Magnetic shielding by Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7- delta / thick films

The magnetic shielding properties of YBCO thick-film shielding structures have been calculated using the Bean model, and these numerical results are compared to measured data. The numerical results were obtained with a three-dimensional finite-element code that performed a nonlinear, transient analysis of the superconducting material as a function of applied magnetic field. The superconducting properties of the Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7- delta / (YBCO) are included in this model by defining a nonlinear response of the high-temperature superconductor material to the applied field. The measurements were performed on superconducting, melt textured thick YBCO films deposited on cylindrical and planar substrates, which together formed a closed shielding structure. The YBCO shields were measured at various temperatures from 12 K up to T/sub c/. At 50 K these shields were found to completely shield a centrally placed magnetic probe up to an external field of 5 G.<
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