Abstract
The LHC project is in progress at CERN. The LHC accelerator, whose beam energy is 7TeV, consists of more than 2, 000main superconducting magnets. Almost all the magnets are to be operated at 1.9K pressurized He II cooling because of the high magnetic field. The cooling system consists of 8 refrigerator units with a large equivalent capacity of 18kW at 4.5K. Each unit covers to cool the aligned magnets along a distance of 3.3km long. In order to obtain 1.9K pressurized He II with better efficiency, 8 cold compressor units will be installed into the 8 refrigeration systems. The necessary cooling of the magnets is obtained with pipe-shaped heat exchangers embedded in magnet iron yokes. The minimum cooling unit of the magnets is composed with the 6main dipole and 2main quadrupole magnets. The unit length is 106m. This paper will describe the outline of the He II refrigeration system.
