Progress in<tex>$rm Bi$</tex>-2212 Wires for High Magnetic Field Applications

Abstract

The high field critical current density (J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> ) and engineering current density (J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</sub> ) in multifilament Bi-2212 round wires continue to improve, suggesting this material may well enable the next generation of high field magnets. The critical current in round wires shows no anisotropy with respect to applied field. Recent efforts have focused on characterizing the anisotropy in low aspect ratio rectangular wires; these results show that isotropic 2212 wire should be possible with rectangular cross sections if the aspect ratio is kept below 1.6. A braided insulation is now available for these conductors, enabling a robust procedure for wind-and-react coils. I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> and generated field have been measured in a series of such coils of increasing dimensions. Performance of two of these coils has been measured in background fields up to 19 T, showing good prospects for high field magnet application of this conductor