The Bean model of the critical state in a magnetically shielded superconductor filament

TL;DR

This paper investigates how a coaxial soft-magnet sheath influences magnetic flux penetration and magnetization in a cylindrical type-II superconductor filament, revealing enhanced flux penetration fields and calculating related hysteresis losses.

Contribution

It introduces a model for flux penetration in a superconductor with a magnetic sheath using the Bean model, highlighting the sheath's effect on flux penetration and magnetization.

Findings

Magnetic sheath enhances the flux penetration field.

Magnetization of the heterostructure is significantly affected.

Hysteresis AC losses are quantified.

Abstract

We study the magnetization of a cylindrical type-II superconductor filament covered by a coaxial soft-magnet sheath and exposed to an applied transverse magnetic field. Examining penetration of magnetic flux into the superconductor core of the filament on the basis of the Bean model of the critical state, we find that the presence of a non-hysteretic magnetic sheath can strongly enhance the field of full penetration of magnetic flux. The average magnetization of the superconductor/magnet heterostructure under consideration and hysteresis AC losses in the core of the filament are calculated as well.