Filament decoupling and magnetization loss of multifilamentary Bi2223 superconducting tapes

Several types of multifilamentary Bi2223 superconducting tape were fabricat ed to study the filament decoupling and its effect on the magnetization los s reduction. First, twisted and untwisted multifilamentary Bi2223 tapes wit h pure silver matrix were prepared. The spacing between filaments,vas incre ased to ensure the suppression of the interfilament bridging. Therefore, th e engineering current density decreased, while the critical current density was kept at 150 A/mm(2). Measured magnetization loss of the tapes indicate s" that filaments are decoupled by twist in the parallel magnetic field, an d the hysteresis loss is reduced. Second, the interfilament resistive barri ers were introduced. Several materials were tested as the barrier material to study their compatibility with the formation of Bi2223 phase during the fabrication process. The tapes with resistive barrier were fabricated succe ssfully with a couple of meters of piece-length. DC magnetization of the fa bricated tapes was measured by a SQUID magnetometer. The magnetization - te mperature curves indicate that Bi2201, notsuperconducting at 77 K, and the Altos do not affect the formation of Bi2223 superconducting phase. The tran sverse resistivity of a Bi2201-barrier tape, estimated from the measured co upling time constant, is 4.7x10(-8) am. Results of AC magnetization loss me asurement indicate that the filaments can be decoupled by the Bi2201 barrie r.