TEION KOGAKU (Journal of Cryogenics and Superconductivity Society of Japan)
Online ISSN : 1880-0408
Print ISSN : 0389-2441
ISSN-L : 0389-2441
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Volume 53, Issue 4
Displaying 1-5 of 5 articles from this issue
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Preface
Focused Reviews
  • Magnetic Field Stability of Superconducting Magnets Using External Power Supplies for NMR/MRI
    Masato TAKAHASHI
    2018 Volume 53 Issue 4 Pages 203-209
    Published: July 20, 2018
    Released on J-STAGE: August 03, 2018
    DOIhttps://doi.org/10.2221/jcsj.53.203
    JOURNAL FREE ACCESS
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    The magnetic field stability of superconducting magnets powered by external power supplies has been investigated. The magnetic field fluctuation caused by current fluctuation generated in the external power supply is classified according to its frequency and range. Superconducting magnets for high-resolution NMR (Nuclear Magnetic Resonance) require one of the highest stability in the variety of application. It is demonstrated that high temperature superconducting magnets in driven mode can be applicable for high-resolution NMR. Such kind of technology will also be used for the future field swept NMR of quadrupolar nuclei which is now being developed.

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  • Power Supply System for Exciter-driven Operation of HTS-MRI
    Yasuyuki SHIRAI, Shoichi YOKOYAMA
    2018 Volume 53 Issue 4 Pages 210-217
    Published: July 20, 2018
    Released on J-STAGE: August 03, 2018
    DOIhttps://doi.org/10.2221/jcsj.53.210
    JOURNAL FREE ACCESS
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    We have been developing a conduction cooled HTS-MRI that is driven by a power supply in order to solve the long-lasting attenuation of the screening current induced on superconducting tapes at the time of initial excitation and the difficulty with REBCO tape superconducting junctions, as well as a superconducting switch for persistent current operation. A power supply system consisting of two exciters, one for charging and discharging and the other for holding the magnet current, is proposed and developed. The supply system is equipped with a control block to compensate the magnetic field deviation caused by the screening current. We carried out a magnetic field stability experiment using a 32-H HTS-MRI magnet excited by the power supply system proposed which was equipped with specially designed micro-current control.

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