| Project/Area Number |
03805035
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
計測・制御工学
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
SASADA Ichiro KYUSHU UNIVERSITY,ASSOCIATE PROFESSOR, 工学部, 助教授 (20117120)
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| Co-Investigator(Kenkyū-buntansha) |
ENPUKU Keiji KYUSHU UNIVERSITY,ASSOCIATE PROFESSOR, 工学部, 助教授 (20150493)
SAKAMOTO Hiroshi KUMAMOTO INST.OF TECH.,LECTURER, 講師 (50225819)
HUNAKI Kazuo KYUSHU UNIVERSITY,ASSOCIATE PROFESSOR, 工学部, 助教授 (60091352)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1992: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1991: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | Magnetic Shield / High-Tc Superconductor / Trapped Flux / Trapped Flux Measurement / Fluxgate Magnetometer / Magnetic Shaking / Amorphous Magnetic Material / 強磁性体 / 低温用磁界センサ / 磁気シ-ルド |
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| Research Abstract |
The amplitude of the trapped flux in high-Tc superconductors is strongly affected by the frequency of the magnetic field applied during cooling and the cooling rate. The amplitude is small when the frequency is high or the cooling rate is low.For example,dc magnetic field was trapped in a BiSrCaCuO high-Tc superconducting bulk plate almost as it was;however,ac magnetic field of 10Hz was trapped 1/43 times as small as the amplitude applied to the sample.This nature of the trapped flux allows a new symbiotic combination of ferromagnetic shield with magnetic shaking and high-Tc superconducting magnetic shield.In this combination,the earth's field causing a trapped-flux problem can be attenuated to as small as 0.1mG by the ferromagnetic shield with magnetic shaking whereas any care to suppress the leakage of the shaking field is not needed,making the ferromagnetic shield very thin and lightweight.
A miniaturized fluxgate magnetometer(resolution as high as 0.46mG at 77K)is useful to measure the distribution of the trapped flux in high-Tc superconductors,in which,by encapsulating the tip of the core with a piece of copper,the specimen can be avoided to be exposed to high-frequency exciting field of the order of 1G whereas it is transparent to the trapped flux.
Amorphous magnetic material(Metglas 2705M)with highly rectangular B-H loop exhibits large enhancement of shielding performance by magnetic shaking which is 20-30 times better than Permally.
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