Trapped field and temperature rise in rectangular-shaped HTSC bulk magnetized by pulse fields

A rectangular-shaped GdBaCuO bulk (33 × 33 × 20 mm3) has been magnetized by pulse fields with various strengths from Bex = 3 T to 7 T at 44 K and 20 K. The time dependences of the local fields and temperatures have been measured at five positions on the bulk surface. The flux movement, flux trapping and the heat generation are closely related for lower applied fields, i.e., the temperature rise is larger at the specified positions, where a large number of magnetic fluxes are trapped. The heat generation is mainly due to the pinning loss in this condition. The maximum trapped field BT = 4.0 T can be realized on the bulk surface by a modified multi-pulse technique with stepwise cooling (MMPSC) method, on which BT reaches only 2.5 T at 20 K for a single pulse application.