Dependence of dynamic resistances in high-temperature semiconducting quasi-isotropic strands on magnitude and orientation of AC magnetic field

Abstract

The dynamic resistance of a superconductor appears if it carries a direct current (DC) current and is simultaneously exposed to alternative current (AC) magnetic fields if its amplitude is higher than its full penetrated field. Due to its strong anisotropy, the dynamic resistance of high-temperature superconducting (HTS) tape is not only affected by the magnitude of AC magnetic fields but also their orientations. In particular, the dynamic resistance has considerable effect on the current distribution in HTS cables (except for Roebel cables) and even cable-in-conduit conductors made from those HTS cables, except for dissipative loss. This paper presents the behavior of dynamic resistance in an HTS quasi-isotropic strand (Q-IS), which consists of four sub-stacked 2G HTS tapes proposed by our group at North China Electric Power University, while it carries a DC current and simultaneously experiences an AC magnetic field with different magnitudes and orientations. An angular dependence of dynamic resistance in a single 2G HTS tape in an AC magnetic field with various orientations is first performed in simulations and experiments, respectively. The experimental results are in good agreement with the simulated ones, which shows that the dynamic resistance of a Q-IS also exhibits quasi-isotropic characteristics and has an important effect on the distribution of DC transport current. The related results are promising for the design and application of other DC HTS cables, feeders and magnets.