Production of NbTi CICC´s for SST-1 project at IPR

A total of 24 pieces of NbTi CICC with outer dimension of 14.8 mm×14.8 mm and a piece length of 600 m each have been successfully fabricated for building TF and PF coils. The CICC is made through the roll forming and welding process. The insert cable with a scheme of 3×3×3×5 is made from 0.86 mm diameter multifilamentary NbTi/Cu strand with 10 μm diameter NbTi filaments embedded in Cu matrix at a Cu ratio of 4.9. No treatment is applied to the strand surface. A 0.025 mm thick SS304 tape is wrapped on the finished fourth stage cable. A 15 mm thick SS304L strip is then roll formed around the wrapped fourth stage cable and TIG welding 6 applied continuously at the top longitudinal seam. The welded conduit is finished to the final square dimension, by passing it through sizing rolls and turks head rolls set at the end of the jacketing line. The critical current for a CICC, estimated through multiplying an average I_c (without self-field correction) for the 10 extracted strands by the number of strands of 135 in a CICC, is approximately 38 kA at 5 T, 4.2 K. This means that there is: no significant degradation of I_c´s for the strands due to the cabling and jacketing process. It is confirmed that the finished CICC pieces of 600 m each show a He leakage level well below 0.2×10^-3 Toll 1/s