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

Nb
₃
Sn strands extracted from a 20-strand rectangular Rutherford cable were reacted on either stainless steel or Ti-alloy barrels and the critical current, I
_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 I
_c
for extracted strands to ±2%. The I
_c
data for the sample mounted on the “standard” Ti-alloy are fit to the deviatoric strain scaling model developed for Nb
₃
Sn by the University of Twente group using an arbitrary pre-strain. Using the parameters for this fit, the I
_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 presented.