Charging process simulation of a coil by a self-regulating high-Tc superconducting flux pump

Abstract

Self-regulating high-temperature superconducting (HTS) flux pumps enable direct current injection into a closed-loop superconducting coil without any electrical contact. In this work, the process of charging a coil by a self-regulating HTS flux pump is examined in detail by numerical modeling. The proposed model combines an $H$-formulation finite element method (FEM) model with an electrical circuit, enabling a comprehensive evaluation of the overall performance of self-regulating HTS flux pumps while accurately capturing local effects. The results indicate that the proposed model can capture all the critical features of a self-regulating HTS flux pump, including superconducting properties and the impact of the secondary resistance. When the numerical results are compared to the experimental data, the presented model is found to be acceptable both qualitatively and quantitatively. Based on this model, we have demonstrated how the addition of a milliohm range, normal-conducting secondary resistance in series with the charging loop can improve the charging process. In addition, its impact on the charging performance is revealed, including the maximum achievable current, charging speed, and the generated losses. The modeling approach employed in this study can be generalized to the optimization and design of various types of flux pumps, potentially expediting their practical application.