In this paper, the use of magnetic materials to divert flux in high-temperature superconductor superconducting coils and reduce transport ac loss is investigated. This particular technique is preferred over other techniques, such as striation, Roebel transposition, and twisted wires because it does not require modification to the conductor itself, which can be detrimental to the properties of the superconductor. The technique can also be implemented for existing coils. The analysis is carried out using a coil model based on the H formulation and implemented in comsol multiphysics. Both weakly and strongly magnetic materials are investigated, and it is shown that the use of such materials can divert flux and achieve a reduction in transport ac loss, which, in some cases, is quite significant. This analysis acts to provide a foundation for further optimization and experimental work in the future.
Ainslie, M. D., Yuan, W., & Flack, T. J. (2013). Numerical analysis of AC loss reduction in HTS superconducting coils using magnetic materials to divert flux. IEEE Transactions on Applied Superconductivity, 23(3), . https://doi.org/10.1109/TASC.2012.2227639