Effect of Barrel Material on Critical Current Measurements of High-${rm J}_{rm c}$ RRP ${rm Nb}_{3}{rm Sn}$ Wires

摘要

${rm Nb}_{3}{rm Sn}$ strands extracted from a 20-strand rectangular Rutherford cable were reacted on either stainless steel or Ti-alloy barrels and the critical current, ${rm I}_{rm c}$ , in the field range of 8–11.5 T was measured on ITER-type barrels made from Ti-6Al-4V alloy, 304 stainless steel and G-10. Measurements on the “standard” Ti-alloy barrel using the test procedure employed at BNL are shown to reproduce ${rm I}_{rm c}$ for extracted strands to $pm$2%. The ${rm I}_{rm c}$ data for the sample mounted on the “standard” Ti-alloy are fit to the deviatoric strain scaling model developed for ${rm Nb}_{3}{rm Sn}$ by the University of Twente group using an arbitrary pre-strain. Using the parameters for this fit, the ${rm I}_{rm c}$ data for the other barrels are fitted by only adjusting the strain. Using this procedure, the strain difference due to the barrel material is determined. Assuming a thermal pre-strain of $-$0.2% for the sample measured on the Ti-alloy barrel, the use of stainless steel barrel increases the compressive strain by $-$0.07%, that of G-10 by $-$0.10%. With the wire soldered to the stainless steel barrel, the strain increases to $-$0.15%. Details of this study are prese nted.