Theoretical evaluation of perpendicular-field losses in stacked high-Tc superconducting tapes

AC losses of bundles of non-twisted superconducting tapes in an external magnetic field perpendicular to the wide faces of them are evaluated by means of both numerical simulation and theoretical consideration. First, the AC losses are numerically calculated in a slab, whose thickness is equal to the width of filamentary region in the tape. Next, in order to add the effects of magnetic interaction between tapes, the effective demagnetization factors of stacked tapes are estimated with a theoretical expression, in which it is assumed that the filamentary region is regarded as a uniform magnetic material in the form of an elliptic cylinder. By combining the AC loss properties of slab and the effective demagnetization factors of stacked tapes, it is finally found that the experimental results can be well reproduced in three kinds of Bi-2223 multifilamentary tapes.