Critical currents versus applied strain for industrial Y-123 coated conductors at various temperatures and magnetic fields up to 19 T

The strain dependence of the critical current in Y-123 tapes has been studied as a function of field and temperature up to strain values of 0.81%. For the particular tape configuration with a Ni–W substrate, the critical current was found to be reversible up to 0.51%. The I c (ε) curves have been measured at 4.2, 50 and 77 K at fields up to 19 T. In the reversible region, the decrease of I c (ε)/ I c (ε = 0) with ε was found to be more pronounced at higher fields and temperatures: at 17 T the decrease of I c / I co at ε irr was of the order of 9% and 25% at 4.2 and 50 K, respectively. At 77 K and 6 T, the corresponding decrease was 12%. Using the Walters spiral for tapes up to 0.80 m length, the V –I curves have been measured over three decades. At low electric field (0.01 µV cm −1 ) the n value is constant up to 0.81% strain, while at higher electric field it decreases with the applied strain.