React-wind-and-sinter technique for Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub 8/ high T/sub c/ coils

The fabrication of HTS coils and magnets with critical current densities close to short samples is an important challenge in high field magnet research and development. While wind-and-react suffers from inaccurate temperature control, react-and-wind technique generates strain inside the core during winding. A new technique is being developed at the NHMFL: the react-wind-and-sinter technique. Long lengths of powder-in-tube conductor are reacted uniformly by pulling the tape continuously through a temperature profile in a controlled atmosphere furnace. The precursor is partial-melted and cooled to form large grains. The tape is then wound into the desired coil shape and sintered at constant temperature to repair cracks that developed during winding and achieve high phase purity and grain alignment.