Application of JLab 12GeV helium refrigeration system for the FRIB accelerator at MSU

Abstract

Abstract. The planned approach to have a turnkey helium refrigeration system for the MSU-FRIB accelerator system, encompassing the design, fabrication, installation and commissioning of the 4.5-K refrigerator cold box(es), cold compression system, warm compression system, gas management, oil removal and utility/ancillary systems, was found to be cost prohibitive. Following JLab's suggestion, MSU-FRIB accelerator management made a formal request to evaluate the applicability of the recently designed 12GeV JLab cryogenic system for this application. The following paper will outline the findings and the planned approach for the FRIB helium refrigeration system.

Testing and analysis of stand-by operating modes for FRIB helium refrigeration system

“…Mode 3 indicated an increase in cold box supply (HP) pressure but overall reduction in supply flow. The FRIB 4.5 K refrigerator is designed for a liquefaction dominated load [5,8,9], where major share of the thermal load exergy is the cold compressor flow, which can be up to 180 g/s, supplied at 4.5 and returned at 30 K. The turbo-expander nozzle flow coefficients are selected based on this load. For an isothermal refrigeration dominated load (as is the case in these tests), the T3-T4 turbo-expander string recycles more flow than is optimal, due to the fixed flow coefficient of the turbo-expander nozzles, resulting in a colder operating range.…”

FRIB cryogenic distribution system

“…The considerations for this design included the various modes to operate both 4.5 K and 2 K components in the cryomodule, valves required for process control, and independent cool down and warm up of the magnets for degaussing. Bayonet type interfaces between the transfer line and the cryomodule have been incorporated into the design [2].…”

“…It has been recognized that additional refrigeration capacity will be required to add bayonets to the distribution system, but the improved availability and commissioning capabilities outweigh the importance of the increased heat load. More information about the FRIB refrigeration system and heat loads can be found in another publication from the current conference proceedings [2].…”