CEBAF cryogenic system

The CEBAF cryogenic system consists of three refrigeration systems: Cryogenic Test Facility (CTF), Central Helium Liquefier (CHL) and End Station Refrigerator. We now have 49,000 hours of CTF and 35,000 hours of CHL operation. The CHL is the main cryogenic system for CEBAF, consisting of a 4.8 kW, 2.0 K refrigerator and transfer line system to supply 2.0 K and 12 kW of 50 K shield refrigeration for the linac cavity cryostats and 10 g/sec of liquid for the End Stations. We describe the nine year effort to commission these systems concentrating on the CHL with its high tech component-the cold compressors.