Measurement and Numerical Calculation of AC Losses in Second-Generation High Temperature Superconductor Current Leads

In order to study the effects of the structures of HTS current leads on AC losses, two different structure HTS current leads were fabricated. Based on the Clem model, the effects of external magnetic field on AC losses were taken into account. The coordinate system on the cross section of the current leads was established. By taking the advantage of coordinate translation and coordinate rotation, the distributions of the magnetic field in HTS current leads were obtained. On the basis, AC loss calculation models for the two different structure HTS current leads, rectangular skeleton current lead (RSCL) and dodecagon skeleton current lead (DSCL) were built. Then, calculation programs were compiled using MATLAB and AC losses of the two different structure HTS current leads were calculated. Finally, the experiments of AC losses of HTS current leads were carried out by an electrical method in liquid nitrogen environment. AC losses of the two different structure current leads were measured at different currents and different frequencies. The theoretical results and measured data were compared and the effects of the structures of HTS current leads on AC losses were analyzed. The calculation results of AC losses show the coordinate transformation model is more accurate than the Norris model. The results also show AC loss of DSCL is smaller than that of RSCL.