CRITICAL-CURRENT VERSUS FIELD BEHAVIOR IN AG BSCCO-2223 TAPES WITH DIFFERENT CRITICAL CURRENTS/

The dependence of J(c) upon applied magnetic field has been analysed i n BSCCO-2223 tapes with different geometrical structures of the superc onducting core. The samples. prepared by the PIT method, and rolled do wn to tapes of different thickness, were annealed up to three times wi th intermediate mechanical working. All measurements were carried out at 77 K, in magnetic field up to I T, applied both parallel and perpen dicular with respect. to the transport current. Several samples with t he same J(c) and different I-c and superconducting core thickness were measured and compared. All samples showed a qualitatively similar ''m emory effect'', with higher values of J(c) measured with decreasing ma gnetic field, but remarkable differences in the low fields regime, whe re thinner tapes (lower I-c) showed a faster decay of J(c) with B comp ared with the thicker ones. A simple semi-quantitative the self field of tapes, was well supported by tests carried out in a special experim ental arrangement so designed as to allow to characterize the ''true'' zero self-field behaviour of the material.