Effects of contact resistance between strands with Cr/non-Cr coating in cable-in-conduit conductors

We have fabricated an experimental equipment which mechanically applies a force to stacked strands with two kinds (0 and 60 degrees) of crossing angles. We measured the contact resistance between the strands, the contact force applied to the strands and the deformation of the strands at three temperatures (293 K, 77 K and 4.2 K). We investigated two kinds of strands (bare surface and with Cr plate). From the experimental results, in the case of a line contact (when the intersection angle´s 0 degree) at liquid helium temperature, the ranges of the surface resistance of the Cr plated strands were between 4.3 × 10^-8 and 1.7 × 10^-7 Ωm², while the resistance of the bare strands were between 9.2 × 10^-9 and 2.7 × 10^-8 Ωm². Hence, effects of the Cr coating on the surface of the strands were clearly observed. The difference of the surface resistance appears to slightly depend on the intersection angles of the contact strands. The obtained results become fundamental data to simulate an electric circuit model of multi-stranded conductors and to estimate inter-strand coupling losses in the conductors.