AC losses in Nb/sub 3/Sn Rutherford cables with a stainless steel core

Electric measurements of coupling losses in five-layer stacks of Nb/sub 3/Sn Rutherford cables with a stainless steel (SS) core are made with the applied transverse 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 FO inter-strand coupling loss due to the existence of the resistive core is clearly observed. The measured loss for the latter (edge on, EO) field case is very small, that is, about 1/5000 times as large as the reduced loss. In order to explain these loss properties, two dimensional FEM analysis is carried out taking into account the details of the cable cross-section. The theoretical results show that the FO inter-strand coupling loss in the SS-cored 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 negligible EO loss corresponds to the intra-strand coupling loss produced in isolated strands due to high surface-resistance of the side-by-side contact.