Critical state in Josephson junction arrays as models of a bi-dimensional superconducting granular system

In order to analyze the diamagnetic properties of sintered granular superconductors, a circuital model consisting of a network of identical inductances (L0) and Josephson junctions is developed. In particular, the case of sufficiently high values of the maximum Josephson currents (Ij), such that L0Ij≫Φ0, is considered. Neglecting thermal activation processes, the process of irreversible penetration of flux quanta is studied numerically. A critical state model follows. © 1993