CRITICAL-STATE AND AC LOSSES IN MULTIFILAMENTARY BISRCACUO-2223 AG TAPES STUDIED BY TRANSPORT AND MAGNETIC MEASUREMENTS/

AC losses in two multifilamentary BiSrCaCuO-2223/Ag tapes differing in number of filaments were determined by transport and magnetic measure ments. In the latter, the AC field was directed perpendicularly to the wide side of the tape and the model of a superconducting strip was us ed in the calculations, Comparison of the experimental data with theor etical models confirmed that when the tape carries a transport AC curr ent, strong electromagnetic coupling between filaments leads to non-un iform distribution of current among the individual filaments, On the c ontrary, the results of magnetic measurements were consistently explai ned only if we supposed a negligible electromagnetic coupling between filaments, This effect could explain the commonly observed discrepancy between AC transport and magnetic loss measurements. By taking this e ffect into account, the apparent lack of consistency in the J(c) value of the superconductor derived from transport and magnetic experiments disappears. (C) 1997 Elsevier Science B.V.