Numerical calculations of the total ac loss of Cu-stabilized YBa2Cu3O7−δ coated conductor with a ferromagnetic substrate

Abstract

A numerical model is developed to calculate the total alternating-current (ac) loss of Cu-stabilized YBa2Cu3O7−δ (YBCO) coated conductors with a ferromagnetic substrate when carrying an alternating transport current in an ac background magnetic field. The time evolutions of current and magnetic field distributions along the width of the conductor are calculated by solving the one-dimensional Poisson equation for the magnetic vector potential. In addition to the ac loss dissipated in the superconducting layer, the ferromagnetic loss in the substrate and eddy current loss in the Cu stabilizer are also modeled. In the calculations, the superconducting voltage-current behavior is assumed to follow a power law. The model is capable of addressing other practical aspects of YBCO conductors, including the field dependence of the critical current density, and n value, and nonuniformities in the conductor. The magnetic shielding of the ferromagnetic substrate, however, was ignored in the calculations. Numerical results are compared with analytical and experimental results for some special cases.