| Project/Area Number |
09650373
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | KYUSHU-SANGYO UNIVERSITY |
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Principal Investigator |
SAKAMOTO Nobuyoshi FAC.ENGINEERING,ELECTRI-CAL ENG., PROFESSOR, 工学部・電気工学科, 教授 (80069509)
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| Co-Investigator(Kenkyū-buntansha) |
AKUNE Tadahiro FAC.ENGINEERING,ELECTRI-CAL ENG., ASSOCIATE PROFESSOR, 助教授 (00104860)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1998: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1997: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | OXIDE SUPERCONDUCTOR / MAGNETIC RELAXATION / HIGH-TEMPERATURE MAGNETIZATION / PIN POTENTIAL / ピンポテンシャル / 酸化物超伝導体 |
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| Research Abstract |
Barrier height for the flux creep increases with the temperature T, although the pinning potential is expected to decrease with increasing T.This anomaly was explained qualitatively by Welch by means of nonlinear potential barrier U(J) where the current J around which the analysis is centered decreases at high T and accordingly the nonlinearity leads to high pinning barrier energy at high T.To confirm this mechanism, U(J) relation of a wide range of J is required. By cooling a superconductor magnetized at higher temperature T_0 + DELTAT to an operating temperature T_0(High-Temperature Magnetization : HTM), low magnetization current J states equivalent to those after long-time creep are realized. The combination of the HTM method and the HaIl voltage measurement attached to YBaCuO superconductor gives the magnetic relaxation curve in a wide range of J.These creep curves are analyzed in details with the simulation based on the creep equation. The observation-window is enlarged by HTM method and the nature of the current dependent pinning potentials is discussed.
Simulation of the flux creep is performed and compared with the magnetic relaxation after hightemperature magnetization.
1. From short-time observations after HTM, offset creep curves equivalent to several months creep characteristics are obtained by smoothly connecting each creep curve after HTM.
2. Simulated characteristics are favorably compared with both the suppressed creep curves after HTM and the offset creep curves.
3. The potential depth U_0 estimated from the offset creep curves shows that U_0 increases as the temperature reduces.
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