| Project/Area Number |
21360132
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Power engineering/Power conversion/Electric machinery
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| Research Institution | Kyoto University |
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Principal Investigator |
AMEMIYA Naoyuki 京都大学, 大学院・工学研究科, 教授 (10222697)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Taketsune 京都大学, 大学院・工学研究科, 准教授 (30303861)
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| Project Period (FY) |
2009 – 2011
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| Project Status |
Completed (Fiscal Year 2011)
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| Budget Amount *help |
¥17,680,000 (Direct Cost: ¥13,600,000、Indirect Cost: ¥4,080,000)
Fiscal Year 2011: ¥5,980,000 (Direct Cost: ¥4,600,000、Indirect Cost: ¥1,380,000)
Fiscal Year 2010: ¥6,370,000 (Direct Cost: ¥4,900,000、Indirect Cost: ¥1,470,000)
Fiscal Year 2009: ¥5,330,000 (Direct Cost: ¥4,100,000、Indirect Cost: ¥1,230,000)
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| Keywords | 超伝導マグネット / 高温超伝導 / NMR/MRI / 電磁現象 / ツイスト / 磁界精度 / 遮蔽電流 / 残留磁化 / NMR / MRI / 加速器 |
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| Research Abstract |
The shielding-current-generated magnetic field deteriorates the field quality in the NMR magnets or the MRI magnets. The magnetic field generated by a small coil wound with a Bi-2223 tape was measured to study the influence of the shielding-current-generated magnetic field on the field quality of the coil. When changing the excitation current, an apparent hysteretic behavior was observed : this is the evidence of the influence of the shielding-current-generated magnetic field, the magnetization, on the generated magnetic field. When the coil current was kept at constant for six hours, a drift was observed in the measured magnetic field. This drift should be caused by the relaxation of the tape magnetization. We considered the application of a twisted Bi-2223 tape to reduce the micro-scale electromagnetic phenomena, that is, the shielding-current-generated magnetic field, to improve the field quality. Another coil was wound using a twisted Bi-2223 tape, and the magnetic field hysteresis and the stability of the magnetic field were studied experimentally. As compared to the coil wound with the non-twisted Bi-2223 tape, the coil wound with the twisted Bi-2223 tape showed a smaller hysteresis in the generated magnetic field and showed a better temporal stability of the magnetic field. Through numerical electromagnetic field simulation, we visualized the micro-scale electromagnetic phenomena and studied the field stability of magnets. Increase in the glass-liquid transition magnetic field and increase in the glass-liquid transition temperature of high Tc superconductor tapes might be an approach to control the micro-scale electromagnetic phenomena and to improve the field stability of magnets.
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