Performance Assessment of Industrial Prototype Cryogenic Helium Compressors for the Large Hadron Collider

In order to develop the technology of large-capacity refrigeration at superfluid helium temperature, essential for the LHC project, CERN has procured from industry three prototype single-stage hydrody namic cryogenic helium compressors, based on different construction choices, and tested them in the laboratory. After recalling the common functional specification, as well as the main design features of the three machines, we present comparative performance results, and draw conclusions as concerns future full-scale machines for the LHC.