Macroscopic numerical evaluation of heat generation in a bulk high Tc superconductor during pulsed field magnetization

Abstract

Pulsed-field magnetization of a bulk high Tc superconductor (HTS) is evaluated by using a macroscopic numerical simulation code. Local heat generation in the HTS during the pulsed-field magnetization is discussed to clarify the dynamic magnetization process. Nonlinear dependence of shielding current on the dynamic magnetic field is considered by using the flux flow-creep model. Dependence of flow resistivity on the magnetic field and temperature are also evaluated with the Bardeen-Stephen and the Tinkham models. It is numerically confirmed that reported experimental results are due to a decrease of the shielding current caused by local heat generation.

Flux Jumps at Pulsed Field Magnetization

“…This value is approximately two time smaller than the resistivity in the ab-plane at the normal state [11]. The region of flux motion remains at the high temperature after the flux jump due to the short pulse duration compared to the thermal relaxation time.…”

Local measurements of the magnetization process of bulk superconductors induced by a pulsed magnetic field

“…From application perspective, pulse field magnetization (PFM) is more feasible because a large current has to be fed only for a very short time and the magnetizing coil can be made small [2; 3]. PFM is, however, less effective than the FC method because of the heat that is generated by the dissipative motion of flux lines [2][3][4][5][6]. Most significantly, the difference in the trapped field with the FC method tends to escalate when the ability of trapping flux lines increases by improving the material characteristic or by decreasing the temperature.…”

YBCO bulks for preparation of permanent magnets

“…It is known, that in the case of pulse magnetization, there is an optimum magnetization flux density amplitude, beyond which there is a decay of the trapped flux attributed to the critical current decrease due to local heating. 15,16 For our material compositions and geometries, this amplitude of source field have been found to be 0.2 T.…”