Calculation of AC losses in large HTS stacks and coils

In this work, we present a homogenization method to model a stack of HTS tapes under AC applied transport current or magnetic field. The idea is to find an anisotropic bulk equivalent for the stack of tapes, where the internal alternating structures of insulating, metallic, superconducting and substrate layers are reduced while keeping the overall electromagnetic behavior. Our work extends the anisotropic bulk model originally presented by Clem et al. and later refined by Prigozhin and Sokolovsky. We disregard assumptions upon the shape of the critical region and use a power law E-J relationship allowing for overcritical current densities to be considered. The method presented here allowed for a computational speedup factor of up to 2 orders of magnitude when compared to full 2-D simulations taking into account the actual structure of the stacks without compromising accuracy.