# Backward superconducting switching

## Abstract

A discussion is given of the initial speeds at which superconducting material changes state according to the London electrody namics. These transitions are taken to occur in the form of phase boundary motions. Phase changes from the normal to the superconducting state and vice vena are considered for the cases in which the external magnetic field is radiated to the boundary of the superconducting material. A distinct difference is found in transition rates depending on whether tile transition is from the superconducting or from the normal state. In another case considered, the transition from normal to super is studied when the superconducting material is bounded by a good conductor. In all cases, constant critical field is taken as the switching criterion. The mathematical treatment involves the approximate solution of free boundary problems and mixed hyperbolic-parabolic boundary value problems.