Transport and magnetization properties of rolled RRP Nb3Sn strands

Restack Rod Process (RRP) strands with 54 and 108 sub-elements were rolled from 0.7 mm diameter to 0.45 mm thickness to simulate the deformation of strands at the edges of Rutherford cables. Various diagnoses were then applied to assess performance and stability. Transport measurements were used to assess the effect of rolling on the critical current. Magnetization measurements were used to probe superconducting pathway bridging between deformed sub-elements. The copper residual resistivity ratio RRR was also measured to assess tin contamination due to thinned or ruptured diffusion barriers. While systematic changes were observed in all three measurements with increasing deformation, RRR showed the strongest changes. The implications of these measurements for cable stability, and their relationship to observations of the strand cross section by light microscopy, are discussed.