Flux jumps at pulsed field magnetization

Abstract

Flux jumps lead to 10-20 times reduction of the shielding currents at a pulsed field magnetization of a melt-grown HTS annuli. The induced circular currents and the related trapped field are small after a field pulse since the duration of the pulse is shorter than the temperature relaxation time (<<1 s). Moreover, the residual trapped field in the hole of the annuli has the opposite direction in respect to the applied field. It is shown that the small value of the induced circular currents at the relatively high average critical current density is related to a narrow angular region of the flux motion (approximately 7 deg).