Numerical analysis of magnetization AC losses in high-temperature superconducting slabs subjected to uniform strains

Abstract

High-temperature superconductors in superconductor apparatuses are subjected to mechanical strains under operating conditions. These strains cause the degradation of the critical current densities and influence AC losses in the superconductors. Based on the dynamic process of thermomagnetic interaction, we report the results of numerical analysis of AC losses in an infinite high-temperature superconducting slab subjected to a uniform in-plane strain in an alternating external magnetic field parallel to the sample surface. The numerical analysis shows the details of electromagnetic phenomena in the slab and the dependences of AC loss on various external parameters including the uniform strain in the slab and the amplitude and frequency of the external magnetic field. In this paper, we find that whether the magnetic field fully penetrates the superconductor is the key factor that influences the features of AC loss. When the magnetic field cannot fully penetrate the superconductor, the loss rises with increasing strain or decreasing frequency. When the magnetic field can fully penetrate the superconductor, the feature is just opposite. We also analyze the effects of periodic strain on AC loss. It is interesting to find that when the periodic strain frequency equals the external magnetic field frequency, the AC loss reaches the maximum, regardless if the magnetic field fully penetrates the superconductor or not.