Heat propagation analysis in HTSC bulks during pulse field magnetization

The time evolutions of the three-dimensional temperature profiles in a superconducting bulk disc have been calculated after applying a pulse field in the pulse field magnetization (PFM) by use of a finite element method (FEM). The total generated heat Q, experimentally estimated using the maximum temperature rise ΔT_max and specific heat C of the bulk, used in the analysis and the distribution of Q in the periphery region of the bulk, is suitably supposed in order that the calculated time evolutions of temperatures T(t) reproduce the measured ones on the bulk surface. From the analysis, the heat generation during PFM takes place under adiabatic conditions because the total Q value is about one or two orders of magnitude larger than the cooling power of the cryocooler used. The enhancement of the total heat capacity by setting a stainless steel ring onto the bulk as a heat reservoir is one of the effective methods to reduce the temperature rise and to enhance the trapped field.