Development of a 3 T-10” Bore MgB2 Magnet at GE

MgB2 may be the future superconducting wire material for industrial magnets due to its higher operation temperature and potentially lower cost. Application of pre-reacted MgB2 wire to a medium scale magnet has been started at GE with NIH support. Several test coils made with wet winding processes showed unexpected remnant voltage, even though the pre-reacted wire's short sample tests had passed the criteria of 1 μV/cm. Investigations revealed that the wire's non-uniformity and defects over the long length were the root cause of the remnant voltage. A coil with refined wire of good lengthwise uniformity showed no remnant voltage.Along with the coil development, superconducting joints between two MgB2 pre-reacted multi-filamentary wires have been tried. The joints so far have showed up to half of the designed Ic.The magnet will be cooled by a cryo-cooler through closed loop cooling circuits containing either helium or hydrogen.