Dynamic resistance and dynamic loss in a ReBCO superconductor

Abstract

Abstract Dynamic resistance is a time-averaged direct current (DC) resistance in superconducting materials, which typically occurs when a superconductor is carrying a transport DC while simultaneously subject to a time-varying magnetic field. Dynamic resistance has recently attracted increasing attention as it not only causes detrimental dynamic loss in superconducting devices such as the nuclear magnetic resonance magnets and superconducting machines, but on the other hand, the generated dynamic voltage can be exploited in many applications, e.g. high temperature superconducting (HTS) flux pumps. This article reviews the physical mechanism as well as analytical, numerical modelling, and experimental approaches for quantifying dynamic resistance during the last few decades. Analytical formulae can be conveniently used to estimate the dynamic resistance/loss of a simple superconducting topology, e.g. a single rare-earth-barium-copper-oxide tape. However, in a complex superconducting device, such as a superconducting machine, the prediction of dynamic resistance/loss has to rely on versatile numerical modelling methods before carrying out experiments, especially at high frequencies up to the kHz level. The advantages, accuracies, drawbacks, and challenges of different quantification approaches for dynamic resistance/loss in various scenarios are all inclusively discussed. The application of dynamic resistance in HTS flux pumps is also presented. It is believed that this review can help enhance the understanding of dynamic resistance/loss in superconducting applications and provide a useful reference for future superconducting energy conversion systems.