AC LOSSES EVALUATION OF SILVER-SHEATHED BI-2223 TAPES WITH CONVERTING DC MAGNETIC FIELD ANGLE

A number of studies showed that the AC losses for B//c are much larger than that for B//ab due to the effects of I_c(B) behavior at 77K. We present the relation between AC losses and the orientations of DC magnetic field by a sample of Bi-2223 tapes with 37 filaments of a superconducting core, which were prepared by the powder-in-(Ag) tube (PIT). A universal formula on the relation between AC losses and the orientations of the DC magnetic field will be found out according to the ellipse model of the Norris equation. The formula will provide some useful hints for the theoretical analysis of AC losses.