Determination of critical current density from arbitrary flux relaxation process

TL;DR

This paper presents a method to determine the critical current density of a type-II superconductor from flux relaxation processes starting below the critical current, using a virtual time interval to convert the data.

Contribution

It introduces a novel approach to calculate critical current density from flux relaxation data initiated at sub-critical currents, expanding measurement options.

Findings

Critical current density can be derived from sub-critical flux relaxation.

A virtual time interval enables conversion of flux relaxation data.

Exact solutions for current density over time are provided.

Abstract

The current-carrying ability of a type-II superconductor is generally represented by its critical current density. This can be determined by measuring a flux relaxation process starting with a testing current density that is greater than or equal to the critical value. Here we show that a flux relaxation process starting with an intermediate current density can be converted into a process starting with the critical current density by introducing a virtual time interval. Therefore, one may calculate the critical current density from the flux relaxation process starting with a current density below the critical value. The exact solutions of the time dependence of current density in the flux relaxation process were also discussed.