Significant reduction in AC transport self-field losses of Ag-sheathed Bi2223 tapes achievedby changing filament arrangements

Abstract

Significant reduction in AC transport self-field losses has beenachieved at 77 K for Ag-sheathed Bi2223 multifilamentary tapes withm × n (m,n = 3 or 5) filament arrangements, fabricated via a rectangular deformation process usingtwo-axis rollers. This achievement is not effected by introducing resistive barriers but bychanging filament arrangements. Despite the main contribution being the hysteresis loss ofthe superconductor, the loss values are decreased by approximately 50–70%, compared withthe values for multifilamentary tapes obtained by a standard powder-in-tube process.More complicated filament arrangements achieved via a rectangular deformationprocess lead to further reduction in the loss values. On the basis of numericalcalculations, the loss reduction is mainly ascribed to a division of the field-freecore in the filament groups near the tape edge under AC current transmission.The study should pave the way to removing an obstacle to loss reduction andto developing tape strands with low loss values satisfying practical demands.