Critical states of a superconducting slab subjected to tension and bending

Abstract

This work is an extension of a previous critical-state model proposed by the same author [Li and Gao, SuST (2015)]. We want to show the evolution of critical states for a rather long time, and the physics behind the evolution is also desired. It is another purpose to make clear the role of mechanical deformation played in the evolution process of critical state. We thus develop the model with two new features: (a) mechanical loads are applied to both ends of the slab, instead of no external force applied in the previous model; (b) the critical current density is now a function of position, rather than a constant over the slab volume as in the previous model. The new results by the model consist of: (a) the evolution with time for a given strain value is generally the same as the strain-free case; (b) stretching accelerates the development of the critical state, and bending has no significant effect on the critical state; (c) the detailed critical-state profiles may provide how to regulate the electromagnetic field by strain in a superconducting device with slab geometry for practical purpose.