Comparison of transport and magnetic AC losses in HTS tapes

Losses in hts tapes due to transport currents are usually measured by a direct electrical contact method, losses due to applied magnetic fields are measured by winding 'pick-up' coils around the tape. In published data the contact method yields results up to two orders of magnitude lower for the same field. In this paper we show that the different "losses" are simply due to the differences in magnetic field penetration into the superconductor and the way in which its changes are recorded by the measurement circuit. We present data on losses due to applied magnetic fields in which the magnetic field penetration can be made to more closely reproduce that produced by a transport current. In this case the magnetic and transport losses are in good agreement.