Angular Dependence of Critical Current in Ag-Seathed Bi(2223)Superconductor Tape

The critical current I_c (B.T.θ) of Ag-sheathed Bi (2223) tape was measured at 4.2 and 77k in magnetic field up to 6T as a function of the field direction. The maximum I_c is observed when the flux line are along the CuO₂ planes. This effect is due to an intrinsic pinning between CuO₂ layers. When H > 0.5T at 4.2K, I_c decreases very slowly with the magnetic field. The results are consistent with our early-proposed scaling laws for flux pinning in Ag-sheathed tape.