Experimental determination of the losses produced by the interaction of AC magnetic fields and transport currents in HTS tapes

This paper presents the results of a comprehensive series of measurements by our newly developed calorimetric technique of the ac losses in high quality BSCCO-2223 tape. The measurements encompass the losses due to the simultaneous application of ac transport currents and ac magnetic fields of the same frequency; parallel or perpendicular to the tape. The variation of the losses with peak current, peak applied magnetic field and phase between current and field is reported. The results confirm our previously published work in that the losses can be estimated by assuming that only in the perpendicular field orientation do the self and applied fields interact and also that the equations previously developed for estimating losses hold for tapes with a wide range of critical currents. Based on these ideas we are able to suggest equations predicting the effect of a phase difference on losses which gives reasonable agreement with measurements.