On the flux jumps in the flux creep regime of type - II superconductors

TL;DR

This paper presents a theoretical analysis of thermomagnetic flux jumps in type-II superconductors within the flux creep regime, highlighting the sensitivity of stability thresholds to material and external parameters.

Contribution

It introduces a new stability criterion for flux jumps considering nonlinear current-voltage characteristics and heat flux diffusion effects.

Findings

Identified a threshold magnetic field for thermomagnetic instability.

Showed high sensitivity of flux jump stability to critical current density.

Demonstrated the influence of magnetic field sweep rate on flux stability.

Abstract

A theoretical study of dynamics of small thermal and electromagnetic perturbations in type-II superconductors in the flux creep regime with a nonlinear current-voltage characteristics is performed. For this purpose, the space-time evolution of temperature and electric field was calculated using the heat diffusion equation, coupled with Maxwell's equations and material law, assuming that the applied magnetic field is directed parallel to the surface of the sample. A threshold field $B_j$ for the occurrence of thermomagnetic instability has been found assuming that the heat flux diffusion is considerable faster than the magnetic flux diffusion in superconductor. The obtained stability criterion for the thermomagnetic flux jumps demonstrates the extremely high sensitivity of the threshold field on the values of the critical current density and external magnetic field sweep rate.