Improvement in Magnetic Shielding by Use of a Triple-Cylinder Configuration of Superconducting BPSCCO
The critical current density (J c ) of high critical temperature (T c ) superconductors is very important parameter in magnetic shielding. However, it is difficult to fabricate a high-J c superconducting chamber. Therefore, the present authors have improved the magnetic shielding effects of high-T c superconducting cylinders. The magnetic shielding effect has already been improved by use of a double-cylinder constructed of a high-T c superconducting material. Furthermore, investigations were carried out with a superimposed triple-cylinder constructed of three BPSCCO cylinders. The value of maximum shielded magnetic flux density (B s ) for the triple-cylinder was found to be improved by several times that of the BPSCCO double-cylinder. The values of B s for the innermost and middle cylinders of the triple-cylinder have been analyzed by the use of critical state models. From the results of the experiments, an important criterion for the design of the magnetic shielding chamber was found. The authors also observed the periodic dependence of the DC-SQUID voltage on the applied magnetic field in the center of the BPSCCO triple-cylinder. Use of the triple-cylinder configuration was found to be very effective for magnetic shielding on the order of the flux quantum.
KeywordsCritical Current Density Flux Quantum Cold Isostatic Press Magnetic Shield Periodic Dependence
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