AC losses due to magnetic fields and transport currents

The AC losses in a superconductor subjected both to an applied field and transport current may be considered as the losses of two power supplies, one providing the field the other driving the transport current, to the HTS sample. We present a brief justification of our method to measure these losses and then give the results of simultaneous measurements of the losses of both these power supplies to an HTS tape in an AC applied field and carrying an AC or DC transport current. The magnetic losses for the case of field applied perpendicular to the tape face are shown to be very much larger than for the field parallel case, but both are small compared to the transport losses in the regions of field and currents of practical interest (i.e. when the superconductor is carrying currents comparable to the critical current).