Wire and tape fabrication for DC and AC applications

Superconducting tapes are produced by the powder in tube method, using silver tubes packed with the ceramic powder precursor. After drawing the tube to mm size wire, cold rolling is used to produce tapes typically 3-5 mm wide and 0.1-0.3 mm thick. Alternatively, a coating of the precursor is deposited on a flat silver ribbon. This is followed by a thermal treatment to form the required superconducting phase and to sinter the grains to provide a continuous superconducting path along the tape. Due to the anisotropy of the HTSC materials, their critical current density J_c depends on the angle between the transport current and the layered structure of the ceramic crystal. Also, the effect of an external magnetic field on J_c varies with the angle between the field and the plane of the tape