Modelling, designing and improving scalable HTS magnetic screens for rotating machines

In this communication, we present a simple finite element model that allows designing and notably improving the scalability of high-temperature superconducting (HTS) magnetic screens used for attenuating the stray fields of large rotating machines. This work focuses on the case of an HTS racetrack coil serving as rotor pole of a wind turbine. Measurements show that the inhomogeneous field produced by this HTS coil can be approximated by a 2D finite element model. The model is used to highlight the main routes for the flux lines meandering around the superconductors to reach the region to be protected. Various ways to increase the reluctance of these routes are presented, thereby improving the field attenuation.
Further refinements of the model are then discussed to reproduce the anisotropic behavior of stacked tapes using recent formulations developed for foil windings.