QUASI-STATIC MAGNETIC-BEHAVIOR OF A DISC-SHAPED TYPE-II SUPERCONDUCTOR

The isothermal, quasi-static, magnetic behaviour. including the intern al field and flux distribution profiles and the bulk magnetisation of reversible (i.e. pin-free) and irreversible disc-shaped type II superc onductors, in perpendicular applied field, are obtained from a rigorou s theoretical treatment which explicitly includes the constitutive B[H -rev] relation and the vortex pinning force dependence on induction B. The iterative numerical procedure to obtain the critical state is des cribed and calculations an made for the magnetic behaviour in thr low- re (niobium) and in the high-T-c, high-kappa (BSCCO) systems with vari ous vortex pinning models. Particular calculations are also made for c omparison with experimental magnetisation data on pure (almost pin-fre e) single crystal niobium disc specimens and for the 'arrow-head' effe ct. and for the vortex-lattice 'melting' transition in a BSCCO disc-sh aped single crystal. (C) 1997 Elsevier Science B.V.