AC HYSTERESIS LOSSES IN MONOFILAMENTARY PB-BI-SR-CA-CU-O/AG TAPES

The intergranular and intragranular hysteresis losses of two monofilamentary PbBiSrCaCuO/Ag superconducting tapes in perpendicular magnetic fields between 5 mT and 5 T were determined at T = 5 K and 77 K by measuring with a SQUID magnetometer the areas under the magnetization loops. By severely bending the tapes, the intergranular losses were eliminated. The intergranular hysteresis loss was modelled using equations for the magnetization of a thin superconducting strip in a perpendicular field while the intragranular loss was described by the Bean-model formulas for grains. The intergranular loss was found to be larger than the intragranular loss but much smaller than the AC loss of copper at 50 Hz. Measurements and calculations of the remanent magnetization of the tape were used to gain insight into the interdependence of the intergranular and intragranular critical current densities.