Fermilab central helium liquefier operations

This chapter discusses the use of liquid helium to cool the Fermilab superconducting accelerator. Liquid from the Central Helium Liquefier (CHL) is transported in a six kilometer circular transfer line and each satellite withdraws the amount required to boost its refrigeration capacity to the necessary level. Topics considered include the compressor, the heater, the control system, gas storage, liquid storage, the nitrogen reliquefier, gas purification, initial and early operation, and recent operation. The liquid helium is warmed to near ambient temperature in the satellite heat exchangers. The satellite compressors return the excess inventory to the CHL via a 20 bar gas header. This gas is injected into the high pressure supply to the cold box. Some turbine instabilities have been experienced, including the destruction of a turbine during the initial start-up