Analysis of AC loss characteristics of high temperature superconducting coil

This paper reports an analytical study on AC loss characteristics of a high temperature superconducting coil wound with a Bi2223/Ag tape. The electromagnetic AC loss in the high temperature superconducting coil made by stacking pancake coils wound with the Bi2223/Ag tape was numerically calculated by using the measured DC data of the HTS tape. The calculated AC loss was compared with measured AC losses in Bi2223 HTS coils obtained in a previous study. It had been found that the measured AC losses in the coils contained large mechanical loss. For the comparison of the measured and calculated losses, the mechanical loss was subtracted from the measured total loss data to estimate the electromagnetic loss. The calculated AC losses were compared with the measured electromagnetic losses in the coils, producing rather good agreement. A possible way to reduce the AC loss in the HTS coil was also presented and discussed.