AC losses in Nb3Sn Rutherford cables with a stainless steel core

Electric measurements of coupling losses in five-layer stacks of Nb3Sn Ruth erford cables with a stainless steel (SS) core are made with the applied tr ansverse magnetic-field both normal and parallel to the plane of the cable. For the former (face-on, FO) field case, a one-order reduction of the PO i nter strand coupling loss due to the existence of the resistive core is cle arly observed. The measured toss for the latter (edge-on, EO) field case is very small, that is, about 1/5000 times as large as the reduced loss. In o rder to explain these loss properties, two dimensional FEM analysis is carr ied out taking into account the details of the cable cross-section. The the oretical results show that the FO inter-strand coupling toss in the SS-core d cable is determined mainly by the thickness and conductivity of not only the SS core but also of the outermost bronze region, and that the negligibl e EO loss corresponds to the intra-strand coupling loss produced in isolate d strands due to high surface-resistance of the side-by-side contact.