Instantaneous AC Loss and Inductance Measurement of HTS Coil With Finite-Data-Window Least Squares

AC loss is a critical concern for the stability of superconducting device. Various experimental methods are available for measuring AC loss in superconductors, with electrical measurement techniques being widely adopted. However, these methods only measure average loss and often disregard variations in superconductor inductance with current, which may lead to inaccuracy. This study introduces a finite-data-window least squares method to measure instantaneous AC loss in coils wound with YBCO tapes. By comparing the results with those obtained through the integral method, it is demonstrated that the proposed approach effectively measures instantaneous AC loss for coils with limited turns. Furthermore, the pattern of superconducting coil inductance in relation to current variations is examined.