DEVELOPMENT OF TWISTED BI-2212 AND BI-2223 POWDER IN TUBE CONDUCTORS FOR AC APPLICATIONS

Within Alcatel Alsthom Group, Alcatel Cable and Alcatel Alsthom Recher che Center have undertaken a HTc research program, with support from E DF : the aim was to develop conductors suitable for ac applications, w here major market opportunities are expected, For ac applications at 5 0 Hz low ac loss conductors with a resistive matrix material and a twi st length of the superconducting filaments of less than 10 mm are requ ired. Bi-2223 and Bi-2212 conductors are fabricated up to lengths of 2 00 m of 64 filaments tape by the patented rectangular Alcatel Alsthom route, Recently Bi-2212 conductors for 20 K applications have been tes ted at liquid helium temperatures, Different Bi-2212 conductors with a twist length of 7 to 9 mm, with a silver-alloy matrix and a cross sec tion of 0,5 mm x 3 mm have been realised, In such conductors transport currents of 400-500 A have been measured at 4 K in self fields with a very good reproducibility, The engineering current density in the wir e has reached the threshold value of J(e) = 30'000 A/cm(2), The superc onducting volume fraction of the conductor is 18% which results in a c ritical current density in the superconductor of J(c) = 170'000 A/cm(2 ), At liquid nitrogen temperature transport currents of 18 A are carri ed in this conductor, For this temperature range the development of a Bi-2223 conductor is under progress, For instance, different untwisted conductors with transport currents up to I-c(77K) = 60 A and critical current densities up to are realised.