The $I_{C}$ Irreversible Strain of Some ITER High $J_{C}$

ITER high J _C Nb₃Sn wires are designed to compensate for the performance degradation due to transverse electromagnetic force in cable-in-conduit-conductor. J _C characterization of these wires, especially as a function of axial strain, is very important. We performed I _C irreversibility strain epsiv_irr-epsiv_max measurements and geometry examinations on two types of ITER high J _C Nb₃Sn wires. epsiv_irr-epsiv_max is measured in a 18 T magnetic field by a straight pull device developed at the NHMFL. Consistent difference in epsiv_irr between the two types of strands is observed. We found that the epsiv_irr-epsiv_max is ~ 0.3% for the type of strands with higher J _C and ~ 0.4% for that with lower J _C . This can be correlated to the difference in their geometry.