Coupling losses in flat superconducting cables with considerable edge currents between the strands

Abstract

We calculate the ratio of the coupling losses and the current transfer factor for two structures compared with the simple Rutherford-type cable: additional conducting layer on the cable edges (A) and inclusion of a central layer with high resistivity (B). We then examine the possibility of designing cable structures with increased stability against electromagnetic perturbations. Whereas in case (A) both the coupling losses and the amount of the transferred current increase, it is just the opposite in case (B). However, for obtaining cable designs with higher stability, it seems to be inevitable to cut the well conducting edge sheath in segments whose lengths do not exceed the cabling or twist pitch. The crucial question for cables with such segmented edge layers in case (A) is then, whether the increased coupling loss density close to the edges is still tolerable from the cooling point of view. It is suggested, that the placing of conducting layer at the cable centre would lead to cables with much higher stability than placing it close to the cable edges.