Electromagnetic and calorimetric measurements for AC losses of a YBa ₂Cu₃O_7-δ coated conductor with Ni-alloy substrate

The AC losses of a rolling-assisted-biaxially-textured-substrate (RABiTS™) processed YBa₂Cu₃O_7-δ (YBCO) coated conductor(Goyal et al 1996 Appl. Supercond.4 403-27) with Ni-alloy substrate and Cu stabilizer were measured at 77K by both calorimetric (CM) and electromagnetic (EM) methods. In the CM method, improvements in the measurement were observed when a Cernox temperature sensor was used to measure the temperature rise on the sample instead of a differential thermocouple. The effect of heat transferred from current leads was taken into account to improve the accuracy of the CM results. In the EM method, the magnetization losses of the sample in a perpendicular applied field were measured by an in-plane pick-up coil. The calculation of the calibration factor C of the pick-up coil is discussed. Good agreement between AC loss results obtained from the CM and EM methods confirmed the validity of our measurements and calculations.