Role of asymmetric critical current on magnetization loss characteristics of (RE)Ba2Cu3O7-d coated conductors at various temperatures

Commercial high-T-c superconducting (HTS) coated conductors exhibit asymmetric I-c(B,theta) characteristics, where B presents a DC magnetic field and theta is defined as the angle between an applied magnetic field and the normal component of the superconductor plane. The asymmetric I-c(B,theta) characteristics have a non-trivial influence on the dominant loss component, magnetization loss, of various HTS applications where HTS conductors are exposed to an AC magnetic field. Here, we present measurements of I-c(B,theta) and magnetization loss in a 12 mm-wide (Rare Earth)Ba2Cu3O7-d (REBCO) commercial coated conductor at 77, 70, and 65 K. In the I-c(B,theta) measurement,. was varied around a full 360 degrees revolution and B was varied up to 0.2 T. In terms of the magnetization loss measurement, the applied AC magnetic field amplitude is up to 110 mT and the field angle varied from 0 degrees to 180 degrees. At the three given temperatures, we observed magnetization loss variations among the field-angle range, in particular, for theta and 180 degrees-theta, which are in mirror symmetry relative to the superconducting plane. Furthermore, this asymmetric field-angle dependence of the magnetization loss becomes more apparent at higher applied field amplitudes and lower operating temperatures. A finite element method simulation using H-formulation was carried out by directly interpolating the measured I-c(B,theta) data, and the simulation results reproduce the trend of the experimental results. We also found that the magnetization loss is not equivalent within the positive and negative half field cycles due to the asymmetric I-c(B,theta) characteristics of the conductor. Numerical simulations revealed a clear correlation between the magnetization loss and the asymmetric I-c(B,theta) data for the whole 360 degrees field-angle range in the REBCO conductor. The asymmetry in the I-c(B,theta) data about the ab-peak causes differences in magnetization loss values for the mirror-symmetric field angles. The asymmetry in the I-c(B,theta) data upon field reversal also results in differences between magnetization loss values for the positive and negative cycles. Published under an exclusive license by AIP Publishing.

Automated summary

Commercial high-T-c superconducting coated conductors exhibit asymmetric I-c(B,theta) characteristics under different magnetic field angles and temperatures, with simulation results reproducing the trend of experimental results. The asymmetric I-c(B,theta) characteristics of the conductor result in differences in magnetization loss values for positive and negative half field cycles.