A 13 T-1.8 K NbTi laboratory test coil

The design and performance characteristics of a NbTi laboratory magnet and associated cryogenic system are discussed. The magnet is a hybrid-solenoid design consisting of an 11-T 10-cm bore NbTi coil and a 2-T 4-cm bore NbTi-NbTiTa insert. The two coils are installed in a pressurized He II bath, which maintains the temperature between 1.7 K and the liquification point temperature of 2.7 K at an applied pressure of 1 bar. The bath temperature is regulated by control of the vapor pressure above a low-pressure heat exchanger immersed in the He II region. As configured, the cryogenic system provides unattended temperature stability to within 2 mK. Under test, the magnet system performed well, achieving 13 T on the first charge.