Effect of flux creep and viscous flux flow on flux-pinning-induced stress and magnetostriction in a long rectangular slab superconductor

Abstract

The magnetoelastic problem for a superconductor slab placed in a time-dependent magnetic field is considered. Two major components of the flux (vortex) motion: flux creep and viscous flux flow have been considered, among which the logarithmic dependence of activation energy on the current density is assumed for the creep problem. As one of the two parts of flux motion, viscous effect of flux flow dominates the motion of fluxoids at high flux velocities and enhances the maximum tensile stress and the magnetostriction remarkably after zero-field cooling. However, the effect of flux creep cannot be omitted at low magnetic field sweep rate (Ḃa) and is helpful to alleviate tensile stresses within the superconductor. Apart from this, the position (x0) where the maximum tensile stress occurs has a similar dependence on the sweep rate (Ḃa) as the stress value itself. All the results indicate that the sweep rate (Ḃa) should be considered in the magnetization process in order to avoid cracking within the superconductor slab.