AC losses in a type II superconductor strip with inhomogeneous critical currentdistribution

Abstract

Analytical formulae derived by Brandt and Indenbom (1993 Phys. Rev. B 48 12893–906) andNorris (1970 J. Phys. D: Appl. Phys. 3 489–507) are often used to calculate themagnetization and AC transport current losses in HTS strip conductors, respectively. Inthese formulae, homogeneous distribution of critical sheet current densityσc in the strip is assumed. However, it is considered thatσc distributions are inhomogeneous in actual HTS strips and that the inhomogeneousσc distributions cause deviations of the measured AC loss data of actual HTS strips from thoseformulae. A semi-analytical method to calculate AC transport current and magnetizationlosses is derived for a type II superconductor strip with inhomogeneous distribution ofσc in the direction of the strip width. The method is derived modifying the analysis ofBrandt et al. The validity of the semi-analytical method is shown by comparingthe results calculated by this method with those calculated by the Norris andBrandt formulae and by a different method of our previous work and also withexperimental data. Moreover, it is shown that the deviation of the measureddata from the Norris and Brandt models can be estimated by assuming properσc distributions.