Critical state in disk-shaped superconductors.

摘要: We have calculated the magnetic fields and currents occurring in a disk-shaped superconductor (radius {much gt}thickness) critical state self-consistent way using finite-element analysis. find that field shielded (or trapped) center of disk is roughly equal to {ital J}{sub c}}d, where d} thickness disk. The shielding also create radial which are or order c}}d/2 on surface. For low applied H}{sub appl}{lt}J{sub c}d these self-field effects dominate, leading deviation local direction from field, can exceed 90 deg towards outside perimeter If c}}d large, as case for YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} single crystals at 4.2 K, persist up several telsa field. dependence moment dominated regime independent whether c}} weakly strongly ({proportional to}1/{ital H}) dependent calculations were validated by comparison both resistive measurements section Nb{sub 3}Sn tape.