Numerical Calculation of Ac Losses in Stacked Bi-2223 Tapes Exposed to Oblique Magnetic Field

Abstract

We numerically calculated ac losses in a parallel conductor composed of three Bi-2223 tapes exposed to an external transverse magnetic field by means of a previously proposed two-dimensional finite element method that directly analyses the magnetic field distribution around the conductor. In this analysis, we can set a transport current in each Bi-2223 tape individually. Assuming no transport current in each tape, we estimated the ac losses in the parallel conductor with perfect transposition. We also calculated the ac losses in the parallel conductor without transposition under the condition that the total transport current is zero. It was found in the parallel field configuration that the ac losses are drastically decreased due to the transposition in a range of higher amplitude. In the case of perpendicular field, on the other hand, the ac losses are scarcely dependent on the transposition. Furthermore we numerically estimated the dependence of the ac loss on the field angle to the flat surface of the tapes in the transposed parallel conductor. The obtained results well explain the experimental ones especially in the higher amplitude of applied field.