THE TRAPPED FIELD OF YBCO BULK SUPERCONDUCTING MAGNETS

We have measured trapped field distributions by scanning a Hall probe on various rectangular YBCO bulk superconductors and studied the effec ts of field dependence of J(c) bulk thickness and bulk size on the tra pped field. The trapped field could be increased by increasing the bul k thickness and size. However, a saturation was observed for the maxim um thickness. We also calculated the distribution of trapped field tak ing account of the field dependence of J(c). Experimental trapped fiel d distributions were in good agreement with our calculated values when we used the J(c)-B curves obtained from a d.c. magnetization measurem ent for samples. (C) 1997 Published by Elsevier Science Ltd.