ANALYSIS OF AVERAGE TRANSPORT CRITICAL-CURRENT DENSITY OF OXIDE SUPERCONDUCTORS DEPOSITED ON A SILVER BASE

Considering the resistivity of a silver base and the contact resistanc e of a silver base with a bulk superconductor, the dependence of avera ge critical current density J(c)(D,H-a) of a high-T-c, oxide supercond uctor deposited oil a silver base on the sample dimension D and the ap plied magnetic field H-a is calculated using a generalized critical-st ate model, which was recently extended to low field by Chen and Yang [ Physica C 224 (1994) 345]. The self-field effect of the average critic al current was also taken into account in the model. Based on the gene ralized critical state model, new behaviors of J(c)(D, H-a) in the low -field range of H-c1 less than or equal to H-a much less than H-c2 are obtained. In addition, a constant J(c)(D, H-a) for 0 less than or equ al to H-a less than or equal to H-c1 is obtained, which is different f rom the results derived from a model that does not include the self-fi eld effect. However, these theoretical results can be fitted to the ex perimental data to obtain some important macroscopic material paramete rs and may be used to interpret tile dimension effect of transport J(c ) of a high-T-c oxide superconductor deposited on a silver base.