Low temperature high magnetic field activities at the Francis Bitter National Magnet Laboratory

The high field facilities of the FBNML offer to its 300 or more annual users a wide range of cryogenics support to complement its 28 water-cooled magnets and two hybrid magnets. That support includes 9 metal cryostats, three 3He refrigerators, three dilution refrigerators, and a liquid H2 apparatus for high current Jc tests in the 14–20 K range. Recently, the Laboratory’s newest hybrid magnet achieved a record dc field of 34.2 tesla in a 33-mm bore. Its Bitter magnet contributed a field of 21.7 T; the surrounding superconducting magnet, operating at 1.7 K, produced 12.5 T. Subsequently, a field of 37.25 ± 0.5% T was measured in a 2-rnm gap between Ho pole pieces immersed in a 4.2 K bath. The facility’s original hybrid magnet routinely operates at 30 T and has logged more than 3000 hours since 1981.