J-A Approach to Simulations of HTS Tapes: How to Couple With Electric Circuits

The J-A formulation, or approach, is a set of differential equations that allow simulations of superconducting devices with A-formulation based modeling without the need to use conductivity, which may cause numerical stability problems in finite element solvers. In this paper, a method to couple the J-A approach to electric circuits is presented and discussed. A simple test case of a single tape connected to a circuit is used as a benchmark. Two strategies of physical representation of superconducting tapes are explored. The first, and the simplest, is the approximation of the tape as a thin-film, considering only the superconducting layer. The second strategy applies the thin-film approximation to the entire tape, in order to fully represent the magnetic field of the tape. The AC losses, current density and total current results of both strategies are directly compared to results obtained with the well-established T-A formulation. It is found that all results are totally compatible. The J-A approach is proving to be an interesting alternative if faster computational times are needed in 2D simulations.