Uniaxial Strain Induced Critical Current Degradation of Ag-Sheathed Bi-2212 Round Wire

The critical current degradation of Bi-2212 Ag-sheathed round wire subjected to uniaxial strain was studied at 4.2 K in 14 T background field. The strains applied on the sample are both tension and compression. The additional tensile strain caused by the difference in thermal expansion between the Bi-2212 round wire and Ti-6Al-4V alloy spring was calculated. The results showed that a drastic degradation of the critical current occurred when the intrinsic strain exceeded around 0.5% in tensile direction. For the compressive strain, the degradation of critical current was almost linear but more gradual than tensile strain. The intention is to use these results as a basis for Bi-2212 conductor and superconducting coil design.