Generalized critical-state model of type II superconductors

Abstract

A modified form of the critical-state model of type II superconductors is described which takes account of H_c1 and surface sheath currents. The penetrating flux, hysteresis loop characteristics, a.c. losses and rate of penetration of flux into the superconductor when exposed to a sinusoidal magnetic field are evaluated. The model implies zero power dissipation for peak applied fields less than H_c1+ΔH and rapidly increasing dissipation just above this region, asymptotically approaching that derived from the Bean-London model.