Dynamic resistance in horizontally parallel HTS tapes carrying DC transport currents under perpendicular AC magnetic fields

Abstract Dynamic resistance, which occurs when a second generation of high-temperature superconducting (HTS) tape carries DC transport current under an external AC magnetic field, can be critical issues for HTS applications. This manuscript presents an experimental and numerical study of the dynamic resistance in three parallel HTS tapes arranged horizontally in a perpendicular AC magnetic field. This study aims to clarify the effect of magnetic interactions between adjacent horizontal HTS tapes on dynamic resistance. The commercially available, 4-mm-wide HTS-coated conductors were fixed with 0.5 mm distance between neighboring HTS tapes. The magnetization loss of the single tape and the three parallel tapes was measured in advance to provide a reference. Then, the dynamic resistance of the tapes was measured with various DC transport currents ranging from 8.3 to 116 A under an AC magnetic field with an amplitude of up to 106 mT and a frequency of 72.73 Hz. A two-dimensional (2D) finite element modeling (FEM) simulation based on the T-A formulation is used to simulate the electromagnetic characteristics in COMSOL Multiphysics 6.2. It was experimentally confirmed that the effective penetration magnetic field obtained from the normalized magnetization loss curve is lower for the three-parallel tape than for the single tape. In addition, the threshold field of dynamic resistance for the middle tape of threeparallel tape is lower than that of the single tape, due to the strengthened field in the horizontal gap between each pair of the horizontally arranged tapes. The experimental results are in good agreement with those of a 2D-FEM that assumed a trapezoidal profile with a decreasing lateral distribution of the critical current density decreases over a width of approximately 500 μm from the edge. Electromagnetic analysis from the 2D-FEM successfully explains the behavior of dynamic resistance resulting from magnetic interactions with adjacent superconducting tapes. Our findings are a valuable reference for dynamic resistance/loss in HTS coil applications.