High magnetic field trapping in monolithic single-grain YBa2Cu3O(7-delta) bulk materials

Results of our study on high magnetic field trapping in unirradiated, high quality monolithic single-grain YBa2Cu3O(7-delta) disks are reported. A record high 4 T trapped field at the surface of the unirradiated disks is observed. However, below 11 K, large flux avalanches caused by thermal instability severely limit the remnant trapped field. Therefore, flux avalanche, rather than Jc x d, dictates the maximum trapped field at low temperatures. To overcome this problem, a strong high temperature superconductor trapped field magnet is proposed. A novel application of the avalanche effect is also mentioned.