Central refrigeration system for the superconducting HERA proton magnet ring

The refrigeration system for the superconducting HERA magnet ring is presently being installed at DESY. It consists of three refrigerators and three corresponding compressor groups as well as redundant compressors, oil and water removal systems, cryogenic purifiers, liquid helium dewars and 4000 m3 of room temperature helium storage capacity. The refrigeration plant which is located in a central refrigerator building and the helium distribution system around the 6336 m long ring tunnel of HERA to supply the superconducting magnets are described. The total capacity of the system is 20.3 kW refrigeration and 61.5 g/s current lead cooling gas rate at 4.3 K as well as 60 kW for the cooling of radiation shields between 40 K and 80 K. The operation of the system will be controlled and automated by a control computer system