Angular, Temperature, and Strain Dependencies of the Critical Current of DI-BSCCO Tapes in High Magnetic Fields

High critical current density (Jc) DI-BSCCO Bi-2223 superconducting tape has been developed by Sumitomo Electric Industries (SEI) using the Controlled Over-Pressure (CT-OP) technique to improve the texturing and densification. Further enhancement of the mechanical properties has been obtained using lamination. We have investigated the effect of magnetic field and field orientation on Jc for a series of test DI-BSCCO tapes at 77 K and 4.2 K under tensile and compressive strains. These critical current data are strongly influenced by the anisotropy of Bi-2223, the texturing of the tape and its architecture. The magnetic field and angular dependence of Jc at 77 K can be described using a simple anisotropic exponential magnetic field model which includes the effects of the two-dimensionality and grain misalignment in these composites. The variation in the normalized J_c with respect to the strain is linear over the reversible range of strain where the gradient of the strain dependence is independent of temperature and field. The reversibility of J_c is extended further into the compressive regime after J_c degradation by compression.