Tensile Strain/Transverse Compressive Stress Dependence of Critical Current in Ag Sheathed Bi (2212) 7-Core Superconducting Wires

Abstract

The mechanical properties and the axial tensile strain/transverse compressive stress dependence of the critical current, I_c, in Ag sheathed Bi (2212) 7-core superconducting wires with different construction were evaluated at a temperature of 4.2K and a magnetic field of 14T. Increase of the superconductor volume fraction shifted the stress-strain curves upward. The tensile strain for I_c degradation onset was in the range of 0.14-0.27%. It depended on the residual compressive strain and the thickness of the superconductor layer. On the other hand, the transverse compressive stress for I_c degradation onset was in the range of 9-20MPa. The wires with thin Ag sheath layer showed a remarkably large degradation in the onset stress. There was no correlation between the onset stress for degradation of I_c caused by the tensile stress and that caused by the transverse compressive stress.