DEPENDENCE OF SELF-FIELD AC LOSSES IN AC MULTIFILAMENTARY COMPOSITES ON PHASE OF EXTERNAL AC MAGNETIC-FIELD

We have measured the self magnetic field AC losses of a typical AC multifilamentary superconducting wire in an AC transverse external magnetic field at 50 Hz. The experimental results show that the self field AC losses are much higher than the transverse field AC losses and strongly depend on the phase difference between the transport current and the background field. We derived a theory to estimate the dependence of the self field AC losses on the phase of the external field based on the critical state model. In the paper, the measured loss characteristics are compared with the theoretical results. The theoretical model well explains the measured loss characteristics.