Development of Bi-2212 conductors for magnet applications

Bi-2212/Ag superconducting composites are quite promising materials for expanding superconducting magnet applications to higher fields and temperatures than those allowed by present LTS systems. Three types of BSCCO-2212 conductor for magnet applications are under development at Oxford Superconducting Technology (OST). Prototype size batches of multifilament tape have recently been fabricated for use in a 5 T high field insert demonstration in collaboration with the National High Magnetic Field Laboratory. This insert achieved a world record setting 25 T central field in a superconducting magnet at 4.2 K. Substantial progress with multifilament wire continues, with the achievement of high field current densities (J(c)) that are considerably higher than those in the multifilament tapes. Optimization of dip-coated 2212 tape for MRI magnet applications is also underway, as part of a Superconductivity Partnership Initiative project. However, improvement of transport properties in long length conductors is necessary for commercial magnet applications. Recently, significant improvements in the engineering current density (J(E)) and J(c) performance have been achieved by optimizing the starting powders, the ceramic size and shape, the deformation processes, and the melt-solidification and post-annealing process parameters. In this paper the progress achieved with these conductors will be reported.