AC SUSCEPTIBILITY AND AC LOSS IN Bi-2223/Ag SUPERCONDUCTING TAPES

摘要

The loss component of the susceptibility, x", of a monofilament Bi-2223/Ag tape in perpendicular ac magnetic field was measured as a function of temperature and ac magnetic field amplitude in the range from 0.02 to 7 mT at different frequencies in the range from 5 Hz to 5 kHz. The ac loss is composed of an eddy current loss in the silver sheath and a hysteretic loss in the superconductor core. The eddy current loss is calculated using Maxwell's equations by taking into account the magnetic field distribution in the superconductor core; this field is the sum of the applied field and the field generated by the shielding currents in the superconductor. The critical state model for a thin superconductor strip in a perpendicular field is used to predict the hysteretic loss. The theoretical calculations agree well with the experimental data.