Superconducting cable joint resistance

Results of a parametric study of the 4.2-K resistance of lap joints between two 27-strand cables of multifilamentary Nb/sub 3/Sn wire are reported. All joints were between ribbon terminations made by rolling copper-encapsulated cable ends flat. Resistances as functions of current were inferred from current decay time constants of cable-in-conduit conductor loops connected by the joints. The resistances of 23 samples were measured (range of 0.2 to 3 n Omega ). It was found that lap joint resistance was a function of current. The influences of solder versus no solder, solder thickness, indium versus tin-lead, ribbon surface oxidation, solder flux, cable twist pitch, wire chrome plating, clamping pressure during heat treatment, ribbon aspect ratio, and joint length are reported.