The Development of High Field Magnets Utilizing Bi-2212 Wind u00026; React Insert Coils

摘要

Wind u00026; react Bi-2212 inserts have been manufactured and tested inside a wide-bore ${rm NbTi}-{rm Nb}_{3}{rm Sn}$ magnet providing a background field up to 20 T at 4.2 K. A pair of six-layer concentric coils both achieved critical currents of 350 A $(J_{E}=200 {rm A/mm}^{2})$ in a 20 T background field. A thicker 14-layer insert made from 119 m of round wire had a critical quench current ${rm I}_{rm Q}$ of 287 A $(J_{E}=162 {rm A/mm}^{2})$ at the same field and contributed to a combined central field of 22.5 T. This is a record for a fully superconducting magnet at 4.2 K. The 14-layer coil, equipped with an external protective shunt, was used for an extensive series of quench measurements and endured > 150 quenches without damage. Minimum quench energies were found to be in the range of 200–500 mJ in background fields of 15–20 T when the coil carried 70–95% of its critical quench current.