Rise-Time Elongation Effects on Trapped Field and Temperature Rise in Pulse Field Magnetization for High Temperature Superconducting Bulk

Pulse field magnetization (PFM) using a magnetic pulse of B ex =3.83–5.53 T with various rise times t r (=6–20 ms) has been performed for the cryocooled SmBaCuO bulk superconductor starting at the initial temperature of 40 K. The time evolutions of temperature T ( t ) and local field B L P ( t ) have been measured on the bulk surface after applying the magnetic pulse. With increasing t r , the temperature rise Δ T and the trapped field B T P increase for B ex ≤4.70 T and decrease for B ex =5.53 T. The rise time t r required to realize the optimum B T P has been found to become longer for a smaller pulse field B ex . From the analyses of the generated heat Q after five successive applications of pulses (Nos. 1–5) with the same amplitude, the Q (No. 5) value, which can be regarded as the viscous loss Q v , decreases with increasing t r , due mainly to the decrease in the flux propagation velocity v in the bulk with longer t r .