Browsing by Author "LEE, WD"

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ANALYSIS OF TRANSPORT CRITICAL-CURRENT DENSITY IN A BENT BI-PB-SR-CA-CU-O SILVER-SHEATHED TAPE
(1995-06-01)
LEE, WD
;
HORNG, L
;
YANG, TJ
;
CHIOU, BS
;
電子物理學系
The experimental results on the magnetic behavior of the transport critical current density in a bent Bi based superconducting tape have shown that the irreversible strain limit epsilon(irrev) for the onset of permanent strain damage to Ag sheathed superconductors is not dependent on the magnetic field, nor does the normalized I-c(H, epsilon)/I-c(0, epsilon) current depend on the strain at least up to 0.5 T at 77 K. Such a behavior has been attributed to two reasons: (1) The intrinsic pinning properties are unchanged in a bent tape; (2) The strain effect is extrinsic and arises from superconductor cracks. Thus, based on these arguments a Josephson junction tunneling model with cracks in between the grain boundaries is proposed to explain the J(c) behavior quite well for a bent granular high-T-c superconducting tape. Our model calculation shows that the critical current density of high-T-c superconductor may be enhanced by increasing the strain tolerance epsilon(irrev) and the epsilon(irrev) is determined by the properties of Ag sheathed tape and its related material parameters, which are dependent on the connectivity of the grain boundaries.
HYSTERETIC BEHAVIOR OF THE TRANSPORT CRITICAL-CURRENT DENSITY IN A BENT BI-PB-SR-CA-CU-O SILVER-SHEATHED TAPE
(1995-04-15)
LEE, WD
;
HORNG, L
;
YANG, TJ
;
CHIOU, BS
;
電子物理學系
MECHANICAL-PROPERTIES OF AG-SHEATHED BI-BASED SUPERCONDUCTING TAPES
(1993-12-01)
HORNG, L
;
CHEN, K
;
LEE, WD
;
WEI, JC
;
YANG, TJ
Flexible Ag-sheathed Bi-based superconducting tapes have fabricated by powder-in-tube technique. The critical current density (J(c)) does not varied when the bending radius is larger than the critical bending radius R0, bending radius without deteriorating transport properties. The bending tests were studied under magnetic field up to 5,000 G. The critical bending radius R0 (or Critical bending strain epsilon(b0)) was found to be independent of magnetic field from 0 to 5,000 G. The J(c)(B)/J(c)(0) curves are super-imposed in the same curve, i.e., the transport behavior of a tape at magnetic field is not affected by bending. It implies that the intrinsic pinning properties of a bent tape are unchanged in magnetic field. The results are useful for making a react-and-wind magnets and cables.