The inter-strand contact resistance ofNb3Sn cable-in-conduit conductor with hydrocarbon oil

Abstract

The inter-strand contact resistance(RC)of Nb3Sn cable-in-conduit conductors (CICCs) is a very important parameter which strongly correlateswith ac losses and current redistribution behavior of the CICCs. One way to obtain the desiredRC is to apply a layer of hydrocarbon oil on theNb3Sn strands beforethe CICC Nb3Sn reaction heat treatment. In this paper, we measuredRC fora Nb3Sn CICC sample fabricated with hydrocarbon oil. The measurements were performed using anapparatus designed to apply transverse load and load cycling on CICCs at 4.2 K. ResistancesRC between strands of different cabling stages were measured with transverse load up to188 kN m−1 and load cycles up to 10 000. The results show thatRC of the sample increases almost linearly with the first loading. With load cycling,RC increases rapidly at first, but becomes saturated after∼100 cycles. After10 000 load cycles, RC decreases with increasing load at a decreasing rate. These behaviors are comparable toobservations for CICC with Cr plated strands reported in the literature. Therefore from theRC pointof view, Nb3Sn CICCs with hydrocarbon oil on strands may be used as a low cost alternative to CICCswith Cr plated strands.