Summary and results of the cryoplant operation for HERA

For about 15 years, leptons and protons collided inside the HERA particle accelerator with the intension of investigating the protons’ inner structure. 646 superconductive electromagnets and 16 superconductive cavities had to be constantly surrounded by liquid helium to operate at a temperature of around 4 K. To ensure the helium supply of HERA’s superconductive components a highly productive refrigeration plant was built. In this paper we report on the experience gathered during nearly 20 years of operation of the refrigeration plants’ 3 cold boxes and the corresponding 14 screw compressors together with the helium distribution system and the purification system.