Control of the Tevatron Satellite Refrigeration System

The six kilometer ring of superconducting magnets which forms the Fermilab Tevatron is cooled by a Central Helium Liquifier (CHL) which provides liquid helium (and nitrogen) to 24 satellite refrigerators distributed around the ring.1 The system is controlled by 31 independent microprocessors operating over 400 servo loops. The central computer system provides monitoring, alarms, logging and changing of parameters.