AC power losses in flexible thick-film superconducting tapes

Eddy current AC power loss in the metal and hysteresis loss in the superconductor of a metal-superconductor strip, such as the hastelloy-Y123 flexible tape, are calculated analytically in the low frequency limit. Cases studied are (i) where an AC magnetic field is applied perpendicular to the tape, (ii) where an AC field is applied parallel to the tape and (iii) where an AC current is applied to the tape. The losses are smallest in case (ii) while the losses in case (i) and (iii) show an approximate scaling. In cases (i) and (iii) the eddy current loss becomes important in high AC fields or al high AC currents, respectively, while in case (ii) the eddy current loss becomes important at high fields and at low fields, but less important at moderately strong fields. Because of the large resistivity of the hastelloy, the eddy current loss of a typical hastelloy-Y123 flexible tape can be neglected at frequencies below 100 Hz for all practical AC applications and the hysteresis loss in the superconductor is the only loss. (C) 1997 Elsevier Science B.V.