Small reversible axial-strain window for the critical current of a high performance Nb3Sn superconducting strand

The engineering critical current density (J(C)) of a Nb3Sn restacked-rod-process superconducting strand is reported as a function of magnetic field (B <= 28 T), applied axial strain (-0.9%<=epsilon(A)<= 0.2%), and temperature (4.2 K <= T <= 14 K). Although the strain tolerance of J(C) is similar to other strands, the strain range over which J(C) is reversible is limited in both tension and compression. Samples were partially damaged when the intrinsic strain (epsilon(I)) was increased from -0.74% to -0.97% in compression and grossly damaged when epsilon(I) was only 0.13% in tension.