The inter-strand contact resistance of Nb3Sn cable-in-conduit conductor with hydrocarbon oil

摘要

The inter-strand contact resistance (R-C) of Nb3Sn cable-in-conduit conductors (CICCs) is a very important parameter which strongly correlates with ac losses and current redistribution behavior of the CICCs. One way to obtain the desired R-C is to apply a layer of hydrocarbon oil on the Nb3Sn strands before the CICC Nb3Sn reaction heat treatment. In this paper, we measured R-C for a Nb3Sn CICC sample fabricated with hydrocarbon oil. The measurements were performed using an apparatus designed to apply transverse load and load cycling on CICCs at 4.2 K. Resistances R-C between strands of different cabling stages were measured with transverse load up to 188 kN m(-1) and load cycles up to 10 000. The results show that R-C of the sample increases almost linearly with the first loading. With load cycling, R-C increases rapidly at first, but becomes saturated after similar to 100 cycles. After 10 000 load cycles, R-C decreases with increasing load at a decreasing rate. These behaviors are comparable to observations for CICC with Cr plated strands reported in the literature. Therefore from the R-C point of view, Nb3Sn CICCs with hydrocarbon oil on strands may be used as a low cost alternative to CICCs with Cr plated strands.