Distribution of the sheet current in a magnetically shielded superconducting filament

TL;DR

This paper theoretically investigates how a nearby magnet influences the current distribution in a superconducting filament, revealing current depression and enhancement effects dependent on magnet proximity and permeability.

Contribution

It derives and numerically solves an integral equation for current distribution in a superconducting filament near a magnet, highlighting the effects of magnetic shielding.

Findings

Current is depressed on the magnet-facing side and enhanced on the opposite side.

Significant current redistribution occurs even at low magnet permeability with short distances.

Saturation of current redistribution effects occurs at moderate permeability levels.

Abstract

The distribution of the transport current in a superconducting filament aligned parallel to the flat surface of a semi-infinite bulk magnet is studied theoretically. An integral equation governing the current distribution in the Meissner state of the filament is derived and solved numerically for various filament-magnet distances and different relative permeabilities. This reveals that the current is depressed on the side of the filament adjacent to the surface of the magnet and enhanced on the averted side. Substantial current redistributions in the filament can already occur for low values of the relative permeability of the magnet, when the distance between the filament and the magnet is short, with evidence of saturation at moderately high values of this quantity, similar to the findings for magnetically shielded strips.