2011 Fiscal Year Final Research Report
Control of electromagnetic phenomena in high Tc superconductor tapes to generate stable and uniform high magnetic fields by using high Tc superconductor magnets
| Project/Area Number |
21360132
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Power engineering/Power conversion/Electric machinery
|
|---|
| Research Institution | Kyoto University |
|---|
Principal Investigator |
AMEMIYA Naoyuki 京都大学, 大学院・工学研究科, 教授 (10222697)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Taketsune 京都大学, 大学院・工学研究科, 准教授 (30303861)
|
|---|
| Project Period (FY) |
2009 – 2011
|
| 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 |
|---|
| 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.
|
