnetization current method is superior in estimating the field homogeneity at the center of the magnet systems. By using the simulated annealing, the positions of each coil are optimized as continuous design variables, while the number of turns and layers of the coil windings are treated as discrete design variables. In this paper, the detail of the algorithm and the example of its application to 9-tesla magnet system with hybrid iron and active shield are shown.

  • Transient stability analysis in Bi-2223/Ag superconducting tapes

    SB Kim, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   7 ( 2 ) 203 - 206  1997.06  [Refereed]

     View Summary

    This paper presents numerical results of the finite element method(FEM) with Bi-2223/Ag superconducting multifilamentary tapes in order to estimate the transient stability, and to find out the most suitable analytical model and the behaviors at normal transition of high-Tc superconductors. We investigated the analytical model and the normal transition in the longitudinal direction using the three dimensional FEM and in the transverse direction using the two dimensional FEM and compared these with the case of low-Tc superconductors.

  • Improvement of transient stability of non-insulated AC multi-strand superconducting cables

    T Yoshino, M Tsuda, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   7 ( 2 ) 231 - 234  1997.06  [Refereed]

     View Summary

    For A.C. application, superconducting strands are bundled and twisted to make a cable with large current capacity, The quench characteristic of the cable depends on the contact thermal and electrical conductivities between strands, significantly. For improvement of the stability of non-insulated multi strand cables, it is necessary to decrease the local rise of temperature by the Joule heating in the current redistribution among strands, For this purpose, we have analytically investigated non-insulated strand cables in which the surface of each strand is covered with Cu-sheath, The transient stability of this cable is discussed analytically and experimentally.

  • An optimal design method for high-field superconducting magnets with ferromagnetic shields

    S Noguchi, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   7 ( 2 ) 439 - 442  1997.06  [Refereed]

     View Summary

    This paper describes an optimal design method for high-field and highly homogeneous superconducting magnet systems with hybrid iron and active shielding. The presented design technique is a combination of the equivalent magnetization current method for the computation of the magnetic field problem, which includes nonlinear and saturated iron, and the simulated annealing for solving the corresponding optimization problem. The equivalent magnetization current method is superior in estimating the field homogeneity at the center of the magnet systems. By using the simulated annealing, the positions of each coil are optimized as continuous design variables, while the number of turns and layers of the coil windings are treated as discrete design variables. In this paper, the detail of the algorithm and the example of its application to 9-tesla magnet system with hybrid iron and active shield are shown.

  • Design and characteristics analysis of superconducting tubular linear induction motors

    JP Xu, S Iino, A Ishiyama

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   7 ( 2 ) 660 - 663  1997.06  [Refereed]

     View Summary

    The design and the characteristics analysis of two kinds of superconducting tubular linear induction motor are described. One has Oxide superconducting primary windings, the other has NbTi superconducting primary windings, The basic structure and design values are shown in this paper.

  • Superconductivity Technology in the Fields of Electric Power and Energy. An Optimal Design Method for High Field and Highly Homogeneous Superconducting Magnets.

    NOGUCHI SO, ISHIYAMA ATSUSHI

    電気学会論文誌 B   116 ( 7 ) 804 - 811  1996.07  [Refereed]

    DOI J-GLOBAL

  • ビスマス系銀シース多芯テープ超伝導線材の常電導伝播特性

    低温工学/低温工学協会   31 ( 7 )  1996.07  [Refereed]

    DOI

  • Experiment and numerical analysis of normal zone propagation properties in Ag sheathed Bi-2223 superconducting tapes

    S Kim, Y Ueno, A Ishiyama, H Okada, S Nomura, H Maeda

    IEEE TRANSACTIONS ON MAGNETICS   32 ( 4 ) 2822 - 2825  1996.07  [Refereed]

     View Summary

    We measured operating temperature dependence of normal zone propagation velocity in longitudinal direction and thermal property with regard to Ag sheathed Bi-2223 superconducting single core and multifilamentary tapes, Each experiment, with the test sample cooled by a cryocooler, covers the operating temperature range 10-40K and It/Ic range 0.4 similar to 0.9 (where It is the transport current and Ic is the critical current in each operating temperature, Top). And, we also carried out numerical analysis by a three-dimensional finite element method in order to make dear the mechanism of normal zone propagation in high-temperature superconducting (HTS) conductors.

  • An optimal design method for highly homogeneous and high-field superconducting magnets

    S Noguchi, A Ishiyama

    IEEE TRANSACTIONS ON MAGNETICS   32 ( 4 ) 2655 - 2658  1996.07  [Refereed]

     View Summary

    Highly homogeneous and high-field superconducting magnets are difficult to be designed for its optimal configuration, which has the minimum winding volume. In this paper, we proposed an optimal design method, utilizing a modified Genetic algorithm, which is newly developed, to realize the minimum winding volume design for multi-section superconducting magnets. The detail of the algorithm and two examples of its application to three-section superconducting magnets are shown.

  • An optimal design method for highly homogeneous and high-field superconducting magnets

    S Noguchi, A Ishiyama

    IEEE TRANSACTIONS ON MAGNETICS   32 ( 4 ) 2655 - 2658  1996.07  [Refereed]

     View Summary

    Highly homogeneous and high-field superconducting magnets are difficult to be designed for its optimal configuration, which has the minimum winding volume. In this paper, we proposed an optimal design method, utilizing a modified Genetic algorithm, which is newly developed, to realize the minimum winding volume design for multi-section superconducting magnets. The detail of the algorithm and two examples of its application to three-section superconducting magnets are shown.

  • Stability of non-insulated AC multi-strand superconducting cables

    M Tsuda, N Toyoda, M Matsui, A Ishiyama

    IEEE TRANSACTIONS ON MAGNETICS   32 ( 4 ) 2854 - 2857  1996.07  [Refereed]

     View Summary

    For AC application, superconducting strands are bundled and twisted to make a cable with targe current capacity, The quench characteristic of the cable depends on the contact thermal and the contact electrical conductivities between strands, significantly, Also, the inter-strand contact resistance in the case of non-insulated cable and the material of the matrix of each strand have influence on the quench characteristics. In this paper, the thermal and the electromagnetic behaviors of non-insulated three-strand cable against local disturbances in one strand of multi-strand cables, taking the influence of inter-strand contact resistance and its joule heating, and the current redistribution among strands into account, are investigated, Particularly, the influence of the matrix material of cables on quench process is analytically investigated, and the results which show the influence of the joule heating by the contact conductance after local normal transition in one strand on quench process of whole cable is determined experimentally.

  • Experiment and numerical analysis of normal zone propagation properties in Ag sheathed Bi-2223 superconducting tapes

    S Kim, Y Ueno, A Ishiyama, H Okada, S Nomura, H Maeda

    IEEE TRANSACTIONS ON MAGNETICS   32 ( 4 ) 2822 - 2825  1996.07  [Refereed]

     View Summary

    We measured operating temperature dependence of normal zone propagation velocity in longitudinal direction and thermal property with regard to Ag sheathed Bi-2223 superconducting single core and multifilamentary tapes, Each experiment, with the test sample cooled by a cryocooler, covers the operating temperature range 10-40K and It/Ic range 0.4 similar to 0.9 (where It is the transport current and Ic is the critical current in each operating temperature, Top). And, we also carried out numerical analysis by a three-dimensional finite element method in order to make dear the mechanism of normal zone propagation in high-temperature superconducting (HTS) conductors.

  • 脳磁界計測における体積電流の影響-半球ファントムモデルによる実験と解析

    電気学会論文誌C/電気学会   116 ( 2 )  1996.02  [Refereed]

    DOI

  • An optimal design method for high field superconducting magnets

    S Noguchi, A Ishiyama

    PHYSICA B   216 ( 3-4 ) 212 - 214  1996.01  [Refereed]

     View Summary

    It is important for superconducting utilization, such as MRI, that superconducting magnets generate a highly homogeneous magnetic field. In order to enhance the field homogeneity, some notches are placed outside of a solenoid. The optimal design of notched solenoid arrangement becomes a problem which has both continuous and discrete design variables. In this paper, we propose an optimal design method utilizing a modified simulated annealing algorithm to realize the minimum winding volume design for notched multi-section superconducting magnets.

  • INFLUENCE OF CURRENT DISTRIBUTION ON QUENCH PROCESS IN NON-INSULATED AC MULTISTRAND SUPERCONDUCTING CABLES

    M TSUDA, K OKAZAKI, H HASHIZUME, A ISHIYAMA

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   5 ( 2 ) 596 - 599  1995.06  [Refereed]

     View Summary

    In AC multi-strand superconducting cables, AC quench current is much less than that of DC. This AC quench current degradation is caused by AC loss, mechanical damage by cabling, non-uniform current distribution among strands due to self and mutual inductances between strands, and different electrical resistivity at the joint between superconducting strands and current lead. In this paper, the current distribution and the thermal behavior of non-insulated 7- and (6+1)- strand cables applying AC transport current are analyzed and the influence of contact electrical resistivity on the current redistribution and the thermal diffusion in quench process are investigated.

  • Current Distribution Analysis in Superconducting Non-Insulated Strand Cable for AC Use

    TSUDA Makoto, ISHIYAMA Atsushi

    TEION KOGAKU   30 ( 1 ) 9 - 19  1995.01

     View Summary

    For AC application, a number of superconducting strands are twisted to make a cable with a large current capacity. However, it has been observed in such cables that the AC quench current is much less than that of DC. This AC quench current degradation is caused by mechanical damage, localized current distribution due to non-uniform self and mutual inductance between strands and due to irregular contact electrical resistivity at the joint between superconducting strands and current leads. In non-insulated 7-strand cable, we investigated the current distribution near the joint between each strand and current leads affected by contact electrical resistivity in stationary state applying AC transport current. Then, we calculated current distribution in non-insulated 7-and (6+1)-strand cables applying AC transport current to investigate the influence of contact electrical resistivity on current redistribution in the quench process. (Initial quench occurs in one strand and the current in the strand are redistributed to the other strands.) In these analysis we adopt distributed constant circuit to solve the current distrbution. From these analytical results, the characteristics of current distribution in non-insulated 7-and (6+1)-strand cables are discussed.

    DOI CiNii

  • Permissible Disturbance Energies in Filled and UnFilled High-Performance Superconducting Magnets

    ISHIYAMA A.

    IEEE Trans. Magnetics   30 ( 4 ) 2483 - 2483  1994

    DOI CiNii

    Scopus

    5
    Citation
    (Scopus)
  • Numerical Technique for Electromagnetic Field Computation. II. Boundary Element Method.:II. Boundary Element Method

    ONUKI Takashi, ISHIYAMA Atsushi

    TEION KOGAKU   27 ( 4 ) 307 - 314  1992

     View Summary

    The finite element method (FEM) is one of the most versatile methods of numerically analyzing physical phenomena described by partial differential equation. It is suitable to the analysis of such a complicated region which includes non-linear materials. It has some disadvantages, however, in dealing with the field extending infinitely. The phenomena in the electromagnetic field intrinsically spread over the infinite space. We sometimes have to consider the infinite region rigorously, e.g. in the magnetic stray field of superconducting magnets. The boundary element method (BEM) is useful to analyze very large linear fields. It reduces the domain problem to the boundary problem and is particularly suitable for analyzing the infinite space. Furthermore, the required potentials and those derivatives inside the domain are calculated by using theoretical expressions. Owing to these features, the boundary element method is especially useful for the analysis of electromagnetic phenomena. Taking account of advantages in both the finite element and the boundary element methods, the hybrid utilization of both methods (the hybrid FE-BE method) has been proposed. In this review, the recent development and several analytical results of the three-dimensional boundary element method and the hybrid FE-BE method are described.

    DOI CiNii

  • An optimal design technique for mri superconducting magnets usisg mathematical programming method

    A. Ishiyama, T. Yokoi, S. Takamori, T. Onuki

    IEEE Transactions on Magnetics   24 ( 2 ) 922 - 925  1988.03  [Refereed]

     View Summary

    This paper describes an optimal design of a highly homogeneous superconducting coil system for magnetic Resonance Imaging (MRI). The presented optimal design technique is based on a combination of a numerical Method for analysis of the magnetic field distribution and a mathematical programning method for solving the corresponding optimization problem. In this paper, the coil current density, the croos-sectional shape of coil, and the configuration of coil are optimizer so that a highly homogeneous magnetic field is realized. © 1988 IEEE

    DOI

    Scopus

    18
    Citation
    (Scopus)
  • Optimal design of superconducting magnets for whole-body nmr imaging

    A. Ishiyama, T. Yokoi, S. Takamori, T. Onuki

    IEEE Transactions on Magnetics   23 ( 2 ) 603 - 606  1987.03  [Refereed]

     View Summary

    A new optimal design technique of magnetic field systems, which utilizes a coupling procedure of the hybrid finite element-boundary element method (HFB method) and the mathematical programming, is proposed. This technique is applied to the design of the high homogeneous field superconducting magnet system with the environmental shield for whole-body NMR imaging. Results of the optimal design for three 1.0-teslamagnet systems with different types of shields (an iron shield, a shield magnet, and a combination of the iron shield and the shield magnet) are shown. © 1987 IEEE.

    DOI

    Scopus

    6
    Citation
    (Scopus)

▼display all

Books and Other Publications

  • 超電導エネルギー工学

    仁田旦三編著, 石山敦士ほか

    オーム社  2006.08 ISBN: 427420281X

  • フィニッシュ電験三種—機械③—

    小貫天編修, 石山敦士

    オーム社  1996.06

  • フィニッシュ電験三種 機械 3

    オーム社  1996.03

Presentations

  • Reduction Method of screening current-induced magnetic field considering charging delay in No-Insulated REBCO coil system

    小久保早希, 村上将吾, 石山敦士, 植田浩史, 野口聡

    電気学会研究会資料(Web) 

    Presentation date: 2021

    Event date:
    2021
     
     
  • A consideration of coil technology that takes advantage of the superior properties of REBCO coated conductor

    石山敦士, 野口聡, 植田浩史, 渡部智則, 長屋重夫, 福田光宏

    電気学会研究会資料(Web) 

    Presentation date: 2021

    Event date:
    2021
     
     
  • Development of REBCO coil system for Skeleton Cyclotron

    石山敦士, 野口聡, 植田浩史, 渡部智則, 長屋重夫, 福田光宏

    電気学会研究会資料(Web) 

    Presentation date: 2021

    Event date:
    2021
     
     
  • Numerical evaluation of screening current-induced magnetic field considering variable output energy in HTS coil system for Skelton Cyclotron

    日比祐太, 白井航大, 緒方隆充, 石山敦士, 植田浩史, 野口聡, 渡部智則, 長屋重夫, 福田光宏

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2021

    Event date:
    2021
     
     
  • Examination on reduction of screening current-induced magnetic field in scribed REBCO coil system for HTS coil system of Skelton Cyclotron

    糸日谷浩平, 白井航大, 石山敦士, 植田浩史, 野口聡, 渡部智則, 長屋重夫, 福田光宏

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2021

    Event date:
    2021
     
     
  • Screening current-induced magnetic field analysis considering charging delay in No-Insulated REBCO high-temperature superconducting coil system

    小久保早希, 上田聡美, 村上将吾, 石山敦士, 植田浩史, 野口総

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2021

    Event date:
    2021
     
     
  • Numerical evaluation on Reinforced Structure for Noncircular No-Insulation REBCO coil

    三宅雄大, 仲井悠貴, 井上良太, KIM Seokbeom, 植田浩史, 野口聡, 渡部智則, 長屋重夫, 福田光宏, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 2020

    Event date:
    2020
     
     
  • Proposal of exciting current waveform for improving magnetic field accuracy in no-insulation REBCO coil

    村上将吾, 上田聡美, 石山敦士, 植田浩史, 野口聡

    低温工学・超電導学会講演概要集 

    Presentation date: 2020

    Event date:
    2020
     
     
  • Study on Reinforcement Structure of Non-Circular High Temperature Superconducting Coil for Cyclotron Application

    仲井悠貴, 三宅雄大, KIM SeokBeom, 植田浩史, 野口聡, 渡部智則, 長屋重夫, 福田光宏, 石山敦士

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM) 

    Presentation date: 2020

    Event date:
    2020
     
     
  • Numerical evaluation of screening current-induced magnetic field considering variable output energy in HTS coil system for Skelton Cyclotron

    白井航大, 緒方隆充, 石山敦士, 植田浩史, 野口聡, 渡部智則, 長屋重夫, 福田光宏

    低温工学・超電導学会講演概要集 

    Presentation date: 2020

    Event date:
    2020
     
     
  • Study on Reinforcement Structure against Thermal Stress in Non Circular Coil for Cyclotron Applications

    三宅雄大, 仲井悠貴, KIM SeokBeom, 植田浩史, 野口聡, 渡部智則, 長屋重夫, 福田光宏, 石山敦士

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM) 

    Presentation date: 2020

    Event date:
    2020
     
     
  • Numerical Evaluation of the excitation characteristics of No-Insulation REBCO Coil systems

    村上将吾, 稲垣善太, 上田聡美, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2020

    Event date:
    2020
     
     
  • Examination of reduction method of screening-current-induced magnetic field in HTS coil system of Skeleton Cyclotron

    白井航大, 緒方隆充, 稲垣善太, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2020

    Event date:
    2020
     
     
  • 核医学治療用高温超電導スケルトン・サイクロトロンの開発(1)―REBCOコイルシステムの開発課題―

    石山敦士, 植田浩史, 野口聡, 渡部智則, 長屋重夫, 吉田潤, 福田光宏, 東達也

    低温工学・超電導学会講演概要集 

    Presentation date: 2019.05

    Event date:
    2019.05
     
     
  • 銅メッキを施した細線化REBCO線材で巻線された超電導コイルの遮蔽電流磁場低減法:電流制御法適用時の不整磁場低減効果

    上田聡美, 稲垣善太, 石山敦士, 植田浩史, 野口聡

    低温工学・超電導学会講演概要集 

    Presentation date: 2019.05

    Event date:
    2019.05
     
     
  • 銅メッキを施した細線化REBCO線材で巻線された超電導コイルの遮蔽電流磁場低減法:電流制御法適用時の挙動解析

    石崎比奈子, 上田聡美, 稲垣善太, 石山敦士, 植田浩史, 野口聡

    低温工学・超電導学会講演概要集 

    Presentation date: 2019.05

    Event date:
    2019.05
     
     
  • 核医学治療用高温超電導スケルトン・サイクロトロンの開発(2)―実証用高温超電導小型マルチコイルシステムの設計―

    野口聡, 植田浩史, 粟津佑太, KIM SeokBeom, 渡部智則, 長屋重夫, 吉田潤, 福田光宏, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 2019.05

    Event date:
    2019.05
     
     
  • 核医学治療用高温超電導スケルトン・サイクロトロンの開発(4)―実証用高温超電導小型マルチコイルシステムの機械特性解析―

    粟津佑太, KIM SeokBeom, 植田浩史, 野口聡, 渡部智則, 長屋重夫, 吉田潤, 福田光宏, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 2019.05

    Event date:
    2019.05
     
     
  • MRI用REBCOコイルシステムにおける遮蔽電流に起因する不整磁場の低減法:電流制御波形の最適化について

    緒方隆充, 稲垣善太, 石山敦士, 植田浩史, 野口聡

    低温工学・超電導学会講演概要集 

    Presentation date: 2019.05

    Event date:
    2019.05
     
     
  • 核医学治療用高温超電導スケルトン・サイクロトロンの開発(3)―実証用高温超電導小型マルチコイルシステムの遮蔽電流解析―

    植田浩史, 粟津佑太, KIM SeokBeom, 野口聡, 渡部智則, 長屋重夫, 吉田潤, 福田光宏, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 2019.05

    Event date:
    2019.05
     
     
  • 特性劣化部分を有する無絶縁REBCOコイルの特性評価

    浜中麻衣, 市川哲理, 柿本雄太, 尾下遥, 金原徹郎, 石山敦士, 野口聡

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2019.03

    Event date:
    2019.03
     
     
  • MRI用REBCOコイルシステムにおける遮蔽電流に起因する不整磁場の低減法(その2):細線化と電流制御の併用法の最適化

    緒方隆充, 稲垣善太, 伊東慶太, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2019.03

    Event date:
    2019.03
     
     
  • MRI用REBCOコイルシステムにおける遮蔽電流に起因する不整磁場の低減法(その3):ヒステリシスを利用したオーバーシュート法

    石崎比奈子, 稲垣善太, 伊東慶太, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2019.03

    Event date:
    2019.03
     
     
  • MRI用REBCOコイルシステムにおける遮蔽電流による不正磁場の低減法(その1):細線化と電流制御併用法の効果

    上田聡美, 伊東慶太, 稲垣善太, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2019.03

    Event date:
    2019.03
     
     
  • サイクロトロン用高温超電導マグネットの巻線精度が発生磁場に及ぼす影響

    三宅雄大, 粟津佑太, KIM SeokBeom, 植田浩史, 野口聡, 渡部智則, 長屋重夫, 吉田潤, 福田光宏, 石山敦士

    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM) 

    Presentation date: 2019

    Event date:
    2019
     
     
  • ヒステリシスを利用したオーバーシュート法による遮蔽電流不整磁場の低減法:9.4T級ヒト全身用MRIコイルを対象として

    稲垣善太, 伊東慶太, 石山敦士, 植田浩史, 野口聡

    低温工学・超電導学会講演概要集 

    Presentation date: 2018.11

    Event date:
    2018.11
     
     
  • 無絶縁REBCOマグネットのターン間接触抵抗の測定方法

    野口聡, 野口聡, 立田貴裕, 植田浩史, KIM Seokbeom, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 2018.11

    Event date:
    2018.11
     
     
  • 欠陥のあるREBCO線材で巻線した無絶縁パンケーキコイルの電磁的・熱的特性解析・評価

    石山敦士, 市川哲理, 尾下遥, 野口聡

    低温工学・超電導学会講演概要集 

    Presentation date: 2018.11

    Event date:
    2018.11
     
     
  • 次世代医療用スケルトンサイクロトロンに用いる高温超電導コイルシステムの電磁力解析

    粟津佑太, KIM SeokBeom, 植田浩史, 野口聡, 渡部智則, 長屋重夫, 吉田潤, 福田光宏, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 2018.11

    Event date:
    2018.11
     
     
  • Multi‐Stacked無絶縁REBCOパンケーキコイルシステムの電磁的特性の評価

    尾下遥, 市川哲理, 柿本雄太, 金原徹郎, 石山敦士, 野口聡, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2018.11

    Event date:
    2018.11
     
     
  • 高強度小型多機能スケルトンサイクロトロンの開発―遮蔽電流磁場解析―

    粟津佑太, KIM SeokBeom, 植田浩史, 野口聡, 石山敦士, 渡部智則, 長屋重夫, 吉田潤, 鶴留武尚, 高橋伸明, 三上行雄, 福田光宏

    低温工学・超電導学会講演概要集 

    Presentation date: 2018.05

    Event date:
    2018.05
     
     
  • 高強度小型多機能スケルトンサイクロトロンの開発―超電導コイル設計―

    野口聡, 植田浩史, 石山敦士, 渡部智則, 長屋重夫, 吉田潤, 鶴留武尚, 高橋伸明, 三上行雄, 福田光宏

    低温工学・超電導学会講演概要集 

    Presentation date: 2018.05

    Event date:
    2018.05
     
     
  • REBCOコイルにおける部分的細線化による遮蔽電流磁場低減効果:9.4‐T級ヒト全身用MRIコイルを対象として

    稲垣善太, 小曽根裕一, 伊東慶太, 石山敦士, 植田浩史, 野口聡

    低温工学・超電導学会講演概要集 

    Presentation date: 2018.05

    Event date:
    2018.05
     
     
  • 高強度小型多機能スケルトンサイクロトロンの開発―超電導コイルシステム要求仕様―

    石山敦士, 植田浩史, 野口聡, 渡部智則, 長屋重夫, 吉田潤, 鶴留武尚, 高橋伸明, 三上行雄, 福田光宏

    低温工学・超電導学会講演概要集 

    Presentation date: 2018.05

    Event date:
    2018.05
     
     
  • 高強度小型多機能スケルトンサイクロトロンの開発―全体概要―

    福田光宏, 石山敦士, 植田浩史, 野口聡, 渡部智則, 長屋重夫, 吉田潤, 鶴留武尚, 高橋伸明, 三上行雄

    低温工学・超電導学会講演概要集 

    Presentation date: 2018.05

    Event date:
    2018.05
     
     
  • 9.4T‐MRIにおけるREBCO線材の細線化による遮蔽電流磁場への影響の解析

    稲垣善太, 伊東慶太, 小曽根裕一, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2018.03

    Event date:
    2018.03
     
     
  • サイクロトロン用高温超電導マグネットの遮蔽電流磁場評価

    粟津佑太, KIM Seok Beom, 植田浩史, 野口聡, 石山敦士, 渡部智則, 長屋重夫, 吉田潤, 鶴留武尚, 高橋伸明, 三上行雄, 福田光宏

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2018.03

    Event date:
    2018.03
     
     
  • Research and Development of a High-field Coil System:– Development of a high-temperature superconducting magnet for ultrahigh-field MRI –

    MIYAZAKI Hiroshi, FUKUYAMA Hidenao, IWAI Sadanori, TOSAKA Taizo, NOMURA Shunji, KURUSU Tsutomu, UEDA Hiroshi, NOGUCHI So, ISHIYAMA Atsushi, URAYAMA Shinichi  [Invited]

    TEION KOGAKU (Journal of Cryogenics and Superconductivity Society of Japan)  CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN

    Presentation date: 2017.07

    Event date:
    2017.07
     
     

     View Summary

    <p>A project for developing of RE1Ba2Cu3O7-&delta; (REBCO) magnets to be utilized in ultrahigh-field magnetic resonance imaging (MRI) was started in 2013. Our final targets are 9.4 T MRI systems for whole-body and brain imaging. In this project, two different development approaches towards the final target were planned. One is a small REBCO coil that can generate 10 Tclass magnetic fields, which is the same level as the target magnetic field. The other is a conduction-cooled 1.5 T REBCO MRI magnet that has a room-temperature bore of 396 mm, which is as large as those of mid-sized model magnets. These results were reflected in the design of a conduction-cooled 9.4 T REBCO magnet for whole-body MRI systems.</p>

  • REBCOパンケーキコイルの遮蔽電流磁場簡易計算法

    宮尾亮介, 植田浩史, 石山敦士, HAHN Seungyoung, 野口聡

    低温工学・超電導学会講演概要集 

    Presentation date: 2017.05

    Event date:
    2017.05
     
     
  • 超電導線接続箇所を有する無絶縁REBCOパンケーキコイルの熱的安定性評価

    柿本雄太, ZHENG Qiyi, 矢代聡佳, 市川哲理, 石山敦士, 野口聡, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2017.05

    Event date:
    2017.05
     
     
  • ML‐MI REBCOパンケーキコイルにおける層間電気抵抗の調整実験

    市川哲理, 矢代聡佳, ZHENG Qiyi, 柿本雄太, 石山敦士, 野口聡

    低温工学・超電導学会講演概要集 

    Presentation date: 2017.05

    Event date:
    2017.05
     
     
  • 9.4T級ヒト全身用MRI用コイルにおける遮蔽電流による不整磁場の解析・評価

    伊東慶太, 石山敦士, 植田浩史, 野口聡, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集 

    Presentation date: 2017.05

    Event date:
    2017.05
     
     
  • 銅メッキ付き多芯REBCO線材における遮蔽電流による不整磁場の低減効果

    武藤優真, 石山敦士, 小泉智暉, 植田浩史, KIM Seok Beom, 野口聡

    低温工学・超電導学会講演概要集 

    Presentation date: 2017.05

    Event date:
    2017.05
     
     
  • 複数の超電導線接続箇所を有する無絶縁REBCOコイルの熱的安定性評価

    柿本雄太, 勝俣一輝, ZHENG Qiyi, 矢代聡佳, WANG Tao, 石山敦士, 野口聡, 長屋重夫, 渡部智則

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2017.03

    Event date:
    2017.03
     
     
  • 9.4T級ヒト全身用MRI用コイルにおける遮蔽電流による不整磁場の解析

    伊東慶太, 中園浩平, 石山敦士, 植田浩史, 野口聡, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努, 浦山慎一, 福山秀直

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2017.03

    Event date:
    2017.03
     
     
  • 無絶縁REBCOパンケーキコイルにおける層間接触電気抵抗の調整に関する検討

    市川哲理, 勝俣一輝, 矢代聡佳, ZHENG Qiyi, 石山敦士, 野口聡, 渡部智則, 長屋重夫

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2017.03

    Event date:
    2017.03
     
     
  • REBCOコイルにおける細線化処理による遮蔽電流不整磁場低減効果の解析:9.4T級ヒト全身用MRIコイルを対象として

    伊東慶太, 石山敦士, 植田浩史, 野口聡

    低温工学・超電導学会講演概要集 

    Presentation date: 2017

    Event date:
    2017
     
     
  • 銅メッキ付き多芯REBCOテープ線材で巻線された高温超電導コイルの遮蔽電流評価実験と解析

    植田浩史, 石山敦士, 柳澤吉紀, 前田秀明

    低温工学・超電導学会講演概要集 

    Presentation date: 2017

    Event date:
    2017
     
     
  • REBCO線材における細線化による遮蔽電流に起因する不整磁場の低減効果

    武藤優真, 中園浩平, 小曽根裕一, 石山敦士, 植田浩史

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2017

    Event date:
    2017
     
     
  • HTS-SQUIDを用いたラット心磁図計測の有用性の検討 (超伝導エレクトロニクス)

    日向野 将, 安田 昌太郎, 石山 敦士, 小野 弓絵, 廿日出 好

    電子情報通信学会技術研究報告 = IEICE technical report : 信学技報  電子情報通信学会

    Presentation date: 2016.08

    Event date:
    2016.08
     
     
  • SQUIDによるラット心磁図への統計解析を用いた肺動脈性肺高血圧症検出法 (超伝導エレクトロニクス)

    安田 昌太郎, 日向野 将, 小野 弓絵, 梶村 いちげ, 南沢 享, 石山 敦士

    電子情報通信学会技術研究報告 = IEICE technical report : 信学技報  電子情報通信学会

    Presentation date: 2016.08

    Event date:
    2016.08
     
     
  • Development of an HTS magnet for ultra-high field MRI

    宮崎 寛史, 岩井 貞憲, 戸坂 泰造, 野村 俊自, 来栖 努, 植田 浩史, 野口 聡, 石山 敦士, 浦山 慎一, 福山 秀直

    電気学会研究会資料. MC  電気学会

    Presentation date: 2016.06

    Event date:
    2016.06
     
     
  • Reduction technique of Irregular Magnetic Field Distribution Generated by Screening Current in REBCO Multiple Coils

    小曽根 裕一, 中園 浩平, 王 韜, 石山 敦士, 植田 浩史, 野口 聡, 宮崎 寛史, 戸坂 泰造, 野村 俊自, 来栖 努

    電気学会研究会資料. MC  電気学会

    Presentation date: 2016.06

    Event date:
    2016.06
     
     
  • 高磁場MRI用高温超電導磁石の開発(16年春)―伝導冷却1.5T‐MRI磁石の試験結果―

    宮崎寛史, 岩井貞憲, 宇都達郎, 大谷安見, 戸坂泰造, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 植田浩史, 野口聡, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2016.05

    Event date:
    2016.05
     
     
  • 高磁場MRI用高温超電導磁石の開発(16年春)―REBCOマルチコイルにおける遮蔽電流による不整磁場の低減法―

    小曽根裕一, WANG Tao, 石山敦士, 植田浩史, 野口聡, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集 

    Presentation date: 2016.05

    Event date:
    2016.05
     
     
  • (50T・500A/mm2・5GPa)‐REBCO超電導コイルシステムの開発

    石山敦士, 我妻洸, 齋藤隆, 野口聡, 植田浩史, KIM SeokBeom, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2016.05

    Event date:
    2016.05
     
     
  • 高磁場MRI用高温超電導磁石の開発(16年春)―全体概要―

    戸坂泰造, 宮崎寛史, 岩井貞憲, 宇都達郎, 大谷安見, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 植田浩史, 野口聡, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2016.05

    Event date:
    2016.05
     
     
  • 高磁場MRI用高温超電導磁石の開発(16年春)―9.4T高温超電導MRI磁石設計―

    宮崎寛史, 岩井貞憲, 宇都達郎, 大谷安見, 戸坂泰造, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 植田浩史, 野口聡, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2016.05

    Event date:
    2016.05
     
     
  • PEECモデルによる無絶縁REBCOダブルパンケーキコイルにおける局所常電導転移発生時の電流分布解析

    宮尾亮介, 野口聡, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 2016.05

    Event date:
    2016.05
     
     
  • 高磁場MRI用高温超電導磁石の開発(16年春)―工業製品化を前提とするMRI用REBCOコイルシステムの開発―

    石山敦士, 植田浩史, 植田浩史, 野口聡, 野口聡, 浦山慎一, 福山秀直, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集 

    Presentation date: 2016.05

    Event date:
    2016.05
     
     
  • 高磁場MRI用高温超電導磁石の開発(‘16年春)―9.4Tヒト全身用MRIコイルの最適化設計と不整磁場評価―

    植田浩史, 植田浩史, 野口聡, 野口聡, 石山敦士, 岩井貞憲, 戸坂泰造, 宮崎寛史, 野村俊自, 来栖努, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2016.05

    Event date:
    2016.05
     
     
  • PEECモデルを用いた無絶縁REBCOダブルパンケーキコイルにおける局所常電導転移発生時に関する数値シミュレーション

    宮尾亮介, 門馬克敏, 野口聡, 石山敦士

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2016.03

    Event date:
    2016.03
     
     
  • 9.4Tヒト全身用MRIコイルにおける遮蔽電流による不整磁場と磁場均一度の評価

    中園浩平, 松見絢子, WANG Tao, 石山敦士, 植田浩史, 野口聡, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努, 浦山慎一, 福山秀直

    電気学会超電導機器研究会資料 

    Presentation date: 2016.02

    Event date:
    2016.02
     
     
  • 10T級MRI用高温超電導磁石の開発-REBCOマルチコイルにおける遮蔽電流による不整磁場の評価試験と解析-

    小曽根裕一, 持田歩, WANG Tao, 石山敦士, 植田浩史, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2016

    Event date:
    2016
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(15年秋)9.4Tヒト全身用MRIコイルにおける遮蔽電流による不整磁場と磁場均一度の評価

    松見絢子, WANG Tao, 石山敦士, 植田浩史, 野口聡, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集 

    Presentation date: 2015.12

    Event date:
    2015.12
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(15年秋)―進捗概要―

    戸坂泰造, 宮崎寛史, 岩井貞憲, 宇都達郎, 大谷安見, 高橋政彦, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 植田浩史, 野口聡, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2015.12

    Event date:
    2015.12
     
     
  • 2次元有限要素法を用いた無絶縁超電導コイルのターン間電流経路解析

    川口浩平, 門馬克敏, 野口聡, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 2015.12

    Event date:
    2015.12
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(15年秋)―極小口径10Tコイルの開発―

    岩井貞憲, 宮崎寛史, 大谷安見, 宇都達郎, 戸坂泰造, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 植田浩史, 野口聡, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2015.12

    Event date:
    2015.12
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(15年秋)―伝導冷却1.5T‐MRI磁石の開発―

    宮崎寛史, 岩井貞憲, 宇都達郎, 大谷安見, 戸坂泰造, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 植田浩史, 野口聡, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2015.12

    Event date:
    2015.12
     
     
  • 無絶縁REBCOパンケーキコイルの遮断時のエネルギー回収特性評価

    勝俣一輝, 池田愛花, 大木隆広, JIA Yunhao, WANG Tao, 石山敦士, 野口聡, 門馬克敏, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2015.05

    Event date:
    2015.05
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(15年春)―含浸無絶縁コイル試験―

    岩井貞憲, 宮崎寛史, 大谷安見, 戸坂泰造, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2015.05

    Event date:
    2015.05
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(‘15年春)―極小口径10Tコイルの遮蔽電流磁場解析―

    植田浩史, 石山敦士, 野口聡, 岩井貞憲, 戸坂泰造, 宮崎寛史, 野村俊自, 来栖努, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2015.05

    Event date:
    2015.05
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(15年春)―プロジェクト進捗概要―

    戸坂泰造, 宮崎寛史, 岩井貞憲, 大谷安見, 高橋政彦, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2015.05

    Event date:
    2015.05
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(15年春)―均一磁場コイル最適化設計―

    野口聡, 石山敦士, 植田浩史, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2015.05

    Event date:
    2015.05
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(15年春)―1/2サイズコイル試験―

    宮崎寛史, 岩井貞憲, 大谷安見, 高橋政彦, 戸坂泰造, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2015.05

    Event date:
    2015.05
     
     
  • 高磁場MRI用高温超電導マグネットの開発

    戸坂泰造, 宮崎寛史, 岩井貞憲, 大谷安見, 高橋政彦, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 野口聡, 浦山慎一, 福山秀直

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2015.03

    Event date:
    2015.03
     
     
  • 無絶縁REBCOパンケーキコイルの通電特性解析と発生磁場の時間遅れに関する検討

    勝俣一輝, 大木隆広, 池田愛花, WANG Tao, 石山敦士, 野口聡, WANG Xudong, 渡部智則, 長屋重夫

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2015.03

    Event date:
    2015.03
     
     
  • 無絶縁及び部分絶縁REBCOパンケーキコイルの通電特性解析・評価

    荒川一誠, 南克彦, 中田恵理香, 大木隆広, 池田愛花, WANG Tao, 石山敦士, 野口聡, WANG Xudong, 渡部智則, 長屋重夫

    電気学会超電導機器研究会資料 

    Presentation date: 2015.01

    Event date:
    2015.01
     
     
  • 高温超伝導コイルを用いた高強度小型サイクロトロンの概念設計

    福田光宏, 植田浩史, 畑中吉治, 依田哲彦, 島田健司, 安田裕介, 石山敦士, 野口聡, 長屋重夫, 渡辺智則, 三上行雄, 吉田潤, 横田渉, 倉島俊, 宮脇信正, 吉田健一, 柏木啓次

    日本加速器学会年会(Web) 

    Presentation date: 2015

    Event date:
    2015
     
     
  • YOROI構造(SUS304)を適用したサイクロトロン超電導マグネットの変形解析と発生磁場精度の評価

    柏崎裕司, 辻義明, 石山敦士, 山川宏, WANG Xudong, 植田浩史, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2015

    Event date:
    2015
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(15年秋)REBCOマルチコイルにおける異常横磁界効果の評価

    今市洋平, WANG Tao, 石山敦士, 植田浩史, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集 

    Presentation date: 2015

    Event date:
    2015
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(15年秋)-REBCOマルチコイルにおける遮蔽電流による不整磁場の評価試験と解析-

    中園浩平, 持田歩, WANG Tao, 石山敦士, 植田浩史, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集 

    Presentation date: 2015

    Event date:
    2015
     
     
  • YOROI構造を応用したサイクロトロン超電導マグネットの磁場精度評価

    柏崎裕司, 辻義明, 石山敦士, 山川宏, WANG Xudong, 植田浩史, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2015

    Event date:
    2015
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(15年春)-REBCOマルチコイルにおける遮蔽電流による不整磁場の評価-

    中園浩平, 持田歩, 松見絢子, 今市洋平, WANG Tao, 石山敦士, 植田浩史, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集 

    Presentation date: 2015

    Event date:
    2015
     
     
  • 10T級小型REBCOコイルにおける遮蔽電流による不整磁場の低減

    中園浩平, 今市洋平, 松見絢子, 持田歩, WANG Tao, 石山敦士, 植田浩史, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2015

    Event date:
    2015
     
     
  • PEECモデルを用いた無絶縁及び部分絶縁REBCOコイルの遮断特性解析・評価

    OKI TAKAHIRO, IKEDA AIKA, ARAKAWA ISSEI, NAKADA ERIKA, MINAMI KATSUHIKO, WANG TAO, ISHIYAMA ATSUSHI, NOGUCHI SO, WANG XUDONG, WATANABE TOMONORI, NAGAYA SHIGEO

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.11

    Event date:
    2014.11
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(14年秋)―極小口径10Tコイル試験―

    MIYAZAKI HIROSHI, IWAI SADANORI, OTANI YASUMI, TAKAHASHI MASAHIKO, TOSAKA TAIZO, TASAKI KENJI, NOMURA SHUNJI, KURUSU TSUTOMU, ISHIYAMA ATSUSHI, UEDA HIROSHI, NOGUCHI SO, URAYAMA SHIN'ICHI, FUKUYAMA HIDENAO

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.11

    Event date:
    2014.11
     
     
  • 層間接触電気抵抗の不規則分布を考慮した無絶縁REBCOパンケーキコイルの遮断特性解析

    NAKADA ERIKA, IKEDA AIKA, OKI TAKAHIRO, ARAKAWA ISSEI, MINAMI KATSUHIKO, WANG TAO, ISHIYAMA ATSUSHI, WANG XUDONG, NOGUCHI SO

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.11

    Event date:
    2014.11
     
     
  • 無絶縁・部分絶縁REBCOパンケーキコイルの通電特性評価のための回路解析法

    ARAKAWA ISSEI, IKEDA AIKA, OKI TAKAHIRO, NAKADA ERIKA, MINAMI KATSUHIKO, WANG TAO, ISHIYAMA ATSUSHI, WANG XUDONG, NOGUCHI SO, WATANABE TOMONORI, NAGAYA SHIGEO

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.11

    Event date:
    2014.11
     
     
  • PEECモデルを用いた部分絶縁REBCOコイルの励磁特性解析・評価

    IKEDA AIKA, OKI TAKAHIRO, ARAKAWA ISSEI, NAKADA ERIKA, MINAMI KATSUHIKO, WANG TAO, ISHIYAMA ATSUSHI, ITO RYUSEI, NOGUCHI SO, WATANABE TOMONORI, NAGAYA SHIGEO

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.11

    Event date:
    2014.11
     
     
  • PEECモデルを用いた無絶縁REBCOコイルの過電流通電特性の解析

    MINAMI KATSUHIKO, NAKADA ERIKA, ARAKAWA ISSEI, IKEDA AIKA, OKI TAKAHIRO, WANG TAO, ISHIYAMA ATSUSHI, NOGUCHI SO, MONMA KATSUTOSHI, HAHN SEUNGYONG, IWASA YUKIKAZU, WANG XUDONG

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.11

    Event date:
    2014.11
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(’14年秋)―プロジェクト進捗―

    TOSAKA TAIZO, MIYAZAKI HIROSHI, IWAI SADANORI, OTANI YASUMI, TAKAHASHI MASAHIKO, TASAKI KENJI, NOMURA SHUNJI, KURUSU TSUTOMU, ISHIYAMA ATSUSHI, UEDA HIROSHI, NOGUCHI SO, URAYAMA SHIN'ICHI, FUKUYAMA HIDENAO

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.11

    Event date:
    2014.11
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(14年秋)―極小口径10Tコイル遮蔽電流解析―

    UEDA HIROSHI, ISHIYAMA ATSUSHI, NOGUCHI SO, TOSAKA TAIZO, MIYAZAKI HIROSHI, NOMURA SHUNJI, KURUSU TSUTOMU, URAYAMA SHIN'ICHI, FUKUYAMA HIDENAO

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.11

    Event date:
    2014.11
     
     
  • 無絶縁REBCOパンケーキコイルの過電流特性に関する数値解析・評価

    OKI TAKAHIRO, IKEDA AIKA, ARAKAWA ISSEI, MINAMI KATSUHIKO, NAKATA ERIKA, WANG TAO, ISHIYAMA ATSUSHI, WANG XUDONG, NOGUCHI SO, HAHN SEUNGYONG, IWASA YUKIKAZU

    電気学会超電導機器研究会資料 

    Presentation date: 2014.09

    Event date:
    2014.09
     
     
  • 高精度磁場発生用REBCOコイルにおける不整磁場の発生要因とその評価

    ISHIYAMA ATSUSHI, NOGUCHI SO, UEDA HIROSHI, TOSAKA TAIZO, MIYAZAKI HIROSHI, NOMURA SHUNJI, KURUSU TSUTOMU

    電気学会超電導機器研究会資料 

    Presentation date: 2014.09

    Event date:
    2014.09
     
     
  • 高磁場MRI用高温超電導磁石の開発(1)―プロジェクト概要―

    戸坂泰造, 宮崎寛史, 岩井貞憲, 大谷安見, 高橋政彦, 田崎賢司, 野村俊自, 来栖努, WANG Xudong, 石山敦士, 植田浩史, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.05

    Event date:
    2014.05
     
     
  • 無絶縁REBCO線材を巻線したm級パンケーキコイルの励磁特性解析・評価

    池田愛花, 大木隆広, WANG Tao, WANG Xudong, 石山敦士, 野口聡, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.05

    Event date:
    2014.05
     
     
  • 高磁場MRI用高温超電導磁石の開発(4)―巻線誤差の不整磁場への影響―

    石山敦士, WANG Xudong, 植田浩史, 野口聡, 戸坂泰造, 宮崎寛史, 野村俊自, 来栖努, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.05

    Event date:
    2014.05
     
     
  • 無絶縁REBCO線材を巻線したパンケーキコイルの過電流通電特性に関する数値解析・評価

    WANG Tao, 池田愛花, 大木隆宏, WANG Xudong, 石山敦士, 野口聡, HAHN Seungyong, 岩佐幸和

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.05

    Event date:
    2014.05
     
     
  • 高磁場MRI用高温超電導磁石の開発(3)―コイル配置最適化設計―

    石山敦士, WANG Xudong, 植田浩史, 野口聡, 戸坂泰造, 宮崎寛史, 野村俊自, 来栖努, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.05

    Event date:
    2014.05
     
     
  • 高磁場MRI用高温超電導磁石の開発(2)―極小口径10Tコイル―

    宮崎寛史, 岩井貞憲, 戸坂泰造, 田崎賢司, 野村俊自, 来栖努, WANG Xudong, 石山敦士, 植田浩史, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.05

    Event date:
    2014.05
     
     
  • 高磁場MRI用高温超電導磁石の開発(5)―遮蔽電流磁場の計算評価―

    石山敦士, WANG Xudong, 植田浩史, 野口聡, 戸坂泰造, 宮崎寛史, 野村俊自, 来栖努, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.05

    Event date:
    2014.05
     
     
  • 無絶縁REBCO線材を巻き線したパンケーキコイルの層間接触抵抗の解析・評価

    大木隆広, 池田愛花, WANG Tao, WANG Xudong, 石山敦士, 野口聡, SEUNGYONG Hahn, 岩佐幸和, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2014.05

    Event date:
    2014.05
     
     
  • YBCOパンケーキコイルにおける遮へい電流による不整磁場評価:実験

    持田歩, 今市洋平, 辻義明, 齋藤隼, 有谷友汰, WANG Xudong, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2014.03

    Event date:
    2014.03
     
     
  • No‐Insulation(NI)REBCOパンケーキコイルの層間接触抵抗評価実験

    大木隆広, 池田愛花, 荒川一誠, 南克彦, 中田恵理香, WANG Xudong, 石山敦士, 野口聡, HAHN Seungyong, IWASA Yukikazu

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2014.03

    Event date:
    2014.03
     
     
  • REBCOコイルの遮蔽電流磁場低減に関する検討

    植田浩史, 辻義明, 今市洋平, 持田歩, 有谷友汰, WANG Tao, WANG Xudong, 石山敦士, 野口聡

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2014.03

    Event date:
    2014.03
     
     
  • YBCOパンケーキコイルにおける遮へい電流による不整磁場評価:解析

    今市洋平, 辻義明, 持田歩, 有谷友汰, WANG Tao, WANG Xudong, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2014.03

    Event date:
    2014.03
     
     
  • 非絶縁REBCOパンケーキコイルの層間接触抵抗と励磁特性の評価

    WANG Xudong, WANG Tao, 増井裕太, 石山敦士, 伊藤竜誠, 野口聡, 植田浩史, HAHN Seungyong, 岩佐幸和

    電気学会超電導機器研究会資料 

    Presentation date: 2014.01

    Event date:
    2014.01
     
     
  • REBCO超電導コイルにおける遮へい電流の影響評価

    植田浩史, 野口聡, 道辻健太, 有谷友汰, WANG Tao, WANG Xudong, 石山敦士

    電気学会超電導機器研究会資料 

    Presentation date: 2014.01

    Event date:
    2014.01
     
     
  • 高温超伝導コイルを用いたスケルトン・サイクロトロン電磁石の設計研究

    FUKUDA MITSUHIRO, UEDA HIROSHI, HATANAKA KICHIJI, YORITA TETSUHIKO, ISHIYAMA ATSUSHI, WANG XUDONG, NAGAYA SHIGEO, WATANABE TOMONORI, NOGUCHI SATOSHI, YOKOTA WATARU, KURASHIMA SATOSHI, MIYAWAKI NOBUMASA

    日本加速器学会年会(Web) 

    Presentation date: 2014

    Event date:
    2014
     
     
  • REBCO線材の超電導特性のばらつきが遮蔽電流磁場に与える影響

    松見絢子, 今市洋平, 持田歩, 有谷友汰, 齋藤隼, WANG Tao, 石山敦士, 植田浩史, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集 

    Presentation date: 2014

    Event date:
    2014
     
     
  • 高温超電導サイクロトロンを想定した非円形REBCOパンケーキコイルの高機械強度化に向けた構造解析

    辻義明, 梅田大貴, WANG Xudong, 石山敦士, 山川宏, 植田浩史, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2014

    Event date:
    2014
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(14年秋)-REBCOマルチコイルにおける遮蔽電流による不整磁場の評価試験と解析-

    持田歩, 松見絢子, 今市洋平, 齋藤隼, 有谷友汰, WANG Tao, 石山敦士, 植田浩史, 植田浩史, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集 

    Presentation date: 2014

    Event date:
    2014
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(14年秋)-REBCOマルチコイルにおける遮蔽電流による不整磁場の評価試験と解析-

    持田歩, 松見絢子, 今市洋平, 齋藤隼, 有谷友汰, WANG Tao, 石山敦士, 植田浩史, 植田浩史, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集 

    Presentation date: 2014

    Event date:
    2014
     
     
  • 高磁場MRI用高温超電導磁石開発の進捗(14年秋)-REBCOマルチコイルにおける遮蔽電流による不整磁場の評価試験と解析-

    持田歩, 松見絢子, 今市洋平, 齋藤隼, 有谷友汰, WANG Tao, 石山敦士, 植田浩史, 植田浩史, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集 

    Presentation date: 2014

    Event date:
    2014
     
     
  • REBCOコイルにおける遮蔽電流による不整磁場の低減

    持田歩, WANG Tao, 有谷友汰, 斎藤隼, WANG Xudong, 石山敦士, 植田浩史

    低温工学・超電導学会講演概要集 

    Presentation date: 2014

    Event date:
    2014
     
     
  • REBCOマルチコイルにおける遮蔽電流による不整磁場の評価

    持田歩, 今市洋平, 齋藤隼, 有谷友汰, WANG Tao, 石山敦士, 植田浩史, 戸坂泰造, 宮崎寛史, 野村俊自, 来栖努

    電気学会超電導機器研究会資料 

    Presentation date: 2014

    Event date:
    2014
     
     
  • 次世代超電導サイクロトロンの開発:非円形YBCOパンケーキコイルの試作

    松見絢子, 辻義明, 斎藤隼, 梅田大貴, WANG Tao, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 長屋重夫

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2014

    Event date:
    2014
     
     
  • SMES応用を想定したYBCOコイルにおける常電導転移検出法

    池田愛花, 荒川一誠, 中田恵理香, 南克彦, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 長屋重夫

    電気学会全国大会講演論文集(CD-ROM) 

    Presentation date: 2014

    Event date:
    2014
     
     
  • REBCOコイルの遮へい電流磁場の低減に関する検討

    植田浩史, 齋藤隼, 有谷友汰, 梅田大貴, 道辻健太, 狩野開, WANG Tao, WANG Xudong, 石山敦士, 福田光宏, 畑中吉治, 野口聡

    低温工学・超電導学会講演概要集 

    Presentation date: 2013.12

    Event date:
    2013.12
     
     
  • YBCOパンケーキコイルにおける遮へい電流磁場評価実験

    有谷友汰, 斎藤隼, 梅田大貴, 狩野開, 道辻健太, WANG Tao, WANG Xudong, 石山敦士, 植田浩史, 福田光宏, 畑中吉治, 野口聡

    低温工学・超電導学会講演概要集 

    Presentation date: 2013.12

    Event date:
    2013.12
     
     
  • No‐insulation ReBCOコイルのターン間接触抵抗の影響についての数値シミュレーションによる検討

    野口聡, 伊藤竜誠, WANG Tao, WANG Xudong, 石山敦士, HAHN Seungyong, IWASA Yukikazu

    低温工学・超電導学会講演概要集 

    Presentation date: 2013.12

    Event date:
    2013.12
     
     
  • No‐Insulation REBCOパンケーキコイルの励磁特性に関する実験と簡易解析

    荒川一誠, 南克彦, 中田恵理香, 増井裕太, WANG Tao, WANG Xudong, 石山敦士, 野口聡, HAHN Seungyong, IWASA Yukikazu

    低温工学・超電導学会講演概要集 

    Presentation date: 2013.12

    Event date:
    2013.12
     
     
  • No‐Insulation REBCOパンケーキコイルの層間接触抵抗評価実験

    中田恵理香, 荒川一誠, 南克彦, 増井裕太, WANG Tao, WANG Xudong, 石山敦士, 野口聡, 渡部智則, 長屋重夫, HAHN Seungyong, IWASA Yukikazu

    低温工学・超電導学会講演概要集 

    Presentation date: 2013.12

    Event date:
    2013.12
     
     
  • 3Experiment and Simulation of Screening Current and Magnetic Field Distribution in HTS Coil

    UEDA Hiroshi, FUKUDA Mitsuhiro, HATANAKA Kichiji, NOGUCHI So, SAITO Jun, ARIYA Yuta, MICHITSUJI Kenta, WANG Tao, WANG Xudong, ISHIYAMA Atsushi

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2013.09

    Event date:
    2013.09
     
     
  • Y系ダブルパンケーキコイルの遮へい電流磁場解析

    植田浩史, 福田光宏, 畑中吉治, 野口聡, 齋藤隼, 有谷友汰, 狩野開, 道辻健太, WANG Tao, WANG Xudong, 石山敦士, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2013.05

    Event date:
    2013.05
     
     
  • 応用電磁気学:超電導機器応用のための電磁界数値解析II -有限要素法と境界要素法-

    植田 浩史, 石山 敦士  [Invited]

    低温工学 

    Presentation date: 2013.02

    Event date:
    2013.02
     
     
  • Design Optimization of Coils for Next Generation HTS Cyclotron

    UEDA Hiroshi, FUKUDA Mitsuhiro, HATANAKA Kichiji, WANG Xudong, ISHIYAMA Atsushi, NOGUCHI So, KASHIMA Naoji, NAGAYA Shigeo, MIYAHARA Nobuyuki

    Presentation date: 2013.01

    Event date:
    2013.01
     
     
  • SMES用YBCOコイルを想定した常電導転移検出法

    南克彦, 中田恵理香, 荒川一誠, 増井裕太, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2013

    Event date:
    2013
     
     
  • 次世代超電導サイクロトロンの開発:非円形YBCOパンケーキコイルの試作

    梅田大貴, 有谷友汰, 斎藤隼, 狩野開, 道辻健太, WANG Tao, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2013

    Event date:
    2013
     
     
  • 次世代超伝導サイクロトロンの開発:Y系ダブルパンケーキコイルの磁場精度評価

    有谷友汰, 斎藤隼, 狩野開, 道辻健太, WANG Tao, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2013

    Event date:
    2013
     
     
  • SMES応用を想定したYBCOモデルコイルの常電導転移検出実験

    荒川一誠, 南克彦, 中田恵理香, 増井裕太, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2013

    Event date:
    2013
     
     
  • Y系ダブルパンケーキコイルの遮へい電流磁場評価実験

    WANG Tao, 齋藤隼, 有谷友汰, 狩野開, 道辻健太, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2013

    Event date:
    2013
     
     
  • SMES用Y系超電導コイルのクエンチ検出と保護

    中田恵理香, 荒川一誠, 南克彦, 増井裕太, WANG Xudong, 石山敦士, 渡部智則, 長屋重夫, 植田浩史

    低温工学・超電導学会講演概要集 

    Presentation date: 2013

    Event date:
    2013
     
     
  • SMES応用を想定したYBCOモデルコイルの常電導転移・転流解析

    南克彦, 荒川一誠, 中田恵理香, 増井裕太, WANG Xudong, 石山敦士, 渡部智則, 長屋重夫, 植田浩史

    低温工学・超電導学会講演概要集 

    Presentation date: 2013

    Event date:
    2013
     
     
  • 伝導冷却パラフィン含浸モデルコイル伝熱特性評価実験

    荒川一誠, 増井裕太, WANG Xudong, 石山敦士, 渡辺智則, 平野直樹, 長屋重夫, 植田浩史

    電気学会全国大会講演論文集 

    Presentation date: 2013

    Event date:
    2013
     
     
  • YBCOパンケーキモデルコイルにおける巻線精度評価実験

    齋藤隼, 有谷友汰, 狩野開, 道辻健太, 矢崎真二郎, 柄澤彰良, 王旭東, 石山敦士, 宮原信幸, 植田浩史, 鹿島直二, 長屋重夫

    電気学会全国大会講演論文集 

    Presentation date: 2013

    Event date:
    2013
     
     
  • SMES応用を想定した伝導冷却YBCOモデルコイルの常電導転移検出実験法(その2):解析

    南克彦, 増井裕太, 大西秀明, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 平野直樹, 長屋重夫

    電気学会全国大会講演論文集 

    Presentation date: 2013

    Event date:
    2013
     
     
  • SMES応用を想定した伝導冷却YBCOモデルコイルの常電導転移検出法(その1):実験

    中田恵理香, 増井裕太, 大西秀明, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 平野直樹, 長屋重夫

    電気学会全国大会講演論文集 

    Presentation date: 2013

    Event date:
    2013
     
     
  • 高温超電導線材の耐放射線性評価:超電導特性

    有谷友汰, 齋藤隼, 道辻健太, 狩野開, WANG Xudong, 石山敦士, 植田浩史, 宮原信幸

    電気学会全国大会講演論文集 

    Presentation date: 2013

    Event date:
    2013
     
     
  • Experiments on Detection of Normal Transition for Cryocooler-cooled YBCO Model Coil for the Application of SMES-Current Measurement of Bundle Conductor-

    大西秀明, 増井裕太, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 平野直樹, 長屋重夫

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2013

    Event date:
    2013
     
     
  • 次世代超電導サイクロトロンの開発:コイル形状の設計最適化

    植田浩史, 福田光宏, 畑中吉治, 野口聡, 石山敦士, 長屋重夫, 鹿島直二, 宮原信幸

    低温工学・超電導学会講演概要集 

    Presentation date: 2012.11

    Event date:
    2012.11
     
     
  • 次世代超電導サイクロトロンの開発:遮へい電流の影響の検討

    植田浩史, 福田光宏, 畑中吉治, 野口聡, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 2012.11

    Event date:
    2012.11
     
     
  • 次世代超電導サイクロトロンの開発:開発課題

    石山敦士, WANG Xudong, 植田浩史, 福田光宏, 畑中吉治, 野口聡, 長屋重夫, 鹿島直二, 宮原信幸

    低温工学・超電導学会講演概要集 

    Presentation date: 2012.11

    Event date:
    2012.11
     
     
  • 3D Electromagnetic Simulation of Spatial and Temporal Behavior of Magnetic Field Distribution Caused by Shielding Current in HTS Coil for Accelerator Application

    UEDA Hiroshi, FUKUDA Mitsuhiro, HATANAKA Kichiji, NOGUCHI So, ISHIYAMA Atsushi

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2012.06

    Event date:
    2012.06
     
     
  • SMES用YBCOコイルを想定した伝導冷却下での銅モデルコイルの伝熱特性評価

    増井裕太, 琴寄拓哉, 石山敦士, 渡部智則, 平野直樹, 長屋重夫, 植田浩史

    低温工学・超電導学会講演概要集 

    Presentation date: 2012

    Event date:
    2012
     
     
  • 次世代超電導サイクロトロンの開発:高温超電導線材の中性子照射特性(超電導特性)

    道辻健太, 狩野開, 矢崎真二郎, 柄澤彰良, WANG Xudong, 石山敦士, 植田浩史, 宮原信幸

    低温工学・超電導学会講演概要集 

    Presentation date: 2012

    Event date:
    2012
     
     
  • SMES用伝導冷却YBCOコイルにおける常電導転移検出実験

    増井裕太, 大西秀明, 石山敦士, 渡部智則, 平野直樹, 長屋重夫, 植田浩史

    低温工学・超電導学会講演概要集 

    Presentation date: 2012

    Event date:
    2012
     
     
  • 次世代超電導サイクロトロンの開発:高温超電導線材の中性子照射特性(機械特性)

    道辻健太, 狩野開, 矢崎真二郎, 柄澤彰良, WANG Xudong, 石山敦士, 植田浩史, 宮原信幸

    低温工学・超電導学会講演概要集 

    Presentation date: 2012

    Event date:
    2012
     
     
  • 次世代超電導サイクロトロンの開発:高温超電導線材の中性子照射特性(放射化評価)

    宮原信幸, 狩野開, 道辻健太, 矢崎真二郎, 柄澤彰良, WANG Xudong, 石山敦士, 植田浩史

    低温工学・超電導学会講演概要集 

    Presentation date: 2012

    Event date:
    2012
     
     
  • 次世代超電導サイクロトロンの開発:YBCOパンケーキモデルコイルにおける巻線精度評価

    狩野開, 道辻健太, 矢崎真二郎, 柄澤彰良, WANG Xudong, 石山敦士, 宮原信幸, 植田浩史, 鹿島直二, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2012

    Event date:
    2012
     
     
  • 次世代超電導サイクロトロンの開発:YBCOパンケーキコイルの磁場精度解析

    WANG Tao, 石山敦士, 植田浩史, 福田光宏, 畑中吉治, 長屋重夫, 鹿島直二, 宮原信幸

    低温工学・超電導学会講演概要集 

    Presentation date: 2012

    Event date:
    2012
     
     
  • SMES用Y系超電導コイルにおけるクエンチ検出方法の検討

    増井裕太, 室町和輝, 鈴木貴裕, 大西秀明, 石山敦士, 渡部智則, 平野直樹, 長屋重夫, 植田浩史

    電気学会全国大会講演論文集 

    Presentation date: 2012

    Event date:
    2012
     
     
  • 加速器応用を想定した高温超電導コイルの遮へい電流と発生磁場分布の3次元解析

    植田浩史, 福田光宏, 畑中吉治, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 2012

    Event date:
    2012
     
     
  • Development of Next Generation HTS cyclotron : high-accuracy winding technique for pancake coil

    ISHIYAMA A.

    Abstracts of CSJ Conference 

    Presentation date: 2012

    Event date:
    2012
     
     
  • 医薬用たんぱく質の高速分離・精製・回収用高勾配磁気分離システムのフィルターの検討

    植田浩史, 我妻洸, 古瀬充穂, 淵野修一郎, 柁川一弘, 石山敦士, 小泉達雄

    低温工学・超電導学会講演概要集 

    Presentation date: 2011

    Event date:
    2011
     
     
  • 次世代高温超電導サイクロトロンのための高温超電導コイルの遮へい電流による磁場の空間的・時間的変化-(2)計算例-

    植田浩史, 福田光宏, 畑中吉治, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 2011

    Event date:
    2011
     
     
  • SMES用YBCO超電導コイルのクエンチ検出と保護に関する数値解析評価

    石山敦士, 大西秀明, WANG Xudong, 植田浩史, 渡部智則, 平野直樹, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2011

    Event date:
    2011
     
     
  • 次世代高温超電導サイクロトロンの試設計

    石山敦士, WANG Xudong, 植田浩史, 福田光宏, 畑中吉治, 長屋重夫, 鹿島直二, 宮原信幸, 横田渉

    低温工学・超電導学会講演概要集 

    Presentation date: 2011

    Event date:
    2011
     
     
  • Y系高温超電導モータの開発

    山田穣, 植田浩史, 和泉輝郎, 齊藤隆, 塩原融, 岩熊成卓, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 2011

    Event date:
    2011
     
     
  • 中性子照射による高温超電導体への影響

    琴寄拓哉, 神林佑, 柄澤彰良, 矢崎真二郎, 石山敦士, 宮原信幸, 植田浩史

    低温工学・超電導学会講演概要集 

    Presentation date: 2011

    Event date:
    2011
     
     
  • 次世代高温超電導サイクロトロンのための高温超電導コイルの遮へい電流による磁場の空間的・時間的変化-(1)3次元電磁場解析モデルおよび定式化-

    植田浩史, 福田光宏, 畑中吉治, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 2011

    Event date:
    2011
     
     
  • 次世代重粒子線がん治療用超電導加速器「先進ハイブリッドサイクロトロン」の試設計

    石山敦士, WANG Xudong, 福田光宏, 植田浩史, 畑中吉治, 長屋重夫, 鹿島直二, 宮原信幸, 横田渉

    電気学会全国大会講演論文集 

    Presentation date: 2011

    Event date:
    2011
     
     
  • 次世代重粒子線がん治療用超電導加速器「先進ハイブリッドサイクロトロン」の開発

    石山敦士, WANG Xudong, 福田光宏, 植田浩史, 畑中吉治, 長屋重夫, 鹿島直二, 宮原信幸, 横田渉

    電気学会全国大会講演論文集 

    Presentation date: 2011

    Event date:
    2011
     
     
  • Development of Next Generation HTS Cyclotron

    ISHIYAMA A.

    Abstracts of CSJ Conference 

    Presentation date: 2011

    Event date:
    2011
     
     
  • Trial Design of Next Generation HTS Cyclotron

    ISHIYAMA A.

    Abstracts of CSJ Conference 

    Presentation date: 2011

    Event date:
    2011
     
     
  • YBCO超電導線材の過電流パルス通電による特性劣化試験

    WANG XUDONG, ARAI MICHIO, ISHIYAMA ATSUSHI, SAITO TAKASHI, AOKI YUJI, YAGI MASASHI, SAKAI NAOMICHI, FUJIWARA NOBORU

    低温工学・超電導学会講演概要集 

    Presentation date: 2010.05

    Event date:
    2010.05
     
     
  • SMES用伝導冷却高温超電導コイルのクエンチ保護

    室町和輝, 鈴木貴裕, 青木佳明, 植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2010

    Event date:
    2010
     
     
  • REBCO超電導線材の過電流パルス通電による特性劣化要因について

    金光雅也, 新井道生, WANG Xudong, 植田浩史, 石山敦士, 斉藤隆, 大松一也, 大屋正義, 和泉輝郎, 藤原昇

    低温工学・超電導学会講演概要集 

    Presentation date: 2010

    Event date:
    2010
     
     
  • SMES用伝導冷却Y系超電導モデルコイルの通電・伝熱特性評価

    鈴木貴裕, 室町和輝, 青木佳明, 植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2010

    Event date:
    2010
     
     
  • 銅メッキYBCO超電導線材の疲労特性試験

    鈴木貴裕, 川井優季, 青木佳明, 植田浩史, 石山敦士, 鹿島直二, 渡辺智則, 平野直樹, 山本潔

    電気学会全国大会講演論文集 

    Presentation date: 2010

    Event date:
    2010
     
     
  • SMES用冷凍機伝導冷却Y系超電導コイルを想定した銅ダミーコイルの熱特性評価解析

    室町和輝, 青木佳明, 川井優季, 植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    電気学会全国大会講演論文集 

    Presentation date: 2010

    Event date:
    2010
     
     
  • 高温超電導線材の中性子照射実験

    青木徹, 陸旭棟, 神林佑, 植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 宮原信幸

    電気学会全国大会講演論文集 

    Presentation date: 2010

    Event date:
    2010
     
     
  • AC Loss Evaluation of SMES Coils with Y-based Coated Conductor

    柁川一弘, 船木和夫, 植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    超伝導システム科学研究センター報告 

    Presentation date: 2010

    Event date:
    2010
     
     
  • YBCO超電導線材の交流過電流通電特性

    児島健太郎, 新井道生, 河野秀太郎, WANG Xudong, 植田浩史, 石山敦士, 大屋正義, 湯村洋康, 藤原昇

    電気学会全国大会講演論文集 

    Presentation date: 2010

    Event date:
    2010
     
     
  • 275kV系統YBCO超電導ケーブルの定常運転時の伝熱特性

    神谷侑司, 百足弘史, 佐藤俊祐, WANG Xudong, 植田浩史, 石山敦士, 八木正史, 藤原昇

    電気学会全国大会講演論文集 

    Presentation date: 2010

    Event date:
    2010
     
     
  • 球状バルク超電導体のアクティブ磁気浮上における安定性評価

    WANG Tao, 陸旭棟, 青木徹, 阿部昂機, 植田浩史, 我妻洸, 石山敦士, 岩本晃史, 柳長門, 三戸利行

    電気学会全国大会講演論文集 

    Presentation date: 2010

    Event date:
    2010
     
     
  • Neutron Iradiation Experiment of HTS for Prticle Radiation Therapy of Cancer

    陸旭棟, 青木徹, 神林佑, 植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 宮原信幸

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2010

    Event date:
    2010
     
     
  • Stability and Protection of Cryocooler-cooled YBCO Coils for SMES with Toroidal Arrangement

    植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2010

    Event date:
    2010
     
     
  • 医薬用たんぱく質の高速分離・精製・回収用高勾配磁気分離システムの回収率改善の検討

    植田浩史, 石山敦士, 我妻洸, 古瀬充穂, 淵野修一郎, 柁川一弘, 小泉達雄

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • 医薬用たんぱく質の高速分離・精製・回収用高勾配磁気分離システムの回収率改善の検討

    植田浩史, 石山敦士, 我妻洸, 古瀬充穂, 淵野修一郎, 柁川一弘, 小泉達雄

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • YBCO超電導線材の交流過電流通電特性

    百足弘史, 新井道生, 河野秀太郎, WANG Xudong, 植田浩史, 石山敦士, 斎藤隆, 青木裕治, 八木正史, 藤原昇

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • 高温超電導線材の疲労特性評価試験装置

    青木佳明, 川井優季, 植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • 断面構造の異なるNb3Sn素線のCIC導体内における超電導特性の評価

    梶谷秀樹, 植田浩史, 石山敦士, 村上陽之, 小泉徳潔, 奥野清

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • 66kV系統高温超電導ケーブルの過電流通電特性評価

    瓜生季邦, 百足弘史, 佐藤俊祐, WANG Xudong, 植田浩史, 石山敦士, 大屋正義, 増田孝人, 藤原昇

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • 銅メッキYBCO超電導線材の疲労特性試験

    青木佳明, 川井優季, 植田浩史, 石山敦士, 鹿島直二, 渡辺智則, 平野直樹, 山本潔

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • 275kV系統YBCO超電導ケーブルの過電流通電特性解析

    WANG Xudong, 植田浩史, 石山敦士, 八木正史, 藤原昇

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • YBCO超電導コイルの安定性と保護

    植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • 高温超電導線材の中性子照射実験

    青木徹, 陸旭棟, 植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 宮原信幸

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • 球状バルク超電導体のアクティブ磁気浮上における安定性評価

    WANG Tao, 陸旭棟, 青木徹, 阿部昂機, 植田浩史, 我妻洸, 石山敦士, 岩本晃史, 柳長門, 三戸利行

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • 医薬用たんぱく質の高速分離・精製・回収用アフィニティー磁性ナノビーズ

    我妻洸, 淵野修一郎, 井村知弘, 古瀬充穂, 植田浩史, 石山敦士, 柁川一弘, 三宅新一, 五十嵐弘

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • 球状バルク超電導体の浮上安定性評価

    植田浩史, 陸旭棟, 青木徹, 石山敦士, 岩本晃史, 柳長門, 三戸利行

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • 275kV系統YBCO超電導ケーブルの定常運転時の伝熱特性

    瓜生季邦, 百足弘史, 佐藤俊祐, WANG Xudong, 植田浩史, 石山敦士, 八木正史, 齊藤隆, 青木裕治, 藤原昇, 塩原融

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • 数値シミュレーションによるTFコイル用CIC導体内の電流分布解析

    梶谷秀樹, 植田浩史, 石山敦士, 村上陽之, 小泉徳潔, 奥野清

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • 66kV系統YBCO超電導ケーブルの過電流通電特性解析

    WANG Xudong, 植田浩史, 石山敦士, 大屋正義, 湯村洋康, 藤原昇, 塩原融

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • コイル巻線化されたYBCO集合化導体の常電導伝播特性解析

    植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • スラッシュ窒素冷却下における高温超電導線材の過電流通電特性

    百足弘史, 瓜生季邦, 佐藤俊祐, WANG Xudong, 植田浩史, 石山敦士, 淵野修一郎, 古瀬充穂, 池内正充, 大野隆介

    低温工学・超電導学会講演概要集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • スラッシュ窒素の電気絶縁特性

    淵野修一郎, 古瀬充穂, 名取尚武, 池内正充, 大野隆介, 石山敦士, 植田浩史

    電気学会全国大会講演論文集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • AC Loss Evaluation of Pancake Coils for Y-based SMES with Toroidal Arrangement

    柁川一弘, 船木和夫, 植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2009

    Event date:
    2009
     
     
  • Thermal Characteristics of 275kV Class YBCO Superconducting Power Cable-Effect of Dielectric Loss-

    WANG Xudong, 植田浩史, 石山敦士, 八木正史, 藤原昇

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2009

    Event date:
    2009
     
     
  • YBCO超電導ケーブルの過電流通電特性

    WANG Xudong, 植田浩史, 石山敦士, 八木正史, 向山晋一, 鹿島直二, 長屋重夫, 塩原融

    電気学会全国大会講演論文集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • スラッシュ窒素冷却下における高温超電導線材の過電流通電特性(実験)

    瓜生季邦, 百足弘史, 佐藤俊祐, WANG Xudong, 植田浩史, 石山敦士, 淵野修一郎, 古瀬充穂, 池内正充, 大野隆介

    電気学会全国大会講演論文集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • YBCO超電導線材の疲労特性

    青木佳明, 田中洋輔, 川井優季, 植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 塩原融

    電気学会全国大会講演論文集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • YBCO超電導線材の過電流パルス通電試験前後における層間接触評価

    梶谷秀樹, 新井道生, 河野秀太郎, 西尾幸恭, 植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 八木正史, 向山晋一, 加藤英幸, 塩原融

    電気学会全国大会講演論文集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • スラッシュ窒素冷却下における高温超電導線材の過電流通電特性(数値解析)

    百足弘史, 瓜生季邦, 佐藤俊祐, WANG Xudong, 植田浩史, 石山敦士, 淵野修一郎, 古瀬充穂, 池内正充, 大野隆介

    電気学会全国大会講演論文集 

    Presentation date: 2009

    Event date:
    2009
     
     
  • 医薬用たんぱく質の高速分離・精製・回収用高勾配磁気分離システム

    我妻洸, 淵野修一郎, 古瀬充穂, 柁川一弘, 植田浩史, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 2008

    Event date:
    2008
     
     
  • 医薬用たんぱく質の高勾配磁気分離システムによる高速分離・精製・回収用フィルターの設計

    植田浩史, 石山敦士, 我妻洸, 淵野修一郎, 古瀬充穂, 柁川一弘

    低温工学・超電導学会講演概要集 

    Presentation date: 2008

    Event date:
    2008
     
     
  • 球状バルク超電導体のアクティブ磁気浮上における安定性評価

    陸旭棟, 青木徹, 石垣善弘, 植田浩史, 我妻洸, 石山敦士, 岩本晃史, 柳長門, 三戸利行

    低温工学・超電導学会講演概要集 

    Presentation date: 2008

    Event date:
    2008
     
     
  • 高温超電導線材の放射化特性

    植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 宮原信幸

    低温工学・超電導学会講演概要集 

    Presentation date: 2008

    Event date:
    2008
     
     
  • YBCO超電導線材の疲労特性

    川井優季, 田中洋輔, 植田浩史, 石山敦士, 飯島康裕, 斉藤隆, 鹿島直二, 長屋重夫, 山田穣, 塩原融

    低温工学・超電導学会講演概要集 

    Presentation date: 2008

    Event date:
    2008
     
     
  • YBCO超電導線材の疲労特性

    川井優季, 田中洋輔, 植田浩史, 石山敦士, 飯島康裕, 斉藤隆, 鹿島直二, 長屋重夫, 山田穣, 塩原融

    低温工学・超電導学会講演概要集 

    Presentation date: 2008

    Event date:
    2008
     
     
  • YBCO超電導線材の過電流パルス通電による特性劣化と層間剥離

    河野秀太郎, WANG Xudong, 西尾幸恭, 植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 八木正史, 向山晋一, 加藤英幸, 塩原融

    低温工学・超電導学会講演概要集 

    Presentation date: 2008

    Event date:
    2008
     
     
  • 球状バルク超電導体のアクティブ磁気浮上における安定性評価

    陸旭棟, 青木徹, 石垣善弘, 植田浩史, 我妻洸, 石山敦士, 岩本晃史, 柳長門, 三戸利行

    低温工学・超電導学会講演概要集 

    Presentation date: 2008

    Event date:
    2008
     
     
  • 10m級YBCO超電導ケーブルの過電流通電特性

    WANG Xudong, 植田浩史, 石山敦士, 八木正史, 向山晋一, 鹿島直二, 長屋重夫, 塩原融

    低温工学・超電導学会講演概要集 

    Presentation date: 2008

    Event date:
    2008
     
     
  • Strain and Fatigue Properties of YBCO coated conductors

    石山敦士, 田中洋輔, 川井優季, 佐藤俊祐, 植田浩史, 塩原融, 山田穣, 飯島康裕, 斉藤隆, 鹿島直二, 長屋重夫

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2008

    Event date:
    2008
     
     
  • 球状バルク超電導体のアクティブ磁気浮上の安定・位置制御

    陸旭棟, 菅兼治, 植田浩史, 我妻洸, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 2008

    Event date:
    2008
     
     
  • Radioactive analyses of HTS conductors

    植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 宮原信幸

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2008

    Event date:
    2008
     
     
  • コイル保護に基づくYBCO線材の安定化層厚の決定-SMES用コイルを想定して-

    川井優季, 植田浩史, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 2008

    Event date:
    2008
     
     
  • Levitation Stability of Active Magnetic Levitation using Sphere-shaped HTS bulk

    石垣善弘, 陸旭棟, 植田浩史, 我妻洸, 石山敦士

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2008

    Event date:
    2008
     
     
  • YBCO超電導ケーブル導体の過電流特性解析

    佐藤俊祐, WANG Xudong, 西尾幸恭, 植田浩史, 石山敦士, 八木正史, 向山晋一, 鹿島直二, 長屋重夫, 塩原融

    電気学会全国大会講演論文集 

    Presentation date: 2008

    Event date:
    2008
     
     
  • Overcurrent Characteristics of 10-m YBCO Superconducting Cable-Experiments and Simulations-

    WANG Xudong, 植田浩史, 石山敦士, 八木正史, 向山晋一, 鹿島直二, 長屋重夫, 塩原融

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2008

    Event date:
    2008
     
     
  • Ic分布を考慮したYBCO超電導線材の常電導転移・伝播特性

    WANG Xudong, 土屋元計, 植田浩史, 石山敦士, 塩原融

    低温工学・超電導学会講演概要集 

    Presentation date: 2007

    Event date:
    2007
     
     
  • 球状バルク超電導体のアクティブ磁気浮上における安定・位置制御

    菅兼治, 陸旭棟, 植田浩史, 我妻洸, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 2007

    Event date:
    2007
     
     
  • コイル保護に基づくYBCO線材の安定化層厚の決定-SMES用コイルを想定して

    番場貞徳, 植田浩史, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 2007

    Event date:
    2007
     
     
  • 単層1m級YBCO超電導ケーブル導体の過電流通電特性(2.解析)

    植田浩史, 西尾幸恭, 岩田拓也, WANG Xudong, 石山敦士, 八木正史, 向山晋一, 塩原融

    低温工学・超電導学会講演概要集 

    Presentation date: 2007

    Event date:
    2007
     
     
  • CIC導体内におけるNb3Sn素線の超電導特性の数値解析・評価

    村上陽之, 植田浩史, 石山敦士, 小泉徳潔, 奥野清

    低温工学・超電導学会講演概要集 

    Presentation date: 2007

    Event date:
    2007
     
     
  • YBCO超電導ケーブル導体の過電流特性解析

    石山敦士, WANG Xudong, 西尾幸恭, 植田浩史, 八木正史, 向山晋一, 鹿島直二, 長屋重夫, 塩原融

    低温工学・超電導学会講演概要集 

    Presentation date: 2007

    Event date:
    2007
     
     
  • 単層1m級YBCO超電導ケーブルの過電流通電特性評価(1.実験)

    石山敦士, 西尾幸恭, WANG Xudong, 岩田拓也, 植田浩史, 八木正史, 向山晋一, 塩原融

    低温工学・超電導学会講演概要集 

    Presentation date: 2007

    Event date:
    2007
     
     
  • Over-Current Characteristics of 1m-long Superconducting Model Cable using YBCO Coated Conductors-Experiment and Simulation-

    植田浩史, 西尾幸恭, WANG Xudong, 石山敦士, 八木正史, 向山晋一, 鹿島直二, 長屋重夫, 塩原融

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2007

    Event date:
    2007
     
     
  • LHD超電導導体の過渡安定性解析

    野口聡, 五十嵐一, 石山敦士, 柳長門, 今川信作

    低温工学・超電導学会講演概要集 

    Presentation date: 2006.11

    Event date:
    2006.11
     
     
  • 着磁したバルク超電導体を二次側走行子とするリニア同期アクチュエータの特性評価

    菅兼治, 植田浩史, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 2006

    Event date:
    2006
     
     
  • 高温超電導コイルのクエンチ保護に関する一考察

    番場貞徳, 鈴木公三, 中里しょう平, 安東武利, 植田浩史, 石山敦士, 塩原融

    電気学会全国大会講演論文集 

    Presentation date: 2006

    Event date:
    2006
     
     
  • マウス用生体磁気計測システムの開発

    石山 敦士, 小野 弓絵

    超電導応用研究会シンポジウム講演論文集 

    Presentation date: 2005.03

    Event date:
    2005.03
     
     
  • 高温超電導コイルのクエンチ保護に関する一考察

    仲寛徳, 牛久裕輔, 安東武利, 岩田拓也, 田中康武, 村上陽之, 植田浩史, 石山敦士, 塩原融

    低温工学・超電導学会講演概要集 

    Presentation date: 2005

    Event date:
    2005
     
     
  • バルク超電導体を用いた浮上搬送装置の設計・特性評価

    土屋元計, 土屋賢史, 東谷智史, 久藤勇哉, 植田浩史, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 2005

    Event date:
    2005
     
     
  • 3D Analysis of Electromagnetic field including bulk superconductor using Fast Multipole Method

    植田浩史, 東谷智史, 土屋賢史, 土屋元計, 石山敦士

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2005

    Event date:
    2005
     
     
  • 系統安定化用SMESを想定した高温超電導コイルの最適化設計

    石山敦士, 野口聡, 秋田調, 高祖聖一, 辰田昌功

    低温工学・超電導学会講演概要集 

    Presentation date: 2004.05

    Event date:
    2004.05
     
     
  • Optimal design of HTS SMES coil for power system stabilization

    ISHIYAMA A, NOGUCHI S, AKITA S, KOUSO S, TATSUTA Y

    電気学会研究会資料. ASC, 超電導応用電力機器 

    Presentation date: 2004.01

    Event date:
    2004.01
     
     
  • バルク超電導体を用いた鉛直方向リニア・アクチュエータ

    伊藤祐介, 田代靖貴, 植田浩史, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 2004

    Event date:
    2004
     
     
  • YBCO線材の常電導転移・伝播特性

    仲寛徳, 牛久祐輔, 柳井正浩, 植田浩史, 石山敦士, 塩原融

    電気学会全国大会講演論文集 

    Presentation date: 2004

    Event date:
    2004
     
     
  • 着磁したバルク超電導体を二次側走行子とするリニア同期アクチュエータの試作と基礎実験

    広橋雅元, 柴田貴広, 佐藤飛鳥, 植田浩史, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 2004

    Event date:
    2004
     
     
  • Analysis of Electromagnetic field including Superconduting Bulk

    植田浩史, 伊藤学, 森崎徹, 石山敦士

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2004

    Event date:
    2004
     
     
  • バルク超電導体を用いた浮上搬送装置-永久磁石の磁極配置による浮上特性への影響(その2)-

    東谷智史, 土屋賢史, 久藤勇哉, 岩本真実, 植田浩史, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 2004

    Event date:
    2004
     
     
  • 系統安定化用SMESを想定した高温超電導コイルの通電特性評価

    石山敦士, 植田浩史, 秋田調, 笠原奉文, 高祖聖一

    電気学会電力・エネルギー部門大会論文集 

    Presentation date: 2003

    Event date:
    2003
     
     
  • バルク超電導体を用いた浮上搬送装置 2つのバルク体を対向させたときの浮上特性実験と解析

    久藤勇哉, 岩本真実, 赤松猛, 植田浩史, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 2003

    Event date:
    2003
     
     
  • X-Y Levitating Transporter using HTS Bulks. Levitating Characteristics when using Two HTS Bulks.

    赤松猛, 岩本真実, 植田浩史, 石山敦士

    電気学会静止器研究会資料 

    Presentation date: 2003

    Event date:
    2003
     
     
  • The Vertical Direction Transport System using YBCO Bulk and Multiple Electromagnets.

    鴨志田亮太, 菅原淳史, 植田浩史, 石山敦士

    電気学会静止器研究会資料 

    Presentation date: 2003

    Event date:
    2003
     
     
  • 着磁されたバルク超電導体の交流磁界印加特性解析

    森崎徹, 伊藤学, 植田浩史, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 2003

    Event date:
    2003
     
     
  • 複数のコイルとバルク超電導体による鉛直方向搬送実験

    田代靖貴, 菅原淳史, 鴨志田亮太, 植田浩史, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 2003

    Event date:
    2003
     
     
  • バルク超電導体を二次側走行子とするリニア同期アクチュエータの始動特性実験

    佐藤飛鳥, 井比敏男, 高橋淳, 植田浩史, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 2003

    Event date:
    2003
     
     
  • Change of N1m Latency by Simultaneous Visual - Audio Stimulation

    ADACHI Shinobu, KOBAYASHI Atsushi, SHIROTO Takuya, ONO Yumie, ISHIYAMA Atsushi, KASAI Naoko, TONOIKE Mitsuo

    Presentation date: 2002.04

    Event date:
    2002.04
     
     
  • Four Sources Localization Using Combined Method of Genetic Algorithm and Simulated Annealing

    KOBAYASHI Atsushi, SHIROTO Takuya, ADACHI Shinobu, ONO Yumie, ISHIYAMA Atsushi, KASAI Naoko, TONOIKE Mitsuo

    Presentation date: 2002.04

    Event date:
    2002.04
     
     
  • バルク超電導体を用いた自由に方向転換可能な浮上搬送装置 浮上力・復元力特性評価

    岩本真実, 赤松猛, 寺西康幸, 植田浩史, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 2002

    Event date:
    2002
     
     
  • 複数の電磁石とバルク超電導体による鉛直方向アクティブ連続磁気浮上

    菅原淳史, 鴨志田亮太, 林浩幹, 植田浩史, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 2002

    Event date:
    2002
     
     
  • 着磁されたバルク超電導体の交流磁界印加特性

    伊藤学, 清水英仁, 植田浩史, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 2002

    Event date:
    2002
     
     
  • Magnetic Levitation with High-Tc Superconducting Bulk and Multiple Electromagnets.

    鴨志田亮太, 林浩幹, 植田浩史, 石山敦士

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2002

    Event date:
    2002
     
     
  • 複数の電磁石とバルク超電導体による連続アクティブ磁気浮上

    鴨志田亮太, 林浩幹, 植田浩史, 石山敦士

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2001

    Event date:
    2001
     
     
  • 着磁されたバルク超電導体の交流磁界印加特性

    清水英仁, 大山俊章, 植田浩史, 石山敦士, 津田理

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2001

    Event date:
    2001
     
     
  • バルク超電導体と複数の電磁石による鉛直方向アクティブ磁気浮上

    林浩幹, 植田浩史, 石山敦士, 津田理

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2001

    Event date:
    2001
     
     
  • 磁気遮へい型超電導限流器の動作特性評価

    植田浩史, 門裕之, 石山敦士, 市川路晴

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2001

    Event date:
    2001
     
     
  • Numerical Analysis of electromagnetic Field includes Superconducting Bulk and Its Applications.

    石山敦士, 植田浩史, 大山俊彰, 村松亮, 津田理, 野口聡

    電気学会静止器研究会資料 

    Presentation date: 2000.08

    Event date:
    2000.08
     
     
  • Source localization with olfactory MEG using noise reduction method of time-frequency analysis.

    小野弓絵, 奥村雅行, 高田薫, 野村公比呂, 黒沢雅徳, 石山敦士, 葛西直子, 山口雅彦, 外池光雄

    電気学会マグネティックス研究会資料 

    Presentation date: 2000

    Event date:
    2000
     
     
  • Signal Processing using Wavelet Transform for MEG noise reduction.

    小野弓絵, 奥村雅行, 高田薫, 野村公比呂, 黒沢雅徳, 石山敦士, 中川誠司, 岩木直, 外池光雄

    電気学会マグネティックス研究会資料 

    Presentation date: 2000

    Event date:
    2000
     
     
  • 複数の電磁石とバルク超電導体による鉛直方向連続磁気浮上

    林浩幹, 植田浩史, 石山敦士, 津田理

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2000

    Event date:
    2000
     
     
  • 磁気遮へい型超電導限流器の動作特性評価

    門裕之, 市川路晴, 植田浩史, 石山敦士

    電気学会電力・エネルギー部門大会論文集 

    Presentation date: 2000

    Event date:
    2000
     
     
  • 磁気遮へい型超電導限流器の動作特性評価

    植田浩史, 石山敦士, 門裕之, 市川路晴

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 2000

    Event date:
    2000
     
     
  • Magnetic Shielding Characteristics of Superconducting Bulk Cylinder for Magnetic Shielding Type Superconducting Fault Current Limiter.

    中津川潤之介, 野口聡, 石山敦士, 門裕之, 市川路晴

    電気学会静止器研究会資料 

    Presentation date: 1998.12

    Event date:
    1998.12
     
     
  • 磁気遮へい型限流器用超電導バルク円筒体の磁気遮へい特性 実験と解析

    野口聡, 中津川潤之介, 石山敦士, 門裕之, 市川路晴

    低温工学・超電導学会講演概要集 

    Presentation date: 1998.10

    Event date:
    1998.10
     
     
  • 感度解析を用いた高磁界・高均一超電導マグネットの最適化設計

    野口聡, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 1998.03

    Event date:
    1998.03
     
     
  • 磁気遮へい型限流器用超電導バルク円筒体の磁気遮へい特性

    門裕之, 市川路晴, 野口聡, 中津川潤之介, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 1998.03

    Event date:
    1998.03
     
     
  • Magnetic Shielding Characteristics of Superconducting Bulk Cylinder for Magnetic Shielding Type Superconducting Fault Current Limitter.

    KADO HIROYUKI, ICHIKAWA MICHIHARU, NOGUCHI SO, NAKATSUGAWA JUNNOSUKE, ISHIYAMA ATSUSHI

    低温工学・超電導学会講演概要集 

    Presentation date: 1997.11

    Event date:
    1997.11
     
     
  • An Optimal Design Method for High-Field Superconducting Magnets Using Genetic Algorithm.

    野口聡, 石山敦士

    計算電気・電子工学シンポジウム論文集 

    Presentation date: 1995.03

    Event date:
    1995.03
     
     
  • Application of genetic algorithm to design of intense magnetic field superconducting magnet.

    野口聡, 石山敦士

    電気学会電線・ケーブル研究会資料 

    Presentation date: 1995.01

    Event date:
    1995.01
     
     
  • ノッチ付き高磁界・高均一超電導マグネットの最適設計

    野口聡, 坂原淳史, 石山敦士

    低温工学・超電導学会講演概要集 

    Presentation date: 1994.04

    Event date:
    1994.04
     
     
  • Simulated Annealing法に基づく高磁界・高均一超電導マグネットの最適設計法

    野口聡, 坂原淳史, 石山敦士

    電気学会全国大会講演論文集 

    Presentation date: 1994.03

    Event date:
    1994.03
     
     
  • Optimum design of superconducting magnet with a strong magnetic field and high uniformity.

    坂原淳史, 野口聡, 石山敦士

    電気学会超電導応用電力機器研究会資料 

    Presentation date: 1994.02

    Event date:
    1994.02
     
     
  • NbTi/CuNi超電導線材の常電導伝搬特性

    津田 理, 石山 敦士

    電気学会論文誌 B 電力・エネルギー部門誌  電気学会

    Presentation date: 1993.08

    Event date:
    1993.08
     
     
  • 場の数値解析手法と数理計画法の併用による電磁界問題における最適化について (最適化<特集>)

    横井 利彰, 石山 敦士, 小貫 天

    電気学会論文誌 C 電子・情報・システム部門誌  電気学会

    Presentation date: 1989.04

    Event date:
    1989.04
     
     
  • 境界要素法と最適化手法の併用による均一磁界発生用マグネットの最適設計について

    石山 敦士

    電気学会論文誌 B 電力・エネルギー部門誌  電気学会

    Presentation date: 1986.11

    Event date:
    1986.11
     
     
  • 超電導電力貯蔵装置におけるうず電流の影響

    石山 敦士, 我妻 洸

    電気学会論文誌 B 電力・エネルギー部門誌  電気学会

    Presentation date: 1982.09

    Event date:
    1982.09
     
     
  • 超電導マグネットを用いたエネルギ-貯蔵装置の制御方式と充放電実験

    石山 敦士, 我妻 洸, 十川 忠男

    電気学会論文誌 B 電力・エネルギー部門誌  電気学会

    Presentation date: 1982.03

    Event date:
    1982.03
     
     

▼display all

Research Projects

  • Realization of highly robust, high-performance, low-cost high-temperature superconducting coil systems without protection

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2022.04
    -
    2025.03
     

  • Establishment of design principle and basic technology for next generation medical high temperature superconducting skeleton-cyclotron

    Project Year :

    2018.06
    -
    2023.03
     

  • 次世代医療用高温超伝導スケルトン・サイクロトロンの設計原理・開発基盤の確立

    日本学術振興会 科学研究費助成事業(基盤研究A)代表 

    Project Year :

    2018.04
    -
    2022.03
     

  • Basic Study on innovative high temperature superconducting coil technology realizing ultra-high magnetic field and ultra-high storage density

    Project Year :

    2016.04
    -
    2018.03
     

     View Summary

    The Superconducting Magnetic Energy Storage (SMES) device has the feature of a long lifetime and instantaneous response of large power. However, the storage density is much inferior to that of Li-ion batteries and the like. Therefore, with the aim of ultra-high magnetic field and ultra-high storage density (600 kWh / m 3) of high-temperature superconducting coil for SMES, the feasibility of ultra-high storage density SMES by applying "Super-YOROI" high-strength coil support structure and "interlayer electric resistance control technology" which realizes both high current density and high thermal stability, has been evaluated and verified by numerical analyses

  • Establishment of 5H Superconducting Coil System Technology for Next Generation Medical Cuclotron

    Project Year :

    2014.06
    -
    2018.03
     

     View Summary

    With the purpose of developing a superconducting accelerator "Advanced Hybrid Cyclotron (AHC)" for heavy particle cancer therapy, we have aimed at establishing basic technology for development of REBCO high-temperature superconducting coil system which enables high mechanical strength, high current density, high stability, high magnetic field and high precision magnetic field. And the effectiveness of "Super-YOROI coil structure" for high strength and high magnetic field, "no-insulation coil winding method" for compatibility between high current density and high thermal stability, and " Method for reducing the shielding current magnetic field " was verified by numerical analyses and experiments

  • Research on High Strength Design Technique for High Temperature Superconducting Magnet

    Project Year :

    2014.04
    -
    2016.03
     

     View Summary

    It is very necessary to achieve the high temperature superconducting coil to upgrade the performance of high field superconducting magnet such as MRI and NMR. The upgrading of the mechanical property of the high temperature superconducting coil is a biggest technical problem because of the large Lorentz force induced by the high current density and high field. In this research, a series of experiments and simulations were performed on a YOROI coil structure. A reinforcing design for the high temperature superconducting coil with the hoop stress of 1.2 GPa and current density of 200 A/mm2 was successfully achieved. The high strength design technique for the high temperature superconducting coil was also successfully developed

  • Design study on superconducting coil system of cyclotron for nuclear waste disposal

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2014.04
    -
    2016.03
     

    Ishiyama Atsushi, NOGUCHI So, UEDA Hiroshi, YAMAKAWA Hiroshi

     View Summary

    We have been developing superconducting REBCO coil systems for a cyclotron with a output power of 30MW for nuclear waste disposal. At first, we carried out conceptual design of the REBCO coil system for a 30MW cyclotron. The REBCO coils require a high mechanical strength in order to overcome the huge hoop stress. In our previous study, we have proposed a coil structure named “YOROI-coil structure”. The YOROI-coil structure consists of the upper and lower plates and the outer frame of the winding. The outer frame is connected to the upper and lower plates, and transfers a part of electromagnetic force from the coil winding to the reinforcing outer plates. However, to realize HTS magnets with higher magnetic field and higher current density, development of advanced YOROI-coil structure is expected. In this study, we investigated effect of stress control structure to realize HTS coil with a mechanical strength over 2GPa by the three-dimensional finite element structural analyses

  • Study on design of high-temperature superconducting magnet generating high field and high-accuracy field

    Project Year :

    2013.04
    -
    2016.03
     

     View Summary

    Toward the applications of REBCO superconducting coil to the high field magnets for NMR, MRI, accelerator and so on, the current distribution in REBCO winding were investigated by using the three-dimensional electromagnetic simulation. In these application, the magnets need to create highly homogeneous and temporally stable field. However, the screening currents lead to the serious problem in REBCO magnets for the applications required very high field quality. The reduction methods of screening current such as the overshoot method with transporting the current, the sequence of excitation in multiple REBCO coil, and the effect of screening current-induced field in copper-plated mutifilamentary REBCO tape were evaluated. This work contributes to the prediction and reduction of screening current-induced field and the design of high temperature superconducting magnet generating high field and high-accuracy field

  • Development of fundamental technology of next generation superconducting cyclotron for heavy particle cancer therapy

    Project Year :

    2011.04
    -
    2014.03
     

     View Summary

    Our objective is to develop an Advanced Hybrid Cyclotron (AHC) using High-Temperature Superconducting (HTS) coil technology with a compact body, high efficiency, and high performance in heavy particle cancer therapy. For cyclotron application, high accuracy magnetic field distribution with isochronous field and azimuthally varying field (AVF) are required. We proposed a coil system be composed of HTS air-core split coils for isochronous field and HTS air-core spiral sector coils for AVF. In this study, to realize the HTS coil system technology for AHC, we performed the following three issues: 1) optimal design of HTS coil system; 2) reduction of irregular magnetic field caused by coil winding error, deformation due to thermal and electromagnetic stress, and screening current induced in tape type superconductor such as Y-system coated conductor; and 3) Experiments on effects of irradiation on commercially available Bi-2223 and YBCO superconducting tapes

  • Fundamental studies on superconducting coil systemofheavy-ion accelerator for cancer therapy

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2008
    -
    2010
     

    ISHIYAMA Atsushi, YAMAKAWA Hiroshi, WAKAO Shinji, UEDA Hiroshi, MIYAHARA Nobuyuki

     View Summary

    Japan has a good track record in the heavy-ion radiotherapy which is a powerful method for cancer treatment. To expand this excellent therapeutic technique onto the world stage, the development of further reduced size, high-efficiency and low-cost accelerator. To realize the application of HTS (High Temperature Superconductor) coil to cyclotron system, we conducted preliminary experiments of the neutron irradiation to HTS tapes. And we made radioactive analyses on HTS tapes and measured the superconducting characteristics before and after the irradiation. We also performed a trial design of HTS coil for medical cyclotron system

  • Fundamental Studies on Characteristic Evaluation and Application of Bulk Superconductor

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2001
    -
    2003
     

    ISHIYAMA Atsushi, UEDA Hiroshi, TSUDA Makoto, WAKAO Shinji

     View Summary

    1.A new type of active-maglev system is designed and constructed using YBCO bulk and multiple electromagnets. And the continuous levitation was demonstrated with controlling the levitation height using three and five electromagnets systems and electromagnetic behavior within the bulk was investigated using a FEM computer program.2.A magnetic levitating device was proposed with two-dimensional movement, namely a 'levitating X-Y transporter'. For a real design of levitating X-Y transporter, the lift and the restoring force were examined experimentally and a simulation program was newly developed based on the three-dimensional hybrid FE-BE method to analyze the dynamic electromagnetic behaviors of the HTS bulk. Then the relationship between the various forces and distributions of supercurrent and magnetic field was clarified through experiments and numerical simulation. And the design of a levitating transporter was also performed.3.We fabricated and tested a linear synchronous actuator with double-sided primary and field-cooled YBCO bulk secondary. We experimentally investigated the static characteristic in points of synchronous torque, the starting thrust and the pull-in characteristics. And we developed a simulation program based on FEM to investigate electromagnetic behavior within the bulk exposed to the magnetic field generated by the primary winding.4.The transition of trapped field was experimentally investigated while applying external AC magnetic field with various amplitude and frequency to a disk-shaped YBCO bulk. And the numerical simulation was also performed using a newly developed computer program based on the FEM. The experiment of trapped field attenuation was carried out in long term applying field with a frequency of 50 Hz. The attenuation is abruptly large and finally the trapped field is disappeared. This means that shielding current distribution within the bulk is changed by the time-varying magnetic field and the transient magnetic flux movement results in temperature rise and finally the reduction of the trapped field

  • 光ネットワーク終端機器に対する太陽光無停電電源システムの研究開発プロジェクト

    文部科学省 

    Project Year :

    1999
    -
    2003
     

  • 環境共生型高精度エネルギー予測/高効率エネルギー利用技術

    文部科学省 

    Project Year :

    1998
    -
    2002
     

  • 太陽光自立電源システムの開発研究

    文部科学省 

    Project Year :

    1997
    -
    2001
     

  • Development of U-Shaped Linear Hybrid Motor

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    1999
    -
    2000
     

    ISHIYAMA Atsushi, WAKAO Shinji, IWAMOTO Shinichi

     View Summary

    The purpose of this research is to develop the linear induction - synchronous hybrid motor with a novel construction for practical use. In recent years, as for the adoption of the electric motors in the fields of industrial world, high stable alternating-current motor represented in the induction motor and the synchronous motor becomes the main stream. Though there are complementary relations between the induction motor and the synchronous motor in terms of advantages and disadvantages, it was difficult to hybridize them by existing structure because of the decline of the efficiency for operation. From the standpoint of the linear motors with construction, we proposed that the U-shaped linear hybrid motor that made us operate the induction motor in parallel with the synchronous motor on the same winding coil. A detailed examination was done for practical use.First as a fundamental investigation, we verified that the undesirable magnetic attraction was offset by its symmetrical construction, the space harmonics was reduced effectively by an adoption of split pole on the side of field winding with the concept of pulse width modulation, the effective inductive thrust for self starting and hunting prevention was obtained by hybridizing synchronous actions to the inductive actions.Furthermore, we investigated not only the static characteristics, but also the transient characteristics by the running experiment. As a consequence, we have succeeded to confirm the effectiveness of the proposed motor achieved to be synchronized with less vibration and shorter range.In future, it can be thought that the development of the linear hybrid motor including several characteristics proceed more.Since the characteristic ratio of each motor depends on the characteristics on the whole of the motor, as for getting requested characteristics with this hybrid motor, it is thought to be very effective that proposed motor has U-shaped construction which is independent on the secondary side part respectively

  • Evaluation of High Temperature Superconductors

    Project Year :

    1999
     
     
     

  • Stability of High Field and High Temperature SMES

    Project Year :

    1999
     
     
     

  • Study on Stability of Superconducting Cables for AC Application

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    1997
    -
    1999
     

    ISHIYAMA Atsushi, KIM Seokbeom, WAKAO Shinji, ONUKI Takashi

     View Summary

    1. Transient stability of multi-strand superconducting cablesWe developed a computer code based on 3D funite element method and a distributed circuit to simulate transient behaviors of three- strand superconducting cables such as temperature evolution in strand and cables, and current distribution among strands in quench process. Especially, we focused on the effect of cupper matrix on the transient stability. From these results obtained for the term of this project, the guideline for the design and development of highly stabilized superconducting cables for AC use.2. Development of superconducting cylindrical linear induction motorWe have designed and constructed a model cylindrical linear induction motor (SCLIM) with superconduting primary windings to clarify the behaviors (AC loss, stability and so on) of AC superconducting windings in a realistic operational environment of electrical rotating machines. The fundamental operational properties such as thrust characteristic and the electro-magnetic and mechanical phenomena in the superconducting windings were investigated. And we optimized the current distribution in primary windings to enhance the thrust characteristic and proposed a newly quench protection circuit for a realistic operation of superconducting electrical machines.3. Stability Criterion for Cryocooler-cooled HTS CoilsMagnet technology of high-temperature superconductor (HTS) with conduction cooling system by GM cryocooler have been advanced. We have measured the quench characteristics of HTS tapes (Bi-2223/Ag, Bi2212/Ag tapes) with conduction cooling system by GM cryocooler and developed a computer program based on the finite element to investigate the thermal and electromagnetic behaviors within HTS tapes. Using the simulation code, we discussed a stability criterion for cryocooler-cooled HTS coils. The current at which "thermal runaway" occurs, depends on the relationship between the cooling power of GM cryocooler and heat generation within HTS coils, is chosen as a stability criterion. We also investigate the transient thermal and electromagnetic behaviors in HTS coils during a quench process to determine the thermal and current margin in a realistic operation

  • Basic Study on Application of Superconductivity to AC use

    Project Year :

    1994
    -
    1998
     

  • Study on transient stability of superconducting cables

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    1994
    -
    1996
     

    ISHIYAMA Atsushi, SEOKBEOM Kim, TSUDA Makoto, WAKAO Shinji, ONUKI Takashi

     View Summary

    19941. Numerical cord for simulation of transient stability of multi-strand superconducting cables : We developed some computer codes to simulate transient behaviors of multi-strant cables such as current distribution among srands and temperature distribution in cables. We also developed a method for estimation of the current distribution among strands by using a pick-up coil system.2. Sensitive method for measurement of electrical cross contact resistance between strands : We proposed a new method adopting superconducting transformer. By this method, we could measure small cross contact resistance of about 10^<-8> OMEGA.19951. Simulation of transition to normal state in multi-strand superconducting cables : We carried out a lot of experiments to evaluate the validity of the developod computer codes and to investigate the transient behavior of multi-strand cables in quench process. From these numerical simulations and experimental results, the influences of the material properties of superconduciting strand and the thermal effect of coolant on the transient stability became evident.2. Measurement of cross contact resistance of Rutherford type cables : We adopted the proposed method to measure the cross contact resistance of Rutherford cables for SSC project.19961. Simulation of transition to normal state in multi-strand superconducting cables : We newly developed a computer code by 3D finite element analysis to investigate the temperature evolution in cross-section of a strand and to clarify the effect of copper matrix on the transient stability. From these results obtained for the term of this project, the guideline for the design and development of highly stabilized superconducting cables for AC use.2. Measurement of cross contact resistance of Rutherford type cables : We investigated the influences of curing temperature and pressure on the cross contact resistance of Ratherford cables

  • Development of analysis method for calculating electromagnetic force using finite element method and boundary element method in electrical machinery

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    1994
    -
    1996
     

    ONUKI Takashi, WAKAO Shinji, ISHIYAMA Atsushi

     View Summary

    The use of computer software for the design of electrical machinery is now almost universal. The finite element method (FEM) and the boundary element method (BEM), which have entirely different features from each other, are very useful for computer numerical analysis. In the analysis of general motor, the FEM suits the analysis of a complicated region which includes teeth, slots, and magnets, and so on. On the other hand, the BEM is useful for analyzing the electromagnetic quantities caused by rotation without remeshing in the FEM.The hybrid finite element and boundary element method (FE-BE) method that possess the advantages in these methods is also useful.In this research, we first investigated several basic study for accurate analysis by FEM,BEM,and FE-BE method. And than, taking account of the advantages in both methods, we apply the hybrid FE-BE method to the analyzes of several electrical machines, which are researching in our laboratory : linear induction motor (LIM), linear synchronous motor (LSM), and permanent magnet type synchronous motor (PMSM) having plural sub-magnets for one pole. By investigating the characteristics of the motors, we could obtain some optimal motor constructions. In addition, taking account of external voltage sources, we also derived an optimal block feeding conditions in single-sided LIM.The adequacy of the analysis results were confirmed by experiment

  • 3D Eddy Current Analysis by the Hybrid FE-BE Method Using Magnetic Field Intensity

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    1991
    -
    1993
     

    ONUKI Takashi, ISHIYAMA Atsushi

     View Summary

    The use of computer software for the design of electromagnetic devices is now almost universal. The phenomena in electromagnetic fields, which are central to many aspects of electro magnetic machines, intrinsically spread over the infinite space. We sometimes have to consider the infinite region rigorously, e.g. for estimating the mangetic field made by superconduting magnets. The purpose of this research is to provide a useful method for the numerical calculation of electromagnetic field with open boundary, and particular attention is given to the 3-D eddy current problems. The finite element method (FEM) and the boundary element method (BEM), which have entirely different features from each other, are very useful for numerical analysis. Both methods seem to be complementary partners and not opponents. The FEM suits for the analysis of such a coplicated region which includes no-linear materials. However, it has some disadvantages in dealing with the infinitely extending fields. On the other hand, the BEM is useful for analyzing very large linear fields. Therefore taking account of the advantages in these methods, this research is concerned with the hybrid finite element and boundary element (FE-BE) method for the 3-D eddy current analysis. Both the FEM and the BEM can adopt various kinds of physical quantities as unknowns, so ther are many ways to combine both methods. Inthis research we have proposed several hybrid formulations in which some kinds of physical quantities are adopted as unknowns. The advantages and disadvantages of respective hybrid methods are examined. The appropriate boundary element discretization using edge elements is also developed, which is suitable for combining the FE region with the BE region. The approaches proposed in this research are always verified by concrete munerical examples

  • Study on Thermal and Electromagnetic Properties of Superconducting Wires for AC Use

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    1990
    -
    1992
     

    ISHIYAMA Atsushi, ONUKI Takashi

     View Summary

    Superconducting wires with a CuNi matrix for a.c. applications are not fully stabilized and normal transition is easily induced by various disturbances because the CuNi matrix has a high electrical resistivity and a very low thermal conductivity comparing with the properties of copper. Therefore, the thermal and the electromagnetic behavior of such wires during quench is apparently different from that of conventional copper-stabilized composites. To investigate these properties, we consider the effects of temperature gradient in radial direction of wire cross-section and the redistribution of currents at normal front. We measured longitudinal normal-zone propagation velocities of NbTi/CuNi composites wires which have different cooling condition and compared them with analytical results by the three-dimensional finite element method taking into account the redistribution of currents; influence of the transverse electrical conductance on the current sharing in a composite. The analytical results agree well with experiments. And in a.c. use of superconductivity we also need to know the thermal and electromagnetic behaviors during such abrupt increase of transport currents as short-circuit current in superconducting transformers, current changing in super-conducting current limiters and current redistribution during quench process in multi-strand cables. We measured the quench current of NbTi/CuNi superconducting wires as a function of a external d.c. magnetic field, the current sweep rate in the range of 10A/s to 100KA/s and the initial current, which is a transport current just before current changing. Experimental data is compared with analytical results by the finite element method taking the magnetic and the thermal diffusion in radial direction of wire cross-section into account. From these results, the mechanism of normal-zone propagation, the quench current degradation and influence of these phenomena on the abnormal quench process with apparent high normal-zone propagation velocity in multi-strand superconducting cables were discussed

  • Three-Dimensional Eddy Current Analysis by Hybrid Finite Element and Boundary Element Method

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    1988
    -
    1990
     

    ONUKI Takashi, YOKOI Toshiaki, ISHIYAMA Atasushi

     View Summary

    We have been developing the Hybrid Finite Element and Boundary Element Method for three-dimensional electromagnetic field analysis includes eddy current calculation. Among various electromagnetic quantities, the magnetic vector potential A and the electric scalar potential phi are widely used for the eddy current analysis. This approach is known as the A-phi method. We adopts the quantities A-phi in both the boundary element method and the finite element method. For some problems, it is very complicated to complicated to combine boundary conditions of the boundary element method with those of the usual finite element method. To avoid this difficulty, we have developed a novel boundary element formulation using magnetic potential.Although the A-phi method is theoretically satisfactory, we need four variables for each node in three-dimensional analysis. In order to reduce the number of unknown variables, we proposed the adoption of the magnetic field intensity H and the magnetic scalar potential psi in the hybrid method.We applied the proposed method to the real electric apparatus ; linear induction motor, magnetic levitation system, hyperthermia and superconducting magnet system.We also developed a novel optimal design method for electromagnetic fields. The optimal design method is based on a combination of the hybrid finite element and boundary element method for electromagnetic field calculation and the mathematical programming method for solving corresponding optimization problem. Application of the optimal design method to practical examples ; superconducting magnet system with magnetic shielding for Magnetic Resonance Imaging and hybrid magnet for magnetic levitation system, gave satisfying results

  • 超電導交流機器における超電導巻線の冷却特性および常電導伝播特性に関する研究

    日本学術振興会  科学研究費助成事業

    Project Year :

    1989
     
     
     

    石山 敦士

  • 有限・境界要素法と数理計画法の併用による電気機器の最適設計に関する研究

    日本学術振興会  科学研究費助成事業

    Project Year :

    1986
     
     
     

    石山 敦士

▼display all

Misc

  • MAGNETIC FIELD DESIGN OF VARIABLE-BEAM-TYPE SKELETON CYCLOYTRON

    CHONG Tsun Him, 福田光宏, 依田哲彦, 神田浩樹, 斎藤高嶺, 安田祐介, 原隆文, ZHAO Hang, 橘高正樹, 松井昇太朗, 渡辺薫, 井村友紀, 石山敦士, 野口聡, 植田浩士, 吉田潤, 長屋重夫, 渡部智則

    日本加速器学会年会(Web)   20th  2023

    J-GLOBAL

  • DESIGN AND ORBIT CALCULATION OF THE HIGH-TEMPERATURE SUPERCONDUCTING SELF-SHIELDING TYPE SKELETON CYCLOTRON

    松井昇大朗, 福田光宏, 依田哲彦, 神田浩樹, 齋藤高嶺, 田村仁志, 安田裕介, 長屋重夫, 原隆文, CHONG Tsun Him, ZHAO Hang, 橘高正樹, 井村友紀, 渡辺薫, 石山敦士, 野口聡, 植田浩史, 福井聡, 松原雄二, 三上行雄, 吉田潤, 平山貴士, 渡辺智則

    日本加速器学会年会(Web)   20th  2023

    J-GLOBAL

  • Energization Waveform for Reducing Screening Current-Induced Magnetic Field in Multi-Stacked No-Insulation REBCO Coil Systems

    吉藤夢来, 日比祐太, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM)   2023  2023

    J-GLOBAL

  • Development of REBCO coil system for Skeleton Cyclotron: Fabrication of a small demonstration REBCO coil system

    折原菜月, 熊谷塁, 糸日谷浩平, 小久保早希, 石山敦士, 植田浩史, 野口聡, 福田光宏

    電気学会全国大会講演論文集(CD-ROM)   2023  2023

    J-GLOBAL

  • Screening current-induced magnetic field analysis of No-Insulation coils using bidirectional split-circuit

    島田亜緒, 小久保早希, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM)   2023  2023

    J-GLOBAL

  • Screening current-induced magnetic field analysis of no-insulation REBCO coils based on only equivalent circuit model

    吉藤夢来, 内山誠士郎, 太田海斗, 石山敦士, 野口聡, 植田浩史

    電気学会研究会資料(Web)   ( ASC-23-001-014.016 )  2023

    J-GLOBAL

  • Evaluation of excitation characteristics of no-insulation REBCO coils based only on the equivalent circuit model

    島田亜緒, 内山誠士郎, 太田海斗, 石山敦士, 野口聡, 植田浩史

    電気学会研究会資料(Web)   ( ASC-23-001-014.016 )  2023

    J-GLOBAL

  • Screening current-induced magnetic field analysis of no-insulation REBCO coils based on only equivalent circuit model

    吉藤夢来, 内山誠士郎, 太田海斗, 石山敦士, 野口聡, 植田浩史

    低温工学・超電導学会講演概要集   105th  2023

    J-GLOBAL

  • Development of REBCO coil system for Skeleton Cyclotron (Spring 2023): (Part 1) Overview

    石山敦士, 熊谷塁, 野口聡, 植田浩史, 渡部智則, 吉田潤, 福田光宏, 長屋重夫

    低温工学・超電導学会講演概要集   105th  2023

    J-GLOBAL

  • Development of REBCO coil system for Skeleton Cyclotron (Spring 2023): (Part 4) Strain estimation of 1/2 scale demonstration REBCO coil system

    植田浩史, 山下葵, 小前諒太, 井上良太, KIM SeokBeom, 石山敦士, 熊谷塁, 野口聡, 渡部智則, 吉田潤, 福田光宏, 西島元

    低温工学・超電導学会講演概要集   105th  2023

    J-GLOBAL

  • Thermal stability evaluation of a REBCO coil system for the ′′Skeleton Cyclotron′′

    日浦琢言, 中村太郎, 天野一樹, 寺内和, 石山敦士, 野口聡, 植田浩史

    低温工学・超電導学会講演概要集   105th  2023

    J-GLOBAL

  • Development of REBCO coil system for Skeleton Cyclotron (Spring 2023): (Part 5) Development of NI-REBCO coil for ECR Ion Source

    CHONG Tsun Him, 福田光宏, 石山敦士, 植田浩史, 野口聡, 福井聡, 吉田潤, 渡部智則

    低温工学・超電導学会講演概要集   105th  2023

    J-GLOBAL

  • Screening current-induced magnetic field analysis of No-Insulation coils which uses bidirectional split-circuit screening current magnetic field analysis (Part 2): Formulation

    内山誠士郎, 小久保早希, 石山敦士, 植田浩史, 野口聡

    低温工学・超電導学会講演概要集   104th  2022

    J-GLOBAL

  • Screening current-induced magnetic field analysis of No-Insulation coils which uses bidirectional split-circuit screening current magnetic field analysis (Part 1): Formulation

    太田海斗, 小久保早希, 石山敦士, 植田浩史, 野口聡

    低温工学・超電導学会講演概要集   104th  2022

    J-GLOBAL

  • Thermal stability of No-Insulation REBCO Multi-coil assuming a skeleton cyclotron

    中村太郎, 長渕大河, 結城拓真, 濱田一希, 石山敦士, 野口聡, 植田浩史

    低温工学・超電導学会講演概要集   104th  2022

    J-GLOBAL

  • Development of REBCO coil system for Skeleton Cyclotron: Manufacturing of a small demonstration REBCO coil system

    熊谷塁, 糸日谷浩平, 小久保早希, 石山敦士, 植田浩史, 野口聡, 福田光宏

    低温工学・超電導学会講演概要集   104th  2022

    J-GLOBAL

  • Energization waveform for reducing Screening Current-induced Magnetic Field in Multi-stacked No-Insulation REBCO Coil Systems

    内山誠士郎, 村上将吾, 小久保早希, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM)   2022  2022

    J-GLOBAL

  • Improvement of Temporal Stability by Current Control in High Temperature Superconducting Skeleton Cyclotron

    熊谷塁, 白井航大, 石山敦士, 植田浩史, 野口聡, 渡部智則, 長屋重夫, 福田光宏

    電気学会全国大会講演論文集(CD-ROM)   2022  2022

    J-GLOBAL

  • Adequacy evaluation of screening current-induced magnetic field analysis which uses radial division analysis

    太田海斗, 小久保早希, 白井航大, 石山敦士, 植田浩史, 野口総

    電気学会全国大会講演論文集(CD-ROM)   2022  2022

    J-GLOBAL

  • Fundamental investigation of monitoring method for detecting the state of health of no-insulation REBCO coils with defects

    寺内和, 結城拓真, 長渕大河, 濱田一希, 石山敦士, 野口聡, 植田浩史

    低温工学・超電導学会講演概要集   103rd  2022

    J-GLOBAL

  • Adequacy evaluation of screening current-induced magnetic field analysis which uses radial division analysis

    太田海斗, 小久保早希, 石山敦士, 植田浩史, 野口聡

    低温工学・超電導学会講演概要集   103rd  2022

    J-GLOBAL

  • Possibility of continuous operation of Multi-Stacked No-Insulation REBCO Pancake Coil System with a local defect

    中村太郎, 長渕大河, 結城拓真, 濱田一希, 石山敦士, 野口聡, 植田浩史

    低温工学・超電導学会講演概要集   103rd  2022

    J-GLOBAL

  • Development of REBCO coil system for Skeleton Cyclotron (Part 3): Design of real-scale coil system

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    低温工学・超電導学会講演概要集   101st  2021

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  • Examination on reduction of screening current-induced magnetic field by current control method for REBCO coil system of Skelton Cyclotron

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    糸日谷浩平, 白井航大, 石山敦士, 植田浩史, 野口聡, 渡部智則, 長屋重夫, 福田光宏

    電気学会全国大会講演論文集(CD-ROM)   2021  2021

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  • Reduction Method of screening current-induced magnetic field considering charging delay in No-Insulated REBCO coil system

    小久保早希, 村上将吾, 石山敦士, 植田浩史, 野口聡

    電気学会研究会資料(Web)   ( MC-21-001-008/ASC-21-001-008 )  2021

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    白井航大, 緒方隆充, 稲垣善太, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM)   2020  2020

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    村上将吾, 稲垣善太, 上田聡美, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM)   2020  2020

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    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM)   71st  2020

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    低温工学・超電導学会講演概要集   100th  2020

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    村上将吾, 上田聡美, 石山敦士, 植田浩史, 野口聡

    低温工学・超電導学会講演概要集   100th  2020

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    低温工学・超電導学会講演概要集   100th  2020

    J-GLOBAL

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    低温工学・超電導学会講演概要集   98th   79  2019.05

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    低温工学・超電導学会講演概要集   98th   123  2019.05

    J-GLOBAL

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    低温工学・超電導学会講演概要集   98th   80  2019.05

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    低温工学・超電導学会講演概要集   98th   78  2019.05

    J-GLOBAL

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    石崎比奈子, 上田聡美, 稲垣善太, 石山敦士, 植田浩史, 野口聡

    低温工学・超電導学会講演概要集   98th   121  2019.05

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    低温工学・超電導学会講演概要集   98th   122  2019.05

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    低温工学・超電導学会講演概要集   98th   77  2019.05

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    電気学会全国大会講演論文集(CD-ROM)   2019   ROMBUNNO.5‐169  2019.03

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    石崎比奈子, 稲垣善太, 伊東慶太, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM)   2019   ROMBUNNO.5‐171  2019.03

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  • MRI用REBCOコイルシステムにおける遮蔽電流に起因する不整磁場の低減法(その2):細線化と電流制御の併用法の最適化

    緒方隆充, 稲垣善太, 伊東慶太, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM)   2019   ROMBUNNO.5‐170  2019.03

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    電気学会全国大会講演論文集(CD-ROM)   2019   ROMBUNNO.5‐172  2019.03

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    電気・情報関連学会中国支部連合大会講演論文集(CD-ROM)   70th  2019

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    低温工学・超電導学会講演概要集   97th   80  2018.11

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    低温工学・超電導学会講演概要集   97th   88  2018.11

    J-GLOBAL

  • 欠陥のあるREBCO線材で巻線した無絶縁パンケーキコイルの電磁的・熱的特性解析・評価

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    低温工学・超電導学会講演概要集   97th   95  2018.11

    J-GLOBAL

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    野口聡, 野口聡, 立田貴裕, 植田浩史, KIM Seokbeom, 石山敦士

    低温工学・超電導学会講演概要集   97th   98  2018.11

    J-GLOBAL

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    低温工学・超電導学会講演概要集   97th   79  2018.11

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    低温工学・超電導学会講演概要集   96th   51  2018.05

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    低温工学・超電導学会講演概要集   96th   52  2018.05

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    低温工学・超電導学会講演概要集   96th   71  2018.05

    J-GLOBAL

  • 高強度小型多機能スケルトンサイクロトロンの開発―超電導コイル設計―

    野口聡, 植田浩史, 石山敦士, 渡部智則, 長屋重夫, 吉田潤, 鶴留武尚, 高橋伸明, 三上行雄, 福田光宏

    低温工学・超電導学会講演概要集   96th   79  2018.05

    J-GLOBAL

  • 高強度小型多機能スケルトンサイクロトロンの開発―遮蔽電流磁場解析―

    粟津佑太, KIM SeokBeom, 植田浩史, 野口聡, 石山敦士, 渡部智則, 長屋重夫, 吉田潤, 鶴留武尚, 高橋伸明, 三上行雄, 福田光宏

    低温工学・超電導学会講演概要集   96th   78  2018.05

    J-GLOBAL

  • サイクロトロン用高温超電導マグネットの遮蔽電流磁場評価

    粟津佑太, KIM Seok Beom, 植田浩史, 野口聡, 石山敦士, 渡部智則, 長屋重夫, 吉田潤, 鶴留武尚, 高橋伸明, 三上行雄, 福田光宏

    電気学会全国大会講演論文集(CD-ROM)   2018   ROMBUNNO.5‐160  2018.03

    J-GLOBAL

  • 9.4T‐MRIにおけるREBCO線材の細線化による遮蔽電流磁場への影響の解析

    稲垣善太, 伊東慶太, 小曽根裕一, 石山敦士, 植田浩史, 野口聡

    電気学会全国大会講演論文集(CD-ROM)   2018   ROMBUNNO.5‐161  2018.03

    J-GLOBAL

  • Research and Development of a High-field Coil System

    Hiroshi MIYAZAKI, Sadanori IWAI, Taizo TOSAKA, Shunji NOMURA, Tsutomu KURUSU, Hiroshi UEDA, So NOGUCHI, Atsushi ISHIYAMA, Shinichi URAYAMA, Hidenao FUKUYAMA

    TEION KOGAKU (Journal of Cryogenics and Superconductivity Society of Japan)   52 ( 4 ) 224 - 233  2017.07  [Refereed]  [Invited]

     View Summary

    &lt;p&gt;A project for developing of RE&lt;sub&gt;1&lt;/sub&gt;Ba&lt;sub&gt;2&lt;/sub&gt;Cu&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;7-&amp;delta;&lt;/sub&gt; (REBCO) magnets to be utilized in ultrahigh-field magnetic resonance imaging (MRI) was started in 2013. Our final targets are 9.4 T MRI systems for whole-body and brain imaging. In this project, two different development approaches towards the final target were planned. One is a small REBCO coil that can generate 10 Tclass magnetic fields, which is the same level as the target magnetic field. The other is a conduction-cooled 1.5 T REBCO MRI magnet that has a room-temperature bore of 396 mm, which is as large as those of mid-sized model magnets. These results were reflected in the design of a conduction-cooled 9.4 T REBCO magnet for whole-body MRI systems.&lt;/p&gt;

    DOI CiNii J-GLOBAL

  • Research and Development of a High-field Coil System:– Development of a high-temperature superconducting magnet for ultrahigh-field MRI –

    MIYAZAKI Hiroshi, FUKUYAMA Hidenao, IWAI Sadanori, TOSAKA Taizo, NOMURA Shunji, KURUSU Tsutomu, UEDA Hiroshi, NOGUCHI So, ISHIYAMA Atsushi, URAYAMA Shinichi

    TEION KOGAKU (Journal of Cryogenics and Superconductivity Society of Japan)   52 ( 4 ) 224 - 233  2017.07  [Refereed]  [Invited]

     View Summary

    <p>A project for developing of RE1Ba2Cu3O7-&delta; (REBCO) magnets to be utilized in ultrahigh-field magnetic resonance imaging (MRI) was started in 2013. Our final targets are 9.4 T MRI systems for whole-body and brain imaging. In this project, two different development approaches towards the final target were planned. One is a small REBCO coil that can generate 10 Tclass magnetic fields, which is the same level as the target magnetic field. The other is a conduction-cooled 1.5 T REBCO MRI magnet that has a room-temperature bore of 396 mm, which is as large as those of mid-sized model magnets. These results were reflected in the design of a conduction-cooled 9.4 T REBCO magnet for whole-body MRI systems.</p>

    DOI CiNii

  • 銅メッキ付き多芯REBCO線材における遮蔽電流による不整磁場の低減効果

    武藤優真, 石山敦士, 小泉智暉, 植田浩史, KIM Seok Beom, 野口聡

    低温工学・超電導学会講演概要集   94th   7  2017.05

    J-GLOBAL

  • 9.4T級ヒト全身用MRI用コイルにおける遮蔽電流による不整磁場の解析・評価

    伊東慶太, 石山敦士, 植田浩史, 野口聡, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集   94th   133  2017.05

    J-GLOBAL

  • ML‐MI REBCOパンケーキコイルにおける層間電気抵抗の調整実験

    市川哲理, 矢代聡佳, ZHENG Qiyi, 柿本雄太, 石山敦士, 野口聡

    低温工学・超電導学会講演概要集   94th   170  2017.05

    J-GLOBAL

  • 超電導線接続箇所を有する無絶縁REBCOパンケーキコイルの熱的安定性評価

    柿本雄太, ZHENG Qiyi, 矢代聡佳, 市川哲理, 石山敦士, 野口聡, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集   94th   135  2017.05

    J-GLOBAL

  • REBCOパンケーキコイルの遮蔽電流磁場簡易計算法

    宮尾亮介, 植田浩史, 石山敦士, HAHN Seungyoung, 野口聡

    低温工学・超電導学会講演概要集   94th   9  2017.05

    J-GLOBAL

  • 無絶縁REBCOパンケーキコイルにおける層間接触電気抵抗の調整に関する検討

    市川哲理, 勝俣一輝, 矢代聡佳, ZHENG Qiyi, 石山敦士, 野口聡, 渡部智則, 長屋重夫

    電気学会全国大会講演論文集(CD-ROM)   2017   ROMBUNNO.5‐112  2017.03

    J-GLOBAL

  • 9.4T級ヒト全身用MRI用コイルにおける遮蔽電流による不整磁場の解析

    伊東慶太, 中園浩平, 石山敦士, 植田浩史, 野口聡, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努, 浦山慎一, 福山秀直

    電気学会全国大会講演論文集(CD-ROM)   2017   ROMBUNNO.5‐115  2017.03

    J-GLOBAL

  • 複数の超電導線接続箇所を有する無絶縁REBCOコイルの熱的安定性評価

    柿本雄太, 勝俣一輝, ZHENG Qiyi, 矢代聡佳, WANG Tao, 石山敦士, 野口聡, 長屋重夫, 渡部智則

    電気学会全国大会講演論文集(CD-ROM)   2017   ROMBUNNO.5‐111  2017.03

    J-GLOBAL

  • REBCO線材における細線化による遮蔽電流に起因する不整磁場の低減効果

    武藤優真, 中園浩平, 小曽根裕一, 石山敦士, 植田浩史

    電気学会全国大会講演論文集(CD-ROM)   2017  2017

    J-GLOBAL

  • 銅メッキ付き多芯REBCOテープ線材で巻線された高温超電導コイルの遮蔽電流評価実験と解析

    植田浩史, 石山敦士, 柳澤吉紀, 前田秀明

    低温工学・超電導学会講演概要集   94th  2017

    J-GLOBAL

  • REBCOコイルにおける細線化処理による遮蔽電流不整磁場低減効果の解析:9.4T級ヒト全身用MRIコイルを対象として

    伊東慶太, 石山敦士, 植田浩史, 野口聡

    低温工学・超電導学会講演概要集   95th  2017

    J-GLOBAL

  • An accelerated computation method of Legendre polynomial coefficients for MRI REBCO magnet design

    Noguchi, So, Noguchi, So, Miyao, Ryosuke, Igarashi, Hajime, Ishiyama, Atsushi

    IEEE CEFC 2016 - 17th Biennial Conference on Electromagnetic Field Computation    2017.01

     View Summary

    © 2016 IEEE.When designing an MRI magnet, its field homogeneity is evaluated by higher-order coefficients of the Legendre polynomial expression than 0th. Recently, the development of ultra-high-field (∼10 T) MRI magnet wound with REBCO tapes is underway. REBCO tapes are flat, and its current-carrying region is very narrow compared to its cross section. However, to compute the higher-order coefficients for MRI REBCO magnet is a labor task because the current-carrying region is discretely arranged. In this paper, we propose an accelerated method of computing the higher-order coefficients of the Legendre polynomials for MRI REBCO magnet design using a shift operator.

    DOI

  • SQUIDによるラット心磁図への統計解析を用いた肺動脈性肺高血圧症検出法 (超伝導エレクトロニクス)

    安田 昌太郎, 日向野 将, 小野 弓絵, 梶村 いちげ, 南沢 享, 石山 敦士

    電子情報通信学会技術研究報告 = IEICE technical report : 信学技報   116 ( 175 ) 87 - 92  2016.08

    CiNii

  • HTS-SQUIDを用いたラット心磁図計測の有用性の検討 (超伝導エレクトロニクス)

    日向野 将, 安田 昌太郎, 石山 敦士, 小野 弓絵, 廿日出 好

    電子情報通信学会技術研究報告 = IEICE technical report : 信学技報   116 ( 175 ) 81 - 86  2016.08

    CiNii

  • Reduction technique of Irregular Magnetic Field Distribution Generated by Screening Current in REBCO Multiple Coils

    小曽根 裕一, 中園 浩平, 王 韜, 石山 敦士, 植田 浩史, 野口 聡, 宮崎 寛史, 戸坂 泰造, 野村 俊自, 来栖 努

    電気学会研究会資料. MC   2016 ( 13 ) 43 - 47  2016.06

    CiNii J-GLOBAL

  • Development of an HTS magnet for ultra-high field MRI

    宮崎 寛史, 岩井 貞憲, 戸坂 泰造, 野村 俊自, 来栖 努, 植田 浩史, 野口 聡, 石山 敦士, 浦山 慎一, 福山 秀直

    電気学会研究会資料. MC   2016 ( 13 ) 49 - 51  2016.06

    CiNii J-GLOBAL

  • 高磁場MRI用高温超電導磁石の開発(‘16年春)―9.4Tヒト全身用MRIコイルの最適化設計と不整磁場評価―

    植田浩史, 植田浩史, 野口聡, 野口聡, 石山敦士, 岩井貞憲, 戸坂泰造, 宮崎寛史, 野村俊自, 来栖努, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集   93rd   5  2016.05

    J-GLOBAL

  • 高磁場MRI用高温超電導磁石の開発(16年春)―工業製品化を前提とするMRI用REBCOコイルシステムの開発―

    石山敦士, 植田浩史, 植田浩史, 野口聡, 野口聡, 浦山慎一, 福山秀直, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集   93rd   6  2016.05

    J-GLOBAL

  • PEECモデルによる無絶縁REBCOダブルパンケーキコイルにおける局所常電導転移発生時の電流分布解析

    宮尾亮介, 野口聡, 石山敦士

    低温工学・超電導学会講演概要集   93rd   13  2016.05

    J-GLOBAL

  • 高磁場MRI用高温超電導磁石の開発(16年春)―9.4T高温超電導MRI磁石設計―

    宮崎寛史, 岩井貞憲, 宇都達郎, 大谷安見, 戸坂泰造, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 植田浩史, 野口聡, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集   93rd   3  2016.05

    J-GLOBAL

  • 高磁場MRI用高温超電導磁石の開発(16年春)―全体概要―

    戸坂泰造, 宮崎寛史, 岩井貞憲, 宇都達郎, 大谷安見, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 植田浩史, 野口聡, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集   93rd   1  2016.05

    J-GLOBAL

  • (50T・500A/mm2・5GPa)‐REBCO超電導コイルシステムの開発

    石山敦士, 我妻洸, 齋藤隆, 野口聡, 植田浩史, KIM SeokBeom, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集   93rd   114  2016.05

    J-GLOBAL

  • 高磁場MRI用高温超電導磁石の開発(16年春)―REBCOマルチコイルにおける遮蔽電流による不整磁場の低減法―

    小曽根裕一, WANG Tao, 石山敦士, 植田浩史, 野口聡, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集   93rd   4  2016.05

    J-GLOBAL

  • 高磁場MRI用高温超電導磁石の開発(16年春)―伝導冷却1.5T‐MRI磁石の試験結果―

    宮崎寛史, 岩井貞憲, 宇都達郎, 大谷安見, 戸坂泰造, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 植田浩史, 野口聡, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集   93rd   2  2016.05

    J-GLOBAL

  • PEECモデルを用いた無絶縁REBCOダブルパンケーキコイルにおける局所常電導転移発生時に関する数値シミュレーション

    宮尾亮介, 門馬克敏, 野口聡, 石山敦士

    電気学会全国大会講演論文集(CD-ROM)   2016   ROMBUNNO.5‐094  2016.03

    J-GLOBAL

  • 9.4Tヒト全身用MRIコイルにおける遮蔽電流による不整磁場と磁場均一度の評価

    中園浩平, 松見絢子, WANG Tao, 石山敦士, 植田浩史, 野口聡, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努, 浦山慎一, 福山秀直

    電気学会超電導機器研究会資料   ASC-16 ( 1-12 ) 1‐6 - 6  2016.02

    CiNii J-GLOBAL

  • 10T級MRI用高温超電導磁石の開発-REBCOマルチコイルにおける遮蔽電流による不整磁場の評価試験と解析-

    小曽根裕一, 持田歩, WANG Tao, 石山敦士, 植田浩史, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    電気学会全国大会講演論文集(CD-ROM)   2016  2016

    J-GLOBAL

  • 高磁場MRI用高温超電導磁石開発の進捗(15年秋)―伝導冷却1.5T‐MRI磁石の開発―

    宮崎寛史, 岩井貞憲, 宇都達郎, 大谷安見, 戸坂泰造, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 植田浩史, 野口聡, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集   92nd   185  2015.12

    J-GLOBAL

  • 高磁場MRI用高温超電導磁石開発の進捗(15年秋)―極小口径10Tコイルの開発―

    岩井貞憲, 宮崎寛史, 大谷安見, 宇都達郎, 戸坂泰造, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 植田浩史, 野口聡, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集   92nd   184  2015.12

    J-GLOBAL

  • 2次元有限要素法を用いた無絶縁超電導コイルのターン間電流経路解析

    川口浩平, 門馬克敏, 野口聡, 石山敦士

    低温工学・超電導学会講演概要集   92nd   94  2015.12

    J-GLOBAL

  • 高磁場MRI用高温超電導磁石開発の進捗(15年秋)―進捗概要―

    戸坂泰造, 宮崎寛史, 岩井貞憲, 宇都達郎, 大谷安見, 高橋政彦, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 植田浩史, 野口聡, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集   92nd   183  2015.12

    J-GLOBAL

  • 高磁場MRI用高温超電導磁石開発の進捗(15年秋)9.4Tヒト全身用MRIコイルにおける遮蔽電流による不整磁場と磁場均一度の評価

    松見絢子, WANG Tao, 石山敦士, 植田浩史, 野口聡, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集   92nd   186  2015.12

    J-GLOBAL

  • ラット心磁図の逆問題解析を用いた肺動脈性肺高血圧症の早期検出

    安田 昌太郎, 日向野 将, 石山 敦士, 小野 弓絵, 梶村 いちげ, 南沢 享

    日本生体磁気学会誌   28 ( 1 ) 186 - 187  2015.06

  • 高磁場MRI用高温超電導磁石開発の進捗(15年春)―1/2サイズコイル試験―

    宮崎寛史, 岩井貞憲, 大谷安見, 高橋政彦, 戸坂泰造, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集   91st   148  2015.05

    J-GLOBAL

  • 高磁場MRI用高温超電導磁石開発の進捗(15年春)―均一磁場コイル最適化設計―

    野口聡, 石山敦士, 植田浩史, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集   91st   151  2015.05

    J-GLOBAL

  • 高磁場MRI用高温超電導磁石開発の進捗(15年春)―プロジェクト進捗概要―

    戸坂泰造, 宮崎寛史, 岩井貞憲, 大谷安見, 高橋政彦, 田崎賢司, 野村俊自, 来栖努, 石山敦士, 植田浩史, 野口聡, 浦山慎一, 福山秀直

    低温工学・超電導学会講演概要集   91st   147  2015.05

    J-GLOBAL

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  • REBCOコイルにおける遮蔽電流による不整磁場の低減

    今市洋平, 松見絢子, 持田歩, 有谷有汰, 齋藤隼, WANG Tao, 石山敦士, 植田浩史, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集   90th  2014

    J-GLOBAL

  • REBCO線材の超電導特性のばらつきが遮蔽電流磁場に与える影響

    松見絢子, 今市洋平, 持田歩, 有谷友汰, 齋藤隼, WANG Tao, 石山敦士, 植田浩史, 宮崎寛史, 戸坂泰造, 野村俊自, 来栖努

    低温工学・超電導学会講演概要集   90th  2014

    J-GLOBAL

  • 高温超伝導コイルを用いたスケルトン・サイクロトロン電磁石の設計研究

    FUKUDA MITSUHIRO, UEDA HIROSHI, HATANAKA KICHIJI, YORITA TETSUHIKO, ISHIYAMA ATSUSHI, WANG XUDONG, NAGAYA SHIGEO, WATANABE TOMONORI, NOGUCHI SATOSHI, YOKOTA WATARU, KURASHIMA SATOSHI, MIYAWAKI NOBUMASA

    日本加速器学会年会(Web)   11th   WEB ONLY SUOL05  2014

    J-GLOBAL

  • No‐Insulation REBCOパンケーキコイルの層間接触抵抗評価実験

    中田恵理香, 荒川一誠, 南克彦, 増井裕太, WANG Tao, WANG Xudong, 石山敦士, 野口聡, 渡部智則, 長屋重夫, HAHN Seungyong, IWASA Yukikazu

    低温工学・超電導学会講演概要集   88th   141  2013.12

    J-GLOBAL

  • No‐Insulation REBCOパンケーキコイルの励磁特性に関する実験と簡易解析

    荒川一誠, 南克彦, 中田恵理香, 増井裕太, WANG Tao, WANG Xudong, 石山敦士, 野口聡, HAHN Seungyong, IWASA Yukikazu

    低温工学・超電導学会講演概要集   88th   6  2013.12

    J-GLOBAL

  • No‐insulation ReBCOコイルのターン間接触抵抗の影響についての数値シミュレーションによる検討

    野口聡, 伊藤竜誠, WANG Tao, WANG Xudong, 石山敦士, HAHN Seungyong, IWASA Yukikazu

    低温工学・超電導学会講演概要集   88th   5  2013.12

    J-GLOBAL

  • YBCOパンケーキコイルにおける遮へい電流磁場評価実験

    有谷友汰, 斎藤隼, 梅田大貴, 狩野開, 道辻健太, WANG Tao, WANG Xudong, 石山敦士, 植田浩史, 福田光宏, 畑中吉治, 野口聡

    低温工学・超電導学会講演概要集   88th   145  2013.12

    J-GLOBAL

  • REBCOコイルの遮へい電流磁場の低減に関する検討

    植田浩史, 齋藤隼, 有谷友汰, 梅田大貴, 道辻健太, 狩野開, WANG Tao, WANG Xudong, 石山敦士, 福田光宏, 畑中吉治, 野口聡

    低温工学・超電導学会講演概要集   88th   15  2013.12

    J-GLOBAL

  • Feature: Development Trends of Superconducting Cables

    ISHIYAMA Atsushi

    TEION KOGAKU   48 ( 11 ) 538 - 538  2013.11

    DOI CiNii

  • Classification of EEG Steady-State Visual Evoked Potential Using Stationary Subspace Analysis

    SHIRATORI Tomoki, NAMBA Hironao, MATSUMOTO Takashi, ISHIYAMA Atsushi

    IEICE technical report. Neurocomputing   113 ( 315 ) 13 - 16  2013.11

     View Summary

    We attempted to use signal separation algorithm Stationary Subspace Analysis (SSA) for classification of EEG steady-state visual evoked potential (SSVEP). EEG signals were subjected to Fast Fourier Transform (FFT) to extract features. We used Support Vector Machine (SVM) for classification. We compared accuracy rates of the proposed method with a baseline method where no separation algorithm was used. Of the 12 subjects, 11 showed classification accuracy improvements with the proposed method against the baseline method. The average classification rate improved from 91.4% to 96.2%.

  • 3Experiment and Simulation of Screening Current and Magnetic Field Distribution in HTS Coil

    UEDA Hiroshi, FUKUDA Mitsuhiro, HATANAKA Kichiji, NOGUCHI So, SAITO Jun, ARIYA Yuta, MICHITSUJI Kenta, WANG Tao, WANG Xudong, ISHIYAMA Atsushi

    電気学会超電導応用電力機器研究会資料   2013 ( 22 ) 101 - 106  2013.09

    CiNii J-GLOBAL

  • Development of Next Generation HTS Cyclotron : Experiments on Winding Accuracy for YBCO Double Pancake Coil

    UMEDA Hirotaka, SAITO Jun, ARIYA Yuta, KARINO Hiraku, MICHITSUJI Kenta, WANG Tao, WANG Xudong, ISHIYAMA Atsushi, UEDA Hiroshi, WATANABE Tomonori, NAGAYA Shigeo

      2013 ( 22 ) 107 - 112  2013.09

  • Experiment and Numerical Simulation on Quench Detection in Cryocooler-cooled YBCO Coil for SMES Application

    ARAKAWA Issei, MINAMI Katsuhiko, NAKADA Erika, MASUI Yuta, WANG Xudong, ISHIYAMA Atsushi, WATANABE Tomonori, NAGAYA Shigeo, UEDA Hiroshi

      2013 ( 22 ) 87 - 92  2013.09

  • Numerical Structural Analysis on High Strength REBCO Pancake Coil

    WANG Xudong, ISHIYAMA Atsushi, TUJIMURA Takuya, YAMAKAWA Hiroshi, UEDA Hiroshi, WATANABE Tomonori, NAGAYA Shigeo

      2013 ( 22 ) 81 - 86  2013.09

  • Cooling Simulation of HTS Superconducting Cable Cooled by Subcooled LN2

    SATO Yusuke, AGATSUMA Koh, WANG Xudong, ISHIYAMA Atsushi

      2013 ( 22 ) 43 - 47  2013.09

  • Y系ダブルパンケーキコイルの遮へい電流磁場解析

    植田浩史, 福田光宏, 畑中吉治, 野口聡, 齋藤隼, 有谷友汰, 狩野開, 道辻健太, WANG Tao, WANG Xudong, 石山敦士, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集   87th   11  2013.05

    J-GLOBAL

  • Development of High-Strength Pancake-coil Structure : "Yoroi-coil"

    WATANABE Tomonori, NAGAYA Shigeo, HIRANO Naoki, AWAJI Satoshi, OGURO Hidetoshi, ISHIYAMA Atsushi, WANG Xudong

    TEION KOGAKU   48 ( 5 ) 213 - 219  2013.05

     View Summary

    A high-strength pancake-coil structure called "Yoroi-coil" (Y-based oxide superconductor and reinforcing outer integrated coil), in which superconducting wire and the reinforcing outer plates of the coil withstand electromagnetic force, was developed for high magnetic field applications. The double-pancake (DP) coil of this coil structure was prepared and verified for durability against electromagnetic forces using the hoop stress test. The coil achieved 1.5 kA transporting at 4.2 K in an 8 T backup magnetic field without degradation of transport properties. Maximum hoop stress at the hoop stress test reached 1.74 GPa, based on the calculations. This result confirmed that the "Yoroi-coil" structure has the capability to withstand large hoop stress, which exceeds the tensile strength of Y-based coated conductors, not only owing to the strength of superconducting wire but also owing to the integration of the whole coil structure itself. Additionally, the strengthening effect of the structure was verified by analysis.

    DOI CiNii

  • Design Optimization of Coils for Next Generation HTS Cyclotron

    UEDA Hiroshi, FUKUDA Mitsuhiro, HATANAKA Kichiji, WANG Xudong, ISHIYAMA Atsushi, NOGUCHI So, KASHIMA Naoji, NAGAYA Shigeo, MIYAHARA Nobuyuki

      2013 ( 1 ) 55 - 60  2013.01

    CiNii

  • Experiments on Detection of Normal Transition for Cryocooler-cooled YBCO Model Coil for the Application of SMES-Current Measurement of Bundle Conductor-

    大西秀明, 増井裕太, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 平野直樹, 長屋重夫

    電気学会超電導応用電力機器研究会資料   ASC-13 ( 1-21 )  2013

    J-GLOBAL

  • 高温超電導線材の耐放射線性評価:超電導特性

    有谷友汰, 齋藤隼, 道辻健太, 狩野開, WANG Xudong, 石山敦士, 植田浩史, 宮原信幸

    電気学会全国大会講演論文集   2013 ( 5 )  2013

    J-GLOBAL

  • SMES応用を想定した伝導冷却YBCOモデルコイルの常電導転移検出法(その1):実験

    中田恵理香, 増井裕太, 大西秀明, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 平野直樹, 長屋重夫

    電気学会全国大会講演論文集   2013 ( 5 )  2013

    J-GLOBAL

  • SMES応用を想定した伝導冷却YBCOモデルコイルの常電導転移検出実験法(その2):解析

    南克彦, 増井裕太, 大西秀明, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 平野直樹, 長屋重夫

    電気学会全国大会講演論文集   2013 ( 5 )  2013

    J-GLOBAL

  • YBCOパンケーキモデルコイルにおける巻線精度評価実験

    齋藤隼, 有谷友汰, 狩野開, 道辻健太, 矢崎真二郎, 柄澤彰良, 王旭東, 石山敦士, 宮原信幸, 植田浩史, 鹿島直二, 長屋重夫

    電気学会全国大会講演論文集   2013 ( 5 )  2013

    J-GLOBAL

  • 伝導冷却パラフィン含浸モデルコイル伝熱特性評価実験

    荒川一誠, 増井裕太, WANG Xudong, 石山敦士, 渡辺智則, 平野直樹, 長屋重夫, 植田浩史

    電気学会全国大会講演論文集   2013 ( 5 )  2013

    J-GLOBAL

  • SMES応用を想定したYBCOモデルコイルの常電導転移・転流解析

    南克彦, 荒川一誠, 中田恵理香, 増井裕太, WANG Xudong, 石山敦士, 渡部智則, 長屋重夫, 植田浩史

    低温工学・超電導学会講演概要集   87th  2013

    J-GLOBAL

  • SMES用Y系超電導コイルのクエンチ検出と保護

    中田恵理香, 荒川一誠, 南克彦, 増井裕太, WANG Xudong, 石山敦士, 渡部智則, 長屋重夫, 植田浩史

    低温工学・超電導学会講演概要集   87th  2013

    J-GLOBAL

  • Y系ダブルパンケーキコイルの遮へい電流磁場評価実験

    WANG Tao, 齋藤隼, 有谷友汰, 狩野開, 道辻健太, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集   87th  2013

    J-GLOBAL

  • SMES応用を想定したYBCOモデルコイルの常電導転移検出実験

    荒川一誠, 南克彦, 中田恵理香, 増井裕太, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集   87th  2013

    J-GLOBAL

  • 次世代超伝導サイクロトロンの開発:Y系ダブルパンケーキコイルの磁場精度評価

    有谷友汰, 斎藤隼, 狩野開, 道辻健太, WANG Tao, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集   87th  2013

    J-GLOBAL

  • 次世代超電導サイクロトロンの開発:非円形YBCOパンケーキコイルの試作

    梅田大貴, 有谷友汰, 斎藤隼, 狩野開, 道辻健太, WANG Tao, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集   88th  2013

    J-GLOBAL

  • SMES用YBCOコイルを想定した常電導転移検出法

    南克彦, 中田恵理香, 荒川一誠, 増井裕太, WANG Xudong, 石山敦士, 植田浩史, 渡部智則, 長屋重夫

    低温工学・超電導学会講演概要集   88th  2013

    J-GLOBAL

  • Development of high strength pancake-coil with novel strengthening structure

    NAGAYA Shigeo, WATANABE Tomonori, HIRANO Naoki, AWAJI Satoshi, OGURO Hidetoshi, ISHIYAMA Atsushi, WANG Xudong

      2013 ( 1 ) 97 - 102  2013.01

  • Development of Next Generation HTS Cyclotron : Neutron Experiments on HTSs

    MICHITSUJI Kenta, KARINO Hiraku, WANG Xudong, ISHIYAMA Atsushi, UEDA Hiroshi, MIYAHARA Nobuyuki

    電気学会超電導応用電力機器研究会資料   2013 ( 1 ) 67 - 72  2013.01

    J-GLOBAL

  • Development of Next Generation HTS Cyclotron : Experiments on Winding Accuracy for YBCO Pancake Coil

    WANG Tao, KARINO Hiraku, MICHITSUJI Kenta, YAZAKI Shinjiro, KARASAWA Akira, WANG Xudong, ISHIYAMA Atsushi, MIYAHARA Nobuyuki, UEDA Hiroshi, KASHIMA Naoji, NAGAYA Shigeo

      2013 ( 1 ) 61 - 66  2013.01

  • Feature : Japan Science and Technology Agency's Program "S-Innova : Creation of Advanced HTS Energy and Electronics Industry"

    ISHIYAMA Atsushi

      48 ( 1 )  2013.01

  • 次世代超電導サイクロトロンの開発:開発課題

    石山敦士, WANG Xudong, 植田浩史, 福田光宏, 畑中吉治, 野口聡, 長屋重夫, 鹿島直二, 宮原信幸

    低温工学・超電導学会講演概要集   86th   186  2012.11

    J-GLOBAL

  • 次世代超電導サイクロトロンの開発:遮へい電流の影響の検討

    植田浩史, 福田光宏, 畑中吉治, 野口聡, 石山敦士

    低温工学・超電導学会講演概要集   86th   125  2012.11

    J-GLOBAL

  • 次世代超電導サイクロトロンの開発:コイル形状の設計最適化

    植田浩史, 福田光宏, 畑中吉治, 野口聡, 石山敦士, 長屋重夫, 鹿島直二, 宮原信幸

    低温工学・超電導学会講演概要集   86th   124  2012.11

    J-GLOBAL

  • 3D Electromagnetic Simulation of Spatial and Temporal Behavior of Magnetic Field Distribution Caused by Shielding Current in HTS Coil for Accelerator Application

    UEDA Hiroshi, FUKUDA Mitsuhiro, HATANAKA Kichiji, NOGUCHI So, ISHIYAMA Atsushi

    電気学会超電導応用電力機器研究会資料   2012 ( 1 ) 47 - 51  2012.06

    CiNii J-GLOBAL

  • 心磁図マップの統計的パターン認識を用いたマウス虚血性心疾患検出法の開発

    相原 伸平, 石山 敦士, 葛西 直子, 小野 弓絵, 南沢 享

    日本生体磁気学会誌   25 ( 1 ) 178 - 179  2012.06

  • Characteristic change in HTSs due to temperature rise

    YAZAKI Shinjiro, KARASAWA Akira, KOTOYORI Takuya, KARINO Hiraku, MICHITSUJI Kenta, ARIYA Yuta, SAITO Jun, ISHIYAMA Atsushi, MIYAHARA Nobuyuki

      2012 ( 1 ) 83 - 86  2012.06

  • Local Degradation Characteristics of Coated Conductors due to Overcurrent

    WANG Xudong, ISHIYAMA Atsushi, YAGI Masashi, MARUYAMA Osamu, OHKUMA Takeshi

      2012 ( 1 ) 35 - 40  2012.06

  • Overcurrent Characteristics of 275-kV-class YBCO Power Cable with Hollow Former

    WANG Xudong, ISHIYAMA Atsushi, YAGI Masashi, MARUYAMA Osamu, OHKUMA Takeshi

      2012 ( 1 ) 23 - 28  2012.06

  • Development of Next Generation HTS cyclotron : high-accuracy winding technique for pancake coil

    ISHIYAMA A.

    Abstracts of CSJ Conference   86   123 - 123  2012

    CiNii

  • 加速器応用を想定した高温超電導コイルの遮へい電流と発生磁場分布の3次元解析

    植田浩史, 福田光宏, 畑中吉治, 石山敦士

    電気学会全国大会講演論文集   2012 ( 5 )  2012

    J-GLOBAL

  • SMES用Y系超電導コイルにおけるクエンチ検出方法の検討

    増井裕太, 室町和輝, 鈴木貴裕, 大西秀明, 石山敦士, 渡部智則, 平野直樹, 長屋重夫, 植田浩史

    電気学会全国大会講演論文集   2012 ( 5 )  2012

    J-GLOBAL

  • 次世代超電導サイクロトロンの開発:YBCOパンケーキコイルの磁場精度解析

    WANG Tao, 石山敦士, 植田浩史, 福田光宏, 畑中吉治, 長屋重夫, 鹿島直二, 宮原信幸

    低温工学・超電導学会講演概要集   86th  2012

    J-GLOBAL

  • 次世代超電導サイクロトロンの開発:YBCOパンケーキモデルコイルにおける巻線精度評価

    狩野開, 道辻健太, 矢崎真二郎, 柄澤彰良, WANG Xudong, 石山敦士, 宮原信幸, 植田浩史, 鹿島直二, 長屋重夫

    低温工学・超電導学会講演概要集   86th  2012

    J-GLOBAL

  • 次世代超電導サイクロトロンの開発:高温超電導線材の中性子照射特性(放射化評価)

    宮原信幸, 狩野開, 道辻健太, 矢崎真二郎, 柄澤彰良, WANG Xudong, 石山敦士, 植田浩史

    低温工学・超電導学会講演概要集   86th  2012

    J-GLOBAL

  • 次世代超電導サイクロトロンの開発:高温超電導線材の中性子照射特性(機械特性)

    道辻健太, 狩野開, 矢崎真二郎, 柄澤彰良, WANG Xudong, 石山敦士, 植田浩史, 宮原信幸

    低温工学・超電導学会講演概要集   86th  2012

    J-GLOBAL

  • SMES用伝導冷却YBCOコイルにおける常電導転移検出実験

    増井裕太, 大西秀明, 石山敦士, 渡部智則, 平野直樹, 長屋重夫, 植田浩史

    低温工学・超電導学会講演概要集   86th  2012

    J-GLOBAL

  • 次世代超電導サイクロトロンの開発:高温超電導線材の中性子照射特性(超電導特性)

    道辻健太, 狩野開, 矢崎真二郎, 柄澤彰良, WANG Xudong, 石山敦士, 植田浩史, 宮原信幸

    低温工学・超電導学会講演概要集   86th  2012

    J-GLOBAL

  • SMES用YBCOコイルを想定した伝導冷却下での銅モデルコイルの伝熱特性評価

    増井裕太, 琴寄拓哉, 石山敦士, 渡部智則, 平野直樹, 長屋重夫, 植田浩史

    低温工学・超電導学会講演概要集   86th  2012

    J-GLOBAL

  • Feasibility Study on a 400 kW-3600 rpm REBCO Fully Superconducting Motor

    Iwakuma, Masataka, Ogata, Toshiyuki, Tomoda, Shinichiro, Kisu, Takanobu, Yoshida, Yutaka, Ishiyama, Atsushi, Yamada, Yutaka, Izumi, Teruo, Shiohara, Yuh

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   22 ( 3 )  2012

    DOI

  • Quench detection and Protection of Conduction-cooled YBCO Coils for SMES application

    ISHIYAMA Atsushi, WANG Xudong, MUROMACHI Kazuki, SHIKIMACHI Koji, HIRANO Naoki, NAGAYA Shigeo, UEDA Hiroshi

      2011 ( 25 ) 45 - 50  2011.06

  • Current Margin and Aging degradation Characteristics of 275kV YBCO Superconducting Power Cable

    WANG Xudong, ISHIYAMA Atsushi, YAGI Masashi, MARUYAMA Osamu, OHKUMA Takeshi

      2011 ( 25 ) 39 - 44  2011.06

    CiNii

  • Over-current Experiments and Numerical Simulations on 66kV REBCO Superconducting Model Cable

    WANG Xudong, ISHIYAMA Atsushi, OHYA Masayoshi, MARUYAMA Osamu, OHKUMA Takeshi

      2011 ( 25 ) 33 - 38  2011.06

    CiNii

  • Application to Magnetic Levitation

    TSUDA Makoto, ISHIYAMA Atsushi

    TEION KOGAKU   46 ( 3 ) 94 - 101  2011.03

     View Summary

    Magnetic levitation systems using HTS bulks, such as magnetic bearing devices for flywheel energy storage systems, transporters, linear actuators, magnetic gears and so on, have been developed by many research groups. Most of the HTS magnetic levitation systems are composed of HTS bulks and permanent magnets. "Stable magnetic levitation without any other control system" is a specific characteristic of the HTS bulks. A non-contact spin processor and a magnetic-levitation seismic isolation device are introduced as magnetic levitation systems that are composed of HTS bulks and permanent magnets. Furthermore, an active magnetic levitation system using spherical HTS bulks for inertial nuclear fusion and a three-dimensional HTS actuator are introduced as magnetic levitation systems with HTS bulks and electromagnets. Levitation force, levitation gap and stability are closely related to the size and shape of the HTS bulk, the magnetic field distribution around the HTS bulk, the conditions in the field-cooling process of the HTS bulk and so on. Achieving large levitation force, large levitation gap and highly stable levitation is very important for practical use of the HTS magnetic levitation system. Theoretical analysis using a numerical simulation code for understanding electromagnetic behaviors within the HTS bulk is useful for improving the levitation force, levitation gap and stability. Finally, numerical techniques based on the finite element method are introduced in this paper.

  • Trial Design of Next Generation HTS Cyclotron

    ISHIYAMA A.

    Abstracts of CSJ Conference   84   135 - 135  2011

    CiNii

  • Development of Next Generation HTS Cyclotron

    ISHIYAMA A.

    Abstracts of CSJ Conference   84   134 - 134  2011

    CiNii

  • 次世代重粒子線がん治療用超電導加速器「先進ハイブリッドサイクロトロン」の開発

    石山敦士, WANG Xudong, 福田光宏, 植田浩史, 畑中吉治, 長屋重夫, 鹿島直二, 宮原信幸, 横田渉

    電気学会全国大会講演論文集   2011 ( 5 )  2011

    J-GLOBAL

  • 次世代重粒子線がん治療用超電導加速器「先進ハイブリッドサイクロトロン」の試設計

    石山敦士, WANG Xudong, 福田光宏, 植田浩史, 畑中吉治, 長屋重夫, 鹿島直二, 宮原信幸, 横田渉

    電気学会全国大会講演論文集   2011 ( 5 )  2011

    J-GLOBAL

  • 次世代高温超電導サイクロトロンのための高温超電導コイルの遮へい電流による磁場の空間的・時間的変化-(1)3次元電磁場解析モデルおよび定式化-

    植田浩史, 福田光宏, 畑中吉治, 石山敦士

    低温工学・超電導学会講演概要集   85th  2011

    J-GLOBAL

  • 中性子照射による高温超電導体への影響

    琴寄拓哉, 神林佑, 柄澤彰良, 矢崎真二郎, 石山敦士, 宮原信幸, 植田浩史

    低温工学・超電導学会講演概要集   85th  2011

    J-GLOBAL

  • Y系高温超電導モータの開発

    山田穣, 植田浩史, 和泉輝郎, 齊藤隆, 塩原融, 岩熊成卓, 石山敦士

    低温工学・超電導学会講演概要集   85th  2011

    J-GLOBAL

  • 次世代高温超電導サイクロトロンの試設計

    石山敦士, WANG Xudong, 植田浩史, 福田光宏, 畑中吉治, 長屋重夫, 鹿島直二, 宮原信幸, 横田渉

    低温工学・超電導学会講演概要集   84th  2011

    J-GLOBAL

  • SMES用YBCO超電導コイルのクエンチ検出と保護に関する数値解析評価

    石山敦士, 大西秀明, WANG Xudong, 植田浩史, 渡部智則, 平野直樹, 長屋重夫

    低温工学・超電導学会講演概要集   85th  2011

    J-GLOBAL

  • 次世代高温超電導サイクロトロンのための高温超電導コイルの遮へい電流による磁場の空間的・時間的変化-(2)計算例-

    植田浩史, 福田光宏, 畑中吉治, 石山敦士

    低温工学・超電導学会講演概要集   85th  2011

    J-GLOBAL

  • 医薬用たんぱく質の高速分離・精製・回収用高勾配磁気分離システムのフィルターの検討

    植田浩史, 我妻洸, 古瀬充穂, 淵野修一郎, 柁川一弘, 石山敦士, 小泉達雄

    低温工学・超電導学会講演概要集   84th  2011

    J-GLOBAL

  • 特集「超電導発見から100 年」に寄せて

    石山 敦士, 島崎 毅

    低温工学   46 ( 12 ) S2 - S2  2011

  • Feature : Materials & Power Applications of Coated Conductors (M-PACC) Project (Japanese National Project)

    ISHIYAMA Atsushi

    TEION KOGAKU   46 ( 6 ) 319 - 319  2011

  • Current Margin against a Fault Current in REBCO Coated Conductors for 66 KV Class HTS Power Cable

    MOMOTARI Hiroshi, ARAI Michio, KOJIMA Kentaro, WANG Xudong, ISHIYAMA Atsushi, OHYA Masayoshi, OHMATSU Kazuya, OHKUMA Takeshi, MARUYAMA Osamu

      2011 ( 15 ) 25 - 30  2011.01

    CiNii

  • Feasibility study on "Advanced Hybrid Cyclotron" utilizing High-Temperature Superconducting Technology

    ISHIYAMA Atsushi, WANG Xudong, FUKUDA Mitsuhiro, HATANAKA Kichiji, UEDA Hiroshi, NAGAYA Shigeo, KASHIMA Naoji, MIYAHARA Nobuyuki

    電気学会超電導応用電力機器研究会資料   2011 ( 1 ) 47 - 52  2011.01

    J-GLOBAL

  • Effect of Neutron Irradiation on High-Temperature Superconductors

    KAMBAYASHI Yu, AOKI Toru, ISHIYAMA Atsashi, MIYAHARA Nobuyuki, UEDA Hiroshi, KASHIMA Naoji, NAGAYA Shigeo

    電気学会超電導応用電力機器研究会資料   2011 ( 1 ) 41 - 45  2011.01

    J-GLOBAL

  • Development of 66kV/5 kA-class "3-in-One" HTS cable using REBCO wires

    OHYA Masayoshi, YUMURA Hiroyasu, HIROTA Hirofumi, MASUDA Takato, OHMATSU Kazuya, AMEMIYA Naoyuki, ISHIYAMA Atsushi, MARUYAMA Osamu, OHKUMA Takeshi

      2011 ( 1 ) 11 - 16  2011.01

    CiNii

  • 異分野融合によるイノベーションの創出

    石山 敦士

    低温工学   45 ( 6 )  2010.06

  • Quench Behavior and Protection in Conduction-cooled YBCO Coils for SMES

    ISHIYAMA Atsushi, UEDA Hiroshi, SHIKIMACHI Koji, HIRANO Naoki, NAGAYA Shigeo

    電気学会超電導応用電力機器研究会資料   2010 ( 17 ) 101 - 106  2010.06

    J-GLOBAL

  • Development of Next-generation Superconducting Cyclotron

    ISHIYAMA Atsushi, UEDA Hiroshi, FUKUDA Mitsuhiro, HATANAKA Yoshiji, MIYAHARA Nobuyuki, YOKOTA Wataru, KASHIMA Naoji, NAGAYA Shigeo

    電気学会超電導応用電力機器研究会資料   2010 ( 17 ) 83 - 88  2010.06

    J-GLOBAL

  • AC Over-Current Characteristics of REBCO Coated Conductors

    WANG Xudong, MOMOTARI Hiroshi, ISHIYAMA Atsushi, OHYA Masayoshi, OHMATSU Kazuya, FUJIWARA Noboru

      2010 ( 17 ) 57 - 62  2010.06

  • Over-current characteristics in 66kV REBCO Superconducting Model Cable

    WANG Xudong, ISHIYAMA Atsushi, OHYA Masayoshi, FUJIWARA Noboru

      2010 ( 17 ) 51 - 55  2010.06

  • Recent progress of developing YBCO HTS power cables

    FUJIWARA Noboru, ICHIKAWA Hiroshi, AMEMIYA Naoyuki, ISHIYAMA Atsushi, HAYAKAWA Naoki, MUKOYAMA Shinichi, YAGI Masashi, MASUDA Takato, OHYA Masayoshi, OHMATSU Kazuya, SAITOH Takashi, AOKI Yuji

      2010 ( 17 ) 45 - 50  2010.06

  • YBCO超電導線材の過電流パルス通電による特性劣化試験

    WANG XUDONG, ARAI MICHIO, ISHIYAMA ATSUSHI, SAITO TAKASHI, AOKI YUJI, YAGI MASASHI, SAKAI NAOMICHI, FUJIWARA NOBORU

    低温工学・超電導学会講演概要集   82nd   73  2010.05

    J-GLOBAL

  • Development of 275kV class HTS power cable

    MUKOYAMA Shinichi, YAGI Masashi, YONEMURA Tokui, NOMURA Tomoyuki, FUJIWARA Noboru, ICHIKAWA Yuuji, AOKI Yuuji, SAITOH Takashi, AMEMIYA Naoyuki, ISHIYAMA Atsushi

      2010 ( 1 ) 29 - 33  2010.01

    CiNii

  • Stability and Protection of Cryocooler-cooled YBCO Coils for SMES with Toroidal Arrangement

    植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    電気学会超電導応用電力機器研究会資料   ASC-10 ( 1.3-9.11-16 )  2010

    J-GLOBAL

  • Neutron Iradiation Experiment of HTS for Prticle Radiation Therapy of Cancer

    陸旭棟, 青木徹, 神林佑, 植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 宮原信幸

    電気学会超電導応用電力機器研究会資料   ASC-10 ( 1.3-9.11-16 )  2010

    J-GLOBAL

  • 球状バルク超電導体のアクティブ磁気浮上における安定性評価

    WANG Tao, 陸旭棟, 青木徹, 阿部昂機, 植田浩史, 我妻洸, 石山敦士, 岩本晃史, 柳長門, 三戸利行

    電気学会全国大会講演論文集   2010 ( 5 )  2010

    J-GLOBAL

  • 275kV系統YBCO超電導ケーブルの定常運転時の伝熱特性

    神谷侑司, 百足弘史, 佐藤俊祐, WANG Xudong, 植田浩史, 石山敦士, 八木正史, 藤原昇

    電気学会全国大会講演論文集   2010 ( 5 )  2010

    J-GLOBAL

  • YBCO超電導線材の交流過電流通電特性

    児島健太郎, 新井道生, 河野秀太郎, WANG Xudong, 植田浩史, 石山敦士, 大屋正義, 湯村洋康, 藤原昇

    電気学会全国大会講演論文集   2010 ( 5 )  2010

    J-GLOBAL

  • AC Loss Evaluation of SMES Coils with Y-based Coated Conductor

    柁川一弘, 船木和夫, 植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    超伝導システム科学研究センター報告   7  2010

    J-GLOBAL

  • 高温超電導線材の中性子照射実験

    青木徹, 陸旭棟, 神林佑, 植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 宮原信幸

    電気学会全国大会講演論文集   2010 ( 5 )  2010

    J-GLOBAL

  • SMES用冷凍機伝導冷却Y系超電導コイルを想定した銅ダミーコイルの熱特性評価解析

    室町和輝, 青木佳明, 川井優季, 植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    電気学会全国大会講演論文集   2010 ( 5 )  2010

    J-GLOBAL

  • 銅メッキYBCO超電導線材の疲労特性試験

    鈴木貴裕, 川井優季, 青木佳明, 植田浩史, 石山敦士, 鹿島直二, 渡辺智則, 平野直樹, 山本潔

    電気学会全国大会講演論文集   2010 ( 5 )  2010

    J-GLOBAL

  • 超伝導線材ならびにコイル構成材料の耐放射線性に関する研究

    石山敦士, 植田浩史, 陸旭東, 青木徹, 神林佑, 宮原信幸

    NIRS-M (National Inst. of Radiological Sciences)   ( 233 )  2010

    J-GLOBAL

  • 高温超電導線材の中性子照射実験

    神林佑, 青木徹, 植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 宮原信幸

    低温工学・超電導学会講演概要集   82nd  2010

    J-GLOBAL

  • SMES用伝導冷却Y系超電導モデルコイルの通電・伝熱特性評価

    鈴木貴裕, 室町和輝, 青木佳明, 植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    低温工学・超電導学会講演概要集   82nd  2010

    J-GLOBAL

  • REBCO超電導線材の過電流パルス通電による特性劣化要因について

    金光雅也, 新井道生, WANG Xudong, 植田浩史, 石山敦士, 斉藤隆, 大松一也, 大屋正義, 和泉輝郎, 藤原昇

    低温工学・超電導学会講演概要集   82nd  2010

    J-GLOBAL

  • SMES用伝導冷却高温超電導コイルのクエンチ保護

    室町和輝, 鈴木貴裕, 青木佳明, 植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    低温工学・超電導学会講演概要集   82nd  2010

    J-GLOBAL

  • Appropriate auditory stimuli for P300 brain-computer interface

    Nojo, Hideki, Kawasaki, Minoru, Jyo, Tetsu, Ishiyama, Atsushi, Kasai, Naoko, Ono, Yumie

    NEUROSCIENCE RESEARCH   68   E327 - E327  2010

    DOI

  • Measurements and Analyses on Abnormal Magnetocardiography of Heart-disease-model Mice Using SQUID System for Small Animals

    ISHIYAMA Atsushi, TATENO Yusuke, MINAMISAWA Susumu, KASAI Naoko, ONO Yumie

      81   190 - 190  2009.11

    CiNii

  • The plan and progress report of developing YBCO HTS power cables

    FUJIWARA Noboru, ICHIKAWA Hiroshi, AMEMIYA Naoyuki, ISHIYAMA Atsushi, MUKOYAMA Shinichi, MASUDA Takato, SAITOH Takashi, AOKI Yuji

      2009 ( 20 ) 49 - 52  2009.06

    CiNii

  • Stability and Protection of Coils Wound with YBCO Bundle Conductor

    UEDA Hiroshi, ISHIYAMA Atsushi, SJIKIMACHI Koji, HIRANO Naoki, NAGAYA Shigeo

      2009 ( 20 ) 85 - 89  2009.06

    CiNii

  • スラッシュ窒素冷却下における高温超電導線材の過電流通電特性(数値解析)

    百足弘史, 瓜生季邦, 佐藤俊祐, WANG Xudong, 植田浩史, 石山敦士, 淵野修一郎, 古瀬充穂, 池内正充, 大野隆介

    電気学会全国大会講演論文集   2009 ( 5 )  2009

    J-GLOBAL

  • YBCO超電導線材の過電流パルス通電試験前後における層間接触評価

    梶谷秀樹, 新井道生, 河野秀太郎, 西尾幸恭, 植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 八木正史, 向山晋一, 加藤英幸, 塩原融

    電気学会全国大会講演論文集   2009 ( 5 )  2009

    J-GLOBAL

  • YBCO超電導線材の疲労特性

    青木佳明, 田中洋輔, 川井優季, 植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 塩原融

    電気学会全国大会講演論文集   2009 ( 5 )  2009

    J-GLOBAL

  • スラッシュ窒素冷却下における高温超電導線材の過電流通電特性(実験)

    瓜生季邦, 百足弘史, 佐藤俊祐, WANG Xudong, 植田浩史, 石山敦士, 淵野修一郎, 古瀬充穂, 池内正充, 大野隆介

    電気学会全国大会講演論文集   2009 ( 5 )  2009

    J-GLOBAL

  • YBCO超電導ケーブルの過電流通電特性

    WANG Xudong, 植田浩史, 石山敦士, 八木正史, 向山晋一, 鹿島直二, 長屋重夫, 塩原融

    電気学会全国大会講演論文集   2009 ( 5 )  2009

    J-GLOBAL

  • Thermal Characteristics of 275kV Class YBCO Superconducting Power Cable-Effect of Dielectric Loss-

    WANG Xudong, 植田浩史, 石山敦士, 八木正史, 藤原昇

    電気学会超電導応用電力機器研究会資料   ASC-09 ( 20-39 )  2009

    J-GLOBAL

  • AC Loss Evaluation of Pancake Coils for Y-based SMES with Toroidal Arrangement

    柁川一弘, 船木和夫, 植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    電気学会超電導応用電力機器研究会資料   ASC-09 ( 20-39 )  2009

    J-GLOBAL

  • スラッシュ窒素の電気絶縁特性

    淵野修一郎, 古瀬充穂, 名取尚武, 池内正充, 大野隆介, 石山敦士, 植田浩史

    電気学会全国大会講演論文集   2009 ( 5 )  2009

    J-GLOBAL

  • スラッシュ窒素冷却下における高温超電導線材の過電流通電特性

    百足弘史, 瓜生季邦, 佐藤俊祐, WANG Xudong, 植田浩史, 石山敦士, 淵野修一郎, 古瀬充穂, 池内正充, 大野隆介

    低温工学・超電導学会講演概要集   80th  2009

    J-GLOBAL

  • コイル巻線化されたYBCO集合化導体の常電導伝播特性解析

    植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    低温工学・超電導学会講演概要集   80th  2009

    J-GLOBAL

  • 66kV系統YBCO超電導ケーブルの過電流通電特性解析

    WANG Xudong, 植田浩史, 石山敦士, 大屋正義, 湯村洋康, 藤原昇, 塩原融

    低温工学・超電導学会講演概要集   80th  2009

    J-GLOBAL

  • 数値シミュレーションによるTFコイル用CIC導体内の電流分布解析

    梶谷秀樹, 植田浩史, 石山敦士, 村上陽之, 小泉徳潔, 奥野清

    低温工学・超電導学会講演概要集   81st  2009

    J-GLOBAL

  • 275kV系統YBCO超電導ケーブルの定常運転時の伝熱特性

    瓜生季邦, 百足弘史, 佐藤俊祐, WANG Xudong, 植田浩史, 石山敦士, 八木正史, 齊藤隆, 青木裕治, 藤原昇, 塩原融

    低温工学・超電導学会講演概要集   80th  2009

    J-GLOBAL

  • 球状バルク超電導体の浮上安定性評価

    植田浩史, 陸旭棟, 青木徹, 石山敦士, 岩本晃史, 柳長門, 三戸利行

    低温工学・超電導学会講演概要集   80th  2009

    J-GLOBAL

  • 医薬用たんぱく質の高速分離・精製・回収用アフィニティー磁性ナノビーズ

    我妻洸, 淵野修一郎, 井村知弘, 古瀬充穂, 植田浩史, 石山敦士, 柁川一弘, 三宅新一, 五十嵐弘

    低温工学・超電導学会講演概要集   80th  2009

    J-GLOBAL

  • 球状バルク超電導体のアクティブ磁気浮上における安定性評価

    WANG Tao, 陸旭棟, 青木徹, 阿部昂機, 植田浩史, 我妻洸, 石山敦士, 岩本晃史, 柳長門, 三戸利行

    低温工学・超電導学会講演概要集   81st  2009

    J-GLOBAL

  • 高温超電導線材の中性子照射実験

    青木徹, 陸旭棟, 植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 宮原信幸

    低温工学・超電導学会講演概要集   81st  2009

    J-GLOBAL

  • YBCO超電導コイルの安定性と保護

    植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    低温工学・超電導学会講演概要集   81st  2009

    J-GLOBAL

  • 275kV系統YBCO超電導ケーブルの過電流通電特性解析

    WANG Xudong, 植田浩史, 石山敦士, 八木正史, 藤原昇

    低温工学・超電導学会講演概要集   81st  2009

    J-GLOBAL

  • 銅メッキYBCO超電導線材の疲労特性試験

    青木佳明, 川井優季, 植田浩史, 石山敦士, 鹿島直二, 渡辺智則, 平野直樹, 山本潔

    低温工学・超電導学会講演概要集   81st  2009

    J-GLOBAL

  • 66kV系統高温超電導ケーブルの過電流通電特性評価

    瓜生季邦, 百足弘史, 佐藤俊祐, WANG Xudong, 植田浩史, 石山敦士, 大屋正義, 増田孝人, 藤原昇

    低温工学・超電導学会講演概要集   81st  2009

    J-GLOBAL

  • 断面構造の異なるNb3Sn素線のCIC導体内における超電導特性の評価

    梶谷秀樹, 植田浩史, 石山敦士, 村上陽之, 小泉徳潔, 奥野清

    低温工学・超電導学会講演概要集   80th  2009

    J-GLOBAL

  • 高温超電導線材の疲労特性評価試験装置

    青木佳明, 川井優季, 植田浩史, 石山敦士, 式町浩二, 平野直樹, 長屋重夫

    低温工学・超電導学会講演概要集   80th  2009

    J-GLOBAL

  • YBCO超電導線材の交流過電流通電特性

    百足弘史, 新井道生, 河野秀太郎, WANG Xudong, 植田浩史, 石山敦士, 斎藤隆, 青木裕治, 八木正史, 藤原昇

    低温工学・超電導学会講演概要集   81st  2009

    J-GLOBAL

  • 医薬用たんぱく質の高速分離・精製・回収用高勾配磁気分離システムの回収率改善の検討

    植田浩史, 石山敦士, 我妻洸, 古瀬充穂, 淵野修一郎, 柁川一弘, 小泉達雄

    低温工学・超電導学会講演概要集   81st  2009

    J-GLOBAL

  • 医薬用たんぱく質の高速分離・精製・回収用高勾配磁気分離システムの回収率改善の検討

    植田浩史, 石山敦士, 我妻洸, 古瀬充穂, 淵野修一郎, 柁川一弘, 小泉達雄

    低温工学・超電導学会講演概要集   80th  2009

    J-GLOBAL

  • Measurements of Abnormal Magnetocardiography of Heart-Disease-Model Mice Using SQUID Measurement System for Small Animals

    ISHIYAMA Atsushi, TATENO Yusuke, MINAMISAWA Susumu, KASAI Naoko

      79   43 - 43  2008.11

    CiNii

  • Development of an YBCO HTS cable and cable joint

    YAGI Masashi, MUKOYAMA Shinichi, AMEMIYA Naoyuki, ISHIYAMA Atsushi, NAGAYA Shigeo, KASHIMA Naoji, SHIOHARA Yuh

      79   96 - 96  2008.11

    CiNii

  • MEG Measurement on Rats and Mice Using SQUID Measurement System for Small Animals

    ISHIYAMA Atsushi, IIJIMA Yoshikazu, KASAI Naoko, ONO Yumie

      79   107 - 107  2008.11

    CiNii

  • Degradation of YBCO coated conductors due to over-current pulse

    ISHIYAMA Atsushi, NISHIO Yukiyasu, KONO Hidetaro, WANG Xudong, UEDA Hiroshi, KASHIMA Naoji, MORI Masami, WATANABE Tomonori, NAGAYA Shigeo, IIJIMA Yasuhiro, SAITOH Takashi, YAGI Masashi, MUKOYAMA Shinichi, MATI Takato, SHIOHARA Yuh

      2008 ( 19 ) 47 - 51  2008.06

    CiNii

  • C-8-3 Improvement in Noise Tolerance of Signal Source Estimation for MEG by Tikhonov Regularization

    Okada Mayuko, Saitoh Yu, Ishiyama Atsushi, Watanabe Yutaka, Kasai Naoko

    Proceedings of the IEICE General Conference   2008 ( 2 ) 50 - 50  2008.03

    CiNii

  • C-8-1 MEG Measurement of Rats Using SQUID Measurement System for Small Animals

    Iijima Yoshikazu, Kasai Yusuke, Tateno Yusuke, Ishiyama Atsushi, Ono Yumie, Kasai Naoko

    Proceedings of the IEICE General Conference   2008 ( 2 ) 48 - 48  2008.03

    CiNii

  • Numerical Simulation of Critical Current Performance in Nb3Sn Strand Subjected to Periodic Bending Deformation

    村上陽之, 植田浩史, 石山敦士, 小泉徳潔, 奥野清

    電気学会論文誌 B   128 ( 6 )  2008

    J-GLOBAL

  • Overcurrent Characteristics of 10-m YBCO Superconducting Cable-Experiments and Simulations-

    WANG Xudong, 植田浩史, 石山敦士, 八木正史, 向山晋一, 鹿島直二, 長屋重夫, 塩原融

    電気学会超電導応用電力機器研究会資料   ASC-08 ( 19-26.28-31 )  2008

    J-GLOBAL

  • YBCO超電導ケーブル導体の過電流特性解析

    佐藤俊祐, WANG Xudong, 西尾幸恭, 植田浩史, 石山敦士, 八木正史, 向山晋一, 鹿島直二, 長屋重夫, 塩原融

    電気学会全国大会講演論文集   2008 ( 5 )  2008

    J-GLOBAL

  • Levitation Stability of Active Magnetic Levitation using Sphere-shaped HTS bulk

    石垣善弘, 陸旭棟, 植田浩史, 我妻洸, 石山敦士

    電気学会超電導応用電力機器研究会資料   ASC-08 ( 19-26.28-31 )  2008

    J-GLOBAL

  • コイル保護に基づくYBCO線材の安定化層厚の決定-SMES用コイルを想定して-

    川井優季, 植田浩史, 石山敦士

    電気学会全国大会講演論文集   2008 ( 5 )  2008

    J-GLOBAL

  • Radioactive analyses of HTS conductors

    植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 宮原信幸

    電気学会超電導応用電力機器研究会資料   ASC-08 ( 19-26.28-31 )  2008

    J-GLOBAL

  • 球状バルク超電導体のアクティブ磁気浮上の安定・位置制御

    陸旭棟, 菅兼治, 植田浩史, 我妻洸, 石山敦士

    電気学会全国大会講演論文集   2008 ( 5 )  2008

    J-GLOBAL

  • Strain and Fatigue Properties of YBCO coated conductors

    石山敦士, 田中洋輔, 川井優季, 佐藤俊祐, 植田浩史, 塩原融, 山田穣, 飯島康裕, 斉藤隆, 鹿島直二, 長屋重夫

    電気学会超電導応用電力機器研究会資料   ASC-08 ( 19-26.28-31 )  2008

    J-GLOBAL

  • 10m級YBCO超電導ケーブルの過電流通電特性

    WANG Xudong, 植田浩史, 石山敦士, 八木正史, 向山晋一, 鹿島直二, 長屋重夫, 塩原融

    低温工学・超電導学会講演概要集   78th  2008

    J-GLOBAL

  • 高温超電導線材の放射化実験

    植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 宮原信幸

    低温工学・超電導学会講演概要集   78th  2008

    J-GLOBAL

  • 球状バルク超電導体のアクティブ磁気浮上における安定性評価

    陸旭棟, 青木徹, 石垣善弘, 植田浩史, 我妻洸, 石山敦士, 岩本晃史, 柳長門, 三戸利行

    低温工学・超電導学会講演概要集   78th  2008

    J-GLOBAL

  • YBCO超電導線材の過電流パルス通電による特性劣化と層間剥離

    河野秀太郎, WANG Xudong, 西尾幸恭, 植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 八木正史, 向山晋一, 加藤英幸, 塩原融

    低温工学・超電導学会講演概要集   78th  2008

    J-GLOBAL

  • YBCO超電導線材の疲労特性

    川井優季, 田中洋輔, 植田浩史, 石山敦士, 飯島康裕, 斉藤隆, 鹿島直二, 長屋重夫, 山田穣, 塩原融

    低温工学・超電導学会講演概要集   79th  2008

    J-GLOBAL

  • YBCO超電導線材の疲労特性

    川井優季, 田中洋輔, 植田浩史, 石山敦士, 飯島康裕, 斉藤隆, 鹿島直二, 長屋重夫, 山田穣, 塩原融

    低温工学・超電導学会講演概要集   78th  2008

    J-GLOBAL

  • 高温超電導線材の放射化特性

    植田浩史, 石山敦士, 鹿島直二, 長屋重夫, 宮原信幸

    低温工学・超電導学会講演概要集   79th  2008

    J-GLOBAL

  • 球状バルク超電導体のアクティブ磁気浮上における安定性評価

    陸旭棟, 青木徹, 石垣善弘, 植田浩史, 我妻洸, 石山敦士, 岩本晃史, 柳長門, 三戸利行

    低温工学・超電導学会講演概要集   79th  2008

    J-GLOBAL

  • 医薬用たんぱく質の高勾配磁気分離システムによる高速分離・精製・回収用フィルターの設計

    植田浩史, 石山敦士, 我妻洸, 淵野修一郎, 古瀬充穂, 柁川一弘

    低温工学・超電導学会講演概要集   79th  2008

    J-GLOBAL

  • 医薬用たんぱく質の高速分離・精製・回収用高勾配磁気分離システム

    我妻洸, 淵野修一郎, 古瀬充穂, 柁川一弘, 植田浩史, 石山敦士

    低温工学・超電導学会講演概要集   79th  2008

    J-GLOBAL

  • Degradation of YBCO Coated Conductors Caused by Over-current Pulses

    X. Wang, H. Ueda, A. Ishiyama, Y. Iijima, T. Saitoh, N. Kashima, M. Mori, T. Watanabe, S. Nagaya, T. Katoh, T. Machi, Y. Shiohara

    Journal of Physics: Conference Series   97 ( 1 ) 12150  2008

     View Summary

    YBCO tapes are expected to be used in future high temperature superconductor (HTS) applications because they have excellent Jc characteristics at high temperatures and in high magnetic fields. For application to electric power devices such as transmission cables, transformers, and fault current limiters, the YBCO tapes might be subjected to a short-circuit fault current that is 10-30 times the normal operating current. In a worst-case scenario, YBCO tapes may degrade and burn. Therefore, it is important to clarify the mechanism of the degradation caused by an over-current pulse. This paper describes the experimental results of the degradation of the YBCO tapes through a series of over-current pulse tests. We focussed on the degradation temperature and carried out the experiments with different bending strains. Measurements were performed as a function of the amplitude of an over-current pulse for an operating temperature of 80 K (Gifford-McMahon cryocooler was adopted) in a self-field. We also examined a tape after the experiments with magneto-optical (MO) imaging, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron diffraction patterns. © 2008 IOP Publishing Ltd.

    DOI

  • Overcurrent Characteristics of 1 m Long Superconducting Model Cable using YBCO Coated Conductors

    H. Ueda, X. Wang, A. Ishiyama, S. Mukoyama, M. Yagi, N. Kashima, S. Nagaya, Y. Shiohara

    Journal of Physics: Conference Series   97   12168  2008

    DOI

  • Temporal Observation of Disease-Model Mice by MCG

    SHIMADA Ikuyo, KASAI Yusuke, KAKO Masahiro, OIKAWA Takatoshi, SAITOH Yu, ISHIYAMA Atsushi, ONO Yumie, KASAI Naoko, CHINONE Kazuo

      2007 ( 76 ) 29 - 32  2007.09

    CiNii

  • Effects of mastication on brain activity : Magnetoencephalographic study during human working memory

    DOWAKI Kanako, ISHIYAMA Atsushi, ONO Yumie, ONOZUKA Minoru, KASAI Naoko

      2007 ( 76 ) 33 - 38  2007.09

    CiNii

  • 心磁図を用いた妊婦と胎児の心拍変動の関連評価

    石山敦士, 神山拡己, 嶋田育代, 及川敬敏, 葛西祐介, 斎藤優, 中居賢司, 福島明宗, 伊藤学, 葛西直子

    日本生体磁気学会誌 特別号 第22回日本生体磁気学会大会論文集   20 ( 1 ) 122 - 123  2007.06

  • MCGによる心疾患モデルマウスの経時的観察

    葛西祐介, 加古真祥, 及川敬敏, 斎藤優, 小野弓絵, 石山敦士, 葛西直子, 茅根一夫

    日本生体磁気学会誌 特別号 第22回日本生体磁気学会大会論文集   20 ( 1 ) 212 - 213  2007.06

  • ガムチューイングが短期記憶獲得時のθ波活動に及ぼす影響

    堂脇可菜子, 小野弓絵, 石山敦士, 小野塚実

    日本生体磁気学会誌 特別号 第22回日本生体磁気学会大会論文集   20 ( 1 ) 258 - 259  2007.06

  • 脳内信号源推定における遺伝的アルゴリズムパラメータの最適化

    佐々木貴志, 嶋田裕介, 安斉和久, 及川敬敏, 葛西祐介, 斎藤優, 石山敦士, 渡邊裕, 葛西直子

    日本生体磁気学会誌 特別号 第22回日本生体磁気学会大会論文集   20 ( 1 ) 274 - 275  2007.06

  • チホノフの正則化を用いたMEG信号源推定

    斎藤優, 及川敬敏, 葛西祐介, 石山敦士, 渡邊裕, 葛西直子

    日本生体磁気学会誌 特別号 第22回日本生体磁気学会大会論文集   20 ( 1 ) 278 - 279  2007.06

  • Beamformerによる時間相関を持つ複数信号源推定

    及川敬敏, 木村壮志, 斎藤優, 葛西祐介, 石山敦士, 渡邊裕, 葛西直子

    日本生体磁気学会誌 特別号 第22回日本生体磁気学会大会論文集   20 ( 1 ) 282 - 283  2007.06

  • Thermal Characteristics of Small Cryocooler-cooled YBCO Coil

    ISHIYAMA Atsushi, ANDO Taketoshi, BAMBA Sadanori, UEDA Hiroshi, FUJI Hiroshi, IIJIMA Yasuhiro, SAITOH Takashi, SHIOHARA Yuh

      2007 ( 18 ) 49 - 54  2007.01

    CiNii

  • Transient Stability Characteristics of Parallel-Connected YBCO Coated Conductors Supposing Power Transmission Cables

    ISHIYAMA Atsushi, IWATA Takuya, WANG Xudong, UEDA Hiroshi, MUKOYAMA Shinichi, SHIOHARA Yuh

      2007 ( 18 ) 59 - 64  2007.01

    CiNii

  • YBCO超電導線材の過電流パルス通電による特性劣化-曲げひずみの影響-

    石山敦士

    平成19年度電気学会全国大会講演論文集    2007

    CiNii

  • Over-Current Characteristics of 1m-long Superconducting Model Cable using YBCO Coated Conductors-Experiment and Simulation-

    植田浩史, 西尾幸恭, WANG Xudong, 石山敦士, 八木正史, 向山晋一, 鹿島直二, 長屋重夫, 塩原融

    電気学会超電導応用電力機器研究会資料   ASC-07 ( 45-51 )  2007

    J-GLOBAL

  • 単層1m級YBCO超電導ケーブルの過電流通電特性評価(1.実験)

    石山敦士, 西尾幸恭, WANG Xudong, 岩田拓也, 植田浩史, 八木正史, 向山晋一, 塩原融

    低温工学・超電導学会講演概要集   76th  2007

    J-GLOBAL

  • YBCO超電導ケーブル導体の過電流特性解析

    石山敦士, WANG Xudong, 西尾幸恭, 植田浩史, 八木正史, 向山晋一, 鹿島直二, 長屋重夫, 塩原融

    低温工学・超電導学会講演概要集   77th  2007

    J-GLOBAL

  • CIC導体内におけるNb3Sn素線の超電導特性の数値解析・評価

    村上陽之, 植田浩史, 石山敦士, 小泉徳潔, 奥野清

    低温工学・超電導学会講演概要集   77th  2007

    J-GLOBAL

  • 単層1m級YBCO超電導ケーブル導体の過電流通電特性(2.解析)

    植田浩史, 西尾幸恭, 岩田拓也, WANG Xudong, 石山敦士, 八木正史, 向山晋一, 塩原融

    低温工学・超電導学会講演概要集   76th  2007

    J-GLOBAL

  • コイル保護に基づくYBCO線材の安定化層厚の決定-SMES用コイルを想定して

    番場貞徳, 植田浩史, 石山敦士

    低温工学・超電導学会講演概要集   77th  2007

    J-GLOBAL

  • 球状バルク超電導体のアクティブ磁気浮上における安定・位置制御

    菅兼治, 陸旭棟, 植田浩史, 我妻洸, 石山敦士

    低温工学・超電導学会講演概要集   77th  2007

    J-GLOBAL

  • Ic分布を考慮したYBCO超電導線材の常電導転移・伝播特性

    WANG Xudong, 土屋元計, 植田浩史, 石山敦士, 塩原融

    低温工学・超電導学会講演概要集   76th  2007

    J-GLOBAL

  • 3D Analysis of Electromagnetic Field in Bulk Superconductor

    H. Ueda, A. Ishiyama

    International Workshop on Processing and Applications of Superconducting (RE)BCO Large Grain Materials    2007

  • LHD超電導導体の過渡安定性解析

    野口聡, 五十嵐一, 石山敦士, 柳長門, 今川信作

    低温工学・超電導学会講演概要集   75th   248  2006.11

    J-GLOBAL

  • Numerical Simulation on Transient Thermal Characteristics of Cryocooler-cooled YBCO Coil

    ISHIYAMA Atsushi, ANDO Taketoshi, BANBA Sadanori, UEDA Hiroshi, FUJI Hiroshi, SAITOH Takashi, SHIOHARA Yuh

      75   189 - 189  2006.11

    CiNii

  • Visualization of Normal-zone Initiation and Propagation in YBCO Coated Conductor using Fluorescent Paints

    ISHIYAMA Atsushi, TSUCHIYA Motokazu, UEDA Hiroshi, KATO Hideyuki, NARA Koichi, SHIOHARA Yuh

      75   165 - 165  2006.11

    CiNii

  • Repetition strain characteristic of YBCO tapes

    BAMBA Sadanori, ANDO Taketoshi, UEDA Hiroshi, AGATSUMA Koh, ISHIYAMA Atsushi, IIJIMA Yasuhiro, SAITOH Takashi

      75   126 - 126  2006.11

    CiNii

  • Transient stability characteristics of parallel-connected YBCO coated conductors supposing power transmission cable : 2. Simulation

    ISHIYAMA Atsushi, IWATA Takuya, WANG Xudong, UEDA Hiroshi, MUKOYAMA Shinichi, SHIOHARA Yuh

      75   300 - 300  2006.11

    CiNii

  • Continuous Observation of Mice Heart Activity by μ SQUID System

    KAKO Masahiro, KIMURA Takeshi, KAMIYAMA Hiromi, KASAI Yusuke, ISHIYAMA Atsushi, ONO Yumie, KASAI Naoko

      75   18 - 18  2006.11

    CiNii

  • Over-Current Characteristics of Superconducting Model Cable using YBCO Coated Conductor

    UEDA Hiroshi, IWATA Takuya, WANG Xudong, ISHIYAMA Atsushi, MUKOYAMA Shinichi, SHIOHARA Yuh

      75   108 - 108  2006.11

    CiNii

  • Position Control of Active Magnetic Levitation using Sphere-shaped HTS bulk : simulation

    ISHIGAKI Yoshihiro, SUGA Kenji, UEDA Hiroshi, AGATSUMA Koh, ISHIYAMA Atsushi

      75   99 - 99  2006.11

    CiNii

  • Position Control of Active Magnetic Levitation using Sphere-shaped HTS bulk : experiments

    SUGA Kenji, ISHIGAKI Yoshihiro, UEDA Hiroshi, AGATSUMA Koh, ISHIYAMA Atsushi

      75   98 - 98  2006.11

    CiNii

  • MCG Measurement on Heart Activity of Mice

    KAKO Masahiro, KIMURA Takeshi, KASAI Yusuke, ONO Yumie, ISHIYAMA Atsushi, KASAI Naoko

    IEICE technical report   106 ( 139 ) 27 - 30  2006.06

     View Summary

    Disease-model mice generated by gene modification or administered of drug are provided to investigate the mechanism of heart disease development or treatment. We have developed a biomagnetic measurement system for mice with a high spatial resolution and enough magnetic sensitivity using a dc SQUID magnetometer, and we measured MCG on a normal mouse and a cardiac infarct model mouse more than once, and focused on the temporal change of heart activities. We found that the heart activity is weakening with time.

    CiNii

  • Degradation of YBCO tapes due to Over-current pulse drive

    ISHIYAMA Atsushi, WANG Xudong, UEDA Hiroshi, IIJIMA Yasuhiro, SAITOH Takashi, KASHIMA Naoji, MORI Masami, WATANABE Tomonori, MATI Takato, SHIOHARA Yuh

      2006 ( 16 ) 49 - 54  2006.06

    CiNii

  • 小動物用SQUID磁気計測システム

    石山敦士

    日本生体磁気学会誌 特別号 第21回日本生体磁気学会大会論文集   19 ( 1 ) 16 - 17  2006.06

  • マグネトメータを用いたMEG信号源推定 -その1 シミュレーションによる推定精度の検証-

    及川敬敏, 斎藤優, 葛西祐介, 木村壮志, 加古真祥, 神山拡己, 石山敦士, 葛西直子

    日本生体磁気学会誌 特別号 第21回日本生体磁気学会大会論文集   19 ( 1 ) 218 - 219  2006.06

  • マグネトメータを用いたMEG信号源推定 -その2 グラジオメータとの併用による推定精度の向上-

    斎藤優, 及川敬敏, 葛西祐介, 木村壮志, 加古真祥, 神山拡己, 石山敦士, 葛西直子, 渡邊裕, 河合毅師

    日本生体磁気学会誌 特別号 第21回日本生体磁気学会大会論文集   19 ( 1 ) 220 - 221  2006.06

  • 先見情報を用いないBeamformer法による複数信号源推定

    木村壮志, 加古真祥, 神山拡己, 及川敬敏, 葛西祐介, 斎藤優, 石山敦士, 葛西直子

    日本生体磁気学会誌 特別号 第21回日本生体磁気学会大会論文集   19 ( 1 ) 222 - 223  2006.06

  • 心疾患モデルマウスの心磁計測

    加古真祥, 中村祐, 木村壮志, 葛西祐介, 及川敬敏, 斎藤優, 神山拡己, 小野弓絵, 石山敦士, 葛西直子

    日本生体磁気学会誌 特別号 第21回日本生体磁気学会大会論文集   19 ( 1 ) 246 - 247  2006.06

  • 母親の心拍変動と胎児の心拍変動との関連解析 -音楽による影響-

    神山拡己, 葛西祐介, 白井健吾, 木村壮志, 加古真祥, 及川敬敏, 斎藤優, 石山敦士, 中居賢司, 福島明宗, 伊藤学, 葛西直子

    日本生体磁気学会誌 特別号 第21回日本生体磁気学会大会論文集   19 ( 1 ) 250 - 251  2006.06

  • The Measurement System of MCG on mice and MCG of Disease Modified Mice

    KAKO Masahiro, KIMURA Takeshi, ONO Yumie, ISHIYAMA Atsushi, KASAI Naoko, ODAWARA Akikazu

      2006 ( 43 ) 17 - 20  2006.05

    CiNii

  • A Criterion based on coil protection for determination of stabilizer thickness of YBCO coated conductors (1) : proposition of a criterion