THE CRITICAL-CURRENT IRREVERSIBILITY OF BI(2223) AG TAPE AND ITS MODIFICATION/

The critical currents of Bi(2223)/Ag tape at magnetic fields up to 2.5 T have been measured at different field orientations. The I-c values depend on the history of magnetic fields. This phenomenon can be expla ined in terms of irreversibility of the effective magnetic field cause d by the induced persistent current and the screening persistent curre nt. If the mean of the increasing and the decreasing applied field (H( a)p)), defined as the effective field (H-eff), is linearly related to the applied field, i.e. H-eff = alpha+beta H-ap, using H-eff instead o f H-ap, the modified I-c(H) curves curves are obtainable.