Cryogenics for the Rare Isotope Accelerator project

With 600 meters of superconducting accelerator, the Rare Isotope Accelerator (RIA) facility will have an extensive cryogenic system operating at both 2.0 K and 4.4 K. Approximately 250 4.4 K resonators, 200 2.0 K resonators, 160 4.4 K magnets, and several 4.4 K bunchers will be used in a 1.4-GV superconducting CW driver linac. Ion beams ranging from protons (up to 900 MeV) to uranium (up to 400 MeV per nucleon) at beam powers up to 400 kW will be produced. The facility will also have a superconducting linac to accelerate short-lived rare isotopes produced by the driver. This post accelerator is composed of another 100 superconducting resonators and associated superconducting focusing magnets. Liquid helium will also be provided to a variety of experimental instruments including, for example, large superconducting magnetic spectrographs. Overall, the liquid helium refrigerator will need to provide approximately 8.6 kW of cooling at 2.0 K, 4.8 kW at 4.4 K, and 15.3 kW at 35 K for shield cooling. A review of the various loads, cryostats, distribution system, and refrigeration schemes will be presented along with some special needs for reliable operation