Partial Homogenization Methods to Simulate HTS Tapes Using the H and T-A Formulations

Abstract

REBCO coated conductor tapes are a promising technology for developing high-field accelerator magnets since their increased current carrying capacity and operational temperature allows achieving higher-fields and current levels with higher thermal margin. Superconducting materials still present challenges associated with their non-negligible losses in transient conditions, hence, finite element analyses become essential to design feasible superconducting systems. The H formulation is known in literature for its accuracy, while the T-A formulation offers computational efficiency. Nonetheless, both methods remain computationally demanding, especially when the superconducting tapes are modelled considering the extreme aspect ratios of different materials in the layered tapes. Homogenized models have been proposed to reduce computational requirements, however, modelling all layers as a single domain can impose the current to flow through all conducting layers rather than only the REBCO layer, even when its resistivity is very low. This study presents a comparative analysis using the H and the T-A formulations for a partially homogenized model, where the superconducting layer is modelled independently from the remaining conducting layers, and a fully homogenized model. The models' accuracy for transport loss estimation in transient conditions is discussed and compared with experimental loss measurements for a REBCO tape powered with AC currents.