Residual Resistance Ratio in $\hbox {Nb}_{3}\hbox {Sn}$ Strands During ITER TF Conductor Manufacture and After SULTAN Tests

The residual resistance ratio (RRR) is an important parameter affecting the stability of superconductors and the quench protection properties of magnets. During the manufacture of cable-in-conduit-conductors based on Nb₃Sn strands, RRR may change noticeably. We studied the RRR of strands in as-received condition and at different stages of the TF conductor manufacturing (cleaning and Cr-plating of strands, cabling and final compaction). The RRR of strands extracted from a TF conductor sample after electromagnetic and thermal cycling at the SULTAN test facility has been studied also. For this purpose after testing at SULTAN the strand samples were extracted from different locations in the cross-section of the TF conductor and from different positions along the axis. The results about the RRR variation during the conductor manufacturing process and after SULTAN tests are presented and discussed.