Analysis Of Critical Power Loss In A Superconductor

TL;DR

This paper analyzes how oscillating magnetic fields cause critical power loss in superconductors, affecting their breakdown field and cavity quality factor, with derivations for resistivity in different superconductor types.

Contribution

It provides a theoretical analysis of power dissipation and breakdown fields in superconductors under oscillating magnetic fields, including resistivity derivations for type I and II superconductors.

Findings

Breakdown field can be below Hc in some cases.

Cavity Q depends on Hp near H.

Resistivity expressions derived for fluxoid and normal regions.

Abstract

A critical power dissipation resulting from an oscillating magnetic field, Hp cos wt, can produce a magnetic breakdown field, H <Hc, the critical field of the superconductor. The analysis shows, for example, why the breakdown field of a superconducting microwave cavity can be well below Hc in some cases, and indicates what the functional dependence of the cavity Q may be for values of Hp near H . The effective resistivity of a single isolated oscillating fluxoid, as well as that of a stationary normal region, is also derived for both type I and type Il superconductors.