The Effect of an Axial Moment on Normal-Phase Propagation in Type II Superconductors Carrying a Current
A heat pulse of suitable magnitude applied locally to a wire of a type II superconductor carrying a steady transport current will initiate a small normal region. This normal region will propagate along the conductor if the rate of generation of Joule heat ρJ2 is greater than the rate of heat flow to the outside and the neighboring region. The problem of the one-dimensional thermal propagation of this normal front has been studied by a number of workers.1,2 The propagation is due to the flow of heat from the normal volume, where heat is produced at a constant rate ρJ2, into the cooler superconducting region. The traveling superconducting—normal interface is taken to be at the critical temperature T c (H) characteristic of the applied field H. Measurements on bare wires of Nb—Zr alloys as a function of current and magnetic field’ showed that the velocity of propagation was approximately linear in the current density J and independent of the normal-state resistivity ρ n. The slope of velocity vs. J was found to depend mainly on the thermal capacity and the transition temperature T c (H) (hence on the magnetic field).
KeywordsMagnetic Energy Critical Moment Persistent Current Pure Vanadium Bare Wire
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