Local extreme values in critical current of anisotropic Bi-2223/Ag tapes

Abstract In this paper, the applicability of a Kim’s model based approximation for the critical current, I c ––magnetic flux density, B , dependence of anisotropic HTS tapes is examined. It has been suggested that the external axial magnetic field can even increase the performance of the solenoidal HTS coil. Therefore, the model was applied to a Bi-2223/Ag sample in order to study the variation of I c with the magnetic flux component, B x oriented in parallel with the broad tape face. The normal component B y is kept constant. According to the computations at temperatures below 50 K, I c had both local minimum and maximum with respect to B x when B y was within a certain temperature dependent interval. When B y was further increased I c ( B x ) had a global maximum at non-zero B x . Direct interpolation with measured data confirmed this behaviour. A new type of measurement is suggested in order to check these local extremes accurately without any interpolation errors.