Superconducting trapped-field magnets: Temperature and field distributions during pulsed field activation

TL;DR

This paper models the temperature and magnetic field distributions in superconductors during pulsed-field activation, revealing optimal conditions for maximum flux trapping based on material properties and field ramp rates.

Contribution

It introduces a combined heat diffusion and critical state model to analyze flux trapping in superconductors during pulsed activation.

Findings

Maximum trapped flux occurs at an optimal applied field B_opt.

Trapped flux depends on material parameters and field ramp rate.

The model predicts temperature and field distributions during activation.

Abstract

We calculate the temperature and magnetic field distributions in a bulk superconductor during the process of pulsed-field magnetic activation. The calculations are based on the heat diffusion equation with account of the heat produced by flux motion, and the critical state model with temperature dependent critical current density. For a given activation time the total amount of trapped flux is maximum for an optimal value B_opt of the maximal applied field. We analyze how B_opt and the trapped flux depend on the material parameters and the field ramp rate.