Interstrand Resistance Measurements on the Conductor Terminations of TFPRO2 and JATF3 SULTAN Samples

A number of ITER TF cable-in-conduit samples that have been tested in the SULTAN facility performed significantly below the single strand expectations. Although performance degradation related to transverse electromagnetic loads plays a role in ${\rm Nb}_{3}{\rm Sn}$ CICCs, a similar effect can occur when the current in the sample is non-uniformly distributed among the strands, driving part of the strands into saturation already at low currents and temperatures. A sufficiently homogeneous current distribution at low electric field level (less than 10 $\mu{\rm V/m}$) requires low interstrand resistances in the sample terminations and/or a homogeneous distribution of contact resistances between strands and the joint's copper sleeve.