Numerical analysis of AC loss in high T/sub c/ twisted tape carrying AC transport current in external AC magnetic field. Effect of twisting on loss reduction

The effect of twisting in BSCCO tapes on the loss reduction is discussed by a numerical analysis using the finite element method. The optimal twist pitch giving the lowest loss for the tape carrying the AC current under the AC magnetic field is presented. The numerical analysis takes the smooth E-j characteristics, the twisted structure and the dynamic resistivity into account, which allows more accurate loss estimations. For the BSCCO tape with a typical dimension of 3 mm/spl times/0.2 mm, the optimal twist pitch is around 10 mm, when it is carrying the AC transport current with normalized amplitude I/sub t//I/sub c/=0.8, under the parallel magnetic field to the tape face.