Flux jumps at pulsed field magnetization

TL;DR

This paper investigates flux jumps in melt-grown HTS annuli during pulsed field magnetization, revealing their impact on shielding currents and trapped fields, and explaining the underlying flux motion mechanisms.

Contribution

It provides new insights into flux jump effects and the angular region of flux motion in HTS annuli under pulsed magnetization conditions.

Findings

Flux jumps cause significant reduction in shielding currents.

Residual trapped field in the hole opposes the applied field.

Flux motion is confined to a narrow angular region (~7 degrees).

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).