Fabrication and Test of an 8-T Superconducting Split Magnet System With Large Crossing Warm Bore

A conduction-cooled superconducting split magnet system with large crossing warm bore has been successfully constructed in our laboratory for material processing applications. The magnet system design was described in a previous paper. The magnet is composed of six NbTi low temperature superconducting coils, which generate 5.5-T central magnetic field and two Bi2223/Ag high temperature superconducting (HTS) insert coils, which generate 2.5-T central magnetic field and assembled in the form of split coil groups. The magnet has a 136-mm split gap to accommodate the crossing warm bore of 100 mm in diameter. The magnet system is cooled by two GM cryocoolers. The initial cooldown takes 9.2 days and the final temperature of the magnet is about 4.0 K. The HTS coils and NbTi coils are to be operated in the driven mode with two independent power supplies, under the operating currents of 200 A (HTS) and 139 A (NbTi), respectively. The magnet is successfully powered up to 8 T with a the ramp time of 290 min. In this paper, the fabrication and test of the superconducting split magnet system are presented.