Alternating current losses in stacked Bi2Sr2Ca2Cu3O10/Ag tapes in perpendicular magnetic fields

Alternating current losses in stacks of powder-in-tube-processed Bi2Sr2Ca2C u3O10/Ag tapes were measured in perpendicular magnetic fields and compared with calculated hysteresis losses based on the critical-state model. Four m ain factors had to be taken into account for the calculations of the losses : (1) the inclusion of the area of the Ag sheath in determining the critica l-current densities of the stacks, (2) the zero-applied-field critical curr ents I-c(perpendicular to)(0) with truly perpendicular fields only, not the standard self-field critical current I-c(S)(0), and (3) the field-dependen t critical current I-c(H), e.g., the Kim's model, and (4) the subtraction o f the frequency-dependent losses at very high fields. With these considerat ions, the agreement between the calculated and the measured values of the l osses is excellent for fields beyond the full-penetration fields. However, these factors did not totally account for the low-field losses. (C) 2000 Am erican Institute of Physics. [S0021-8979(00)04617-X].