Modelling and comparison of in-field critical current density anisotropy in high temperature superconducting (HTS) coated conductors

Abstract

The development of high-temperature superconducting (HTS) wires is now at a stage where long lengths of high quality are commercially available, and of these, (Re)BCO coated conductors show the most promise for practical applications. One of the most crucial aspects of coil and device modeling is providing accurate data for the anisotropy of the critical current density Jc(B, θ) of the superconductor. In this paper, the in-field critical current density characteristics Jc(B, θ) of two commercial HTS coated conductor samples are experimentally measured, and based on these data, an engineering formula is introduced to represent this electromagnetic behavior as the input data for numerical modeling. However, due to the complex nature of this behavior and the large number of variables involved, the computational speed of the model can be extremely slow. Therefore, a two-variable direct interpolation method is introduced, which completely avoids any complex data fitting for Jc(B, θ) and expresses the anisotropic behavior in the model directly and accurately with a significant improvement in computational speed. The two techniques are validated and compared using numerical models based on the H-formulation by calculating the self-field and in-field dc critical currents and the ac loss for a single coated conductor.