THE AZIMUTHAL CRITICAL-STATE OF A SUPERCONDUCTING HOLLOW CYLINDER

We use the critical state model to calculate the flux profiles and mag netization curves for type II superconducting hollow cylinders of diff erent wall thicknesses subject to an azimuthal magnetic field produced by a coaxially arranged current-carrying wire. We analyze the cases o f field-independent and field-decaying critical current densities, and systematically compare the results with those expected for the ''conv entional'' slab geometry using parameters typical of a high temperatur e ceramic superconductor. Some new features are observed for the hollo w cylinder, such as the different shape and the asymmetry of the flux distribution profiles, as well as the strong increase of the full pene tration field and the field at which the magnetization curves have max ima, with the wall thickness. In our opinion, this feature is the one that should be compared with the experiment in order to test our resul ts. (C) 1997 Elsevier Science B.V.