Effect of Stack Geometry on the Dynamic Resistance Threshold Fields for Vertical Stacks of Coated Conductor Tapes

Abstract

The expanding capabilities of HTS flux pumps and rectifiers to provide kA+ currents, necessitates the exploration of high current switching phenomenon. One such phenomenon, the dynamic resistance, occurs in type-II devices carrying dc transport currents while exposed to ac magnetic fields with an amplitude above some sample dependent threshold. In the following, finite element analysis of the threshold field for dynamic resistance in superconducting cables comprised of N tapes connected in parallel and stacked vertically is presented. Cables are modelled using the commercial software COMSOL and the H-formulation. The models employ Ic(B,θ) and n(B,θ) data obtained on short samples at 77K as inputs to more accurately reflect the variation in local properties within the superconductor. The finite element results are then compared with calculations made using analytical models assuming a critical state. The finite element data closely resembles that predicted for a strip for a single tape, rapidly tending towards the slab results as N increases.EPSRC Early Career Fellowship EP/ P020313/1 New Zealand MBIE Endeavour Grant no. RTVU1707 NZ Royal Society Marsden Grant no. MFP-VUW180

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