Time evolution and spatial distribution of temperature in YBCO bulk superconductor after pulse field magnetizing

The time evolutions of temperature rise DeltaT (t) after pulse field magnetizing have been measured on the surface of a cryo-cooled YBaCuO bulk superconductor. The temperature rise DeltaT increases with increasing pulse field strength, and a quite large temperature rise (DeltaT(max) similar to 18.8 K) is observed just before the trapped magnetic flux reaches the central region of the bulk. The epoxy resin, impregnated and coated to the bulk crystal for mechanical reinforcement, prevents the heat exhaust towards the cold stage of the refrigerator and it needs much time to recover its initial temperature. The spatial distribution of DeltaT (t) has indicated that the magnetic fluxes tend to enter into the bulk, avoiding the 4-fold growth sector boundaries of the bulk crystal.