Experimental Study on AC Loss of a Quasi-Isotropic Strand Fabricated by Coated Conductors in AC Magnetic Fields

AC loss of the superconducting conductor is one of the important factors for the application of the superconducting power devices since it determines the stability and operation cost. In this paper, based on introducing the structure of a quasi-isotropic high-temperature-superconducting (HTS) strand, we calculate ac loss of the quasi-isotropic HTS strand consisting of symmetrically stacked coated conductors using the Comsol Multiphysics software and present a calorimetric method for measuring ac loss of the HTS strand by optical fiber Bragg grating (FBG) in liquid nitrogen (LN2) temperature. Before the ac loss experiment, we calibrate the FBG in the temperature range of LN2 , which illustrates the rationality of the FBG measurement at LN2 temperature. ac loss can be obtained by the calibration between energy loss of the HTS strand against wavelength of the FBG. The experimental results are in accord with the calculations, which indicates that methods of the numerical calculation and the measurement are feasible, they can be principally extended to the ac loss computation and experiment of other HTS conductors with complex structure.