INTERGRANULAR AND INTRAGRANULAR CURRENT DISTRIBUTION IN SINTERED YBCOFROM TRANSPORT AND INDUCTIVE MEASUREMENTS

The magnetization of and voltage drop across a superconducting YBCO wi re were measured when an a.c. current, whose maximum amplitude was bel ow the critical current, was flowing through the wire. Experimental re sults are interpreted assuming that the wires were made of two superco nducting phases; that in each phase, the current density depended on t he inner magnetic field according to the Kim-Anderson relation; and th at the current distribution inside the wire was such that the variatio n of the overall magnetic field proceeded from the outer part of the s uperconductor toward the center (critical-state model). It was possibl e to fit very well the results of both measurements with a single set of values for the model parameters.