A pressurized He II cryogenic system for the superconducting magnet test facility at KEK.

A cryogenic system for the test facility of high gradient superconducting quadrupole magnets for Large Hadron Collider (LHC) at CERN has been constructed at KEK. It consists of a vertical double-bath cryostat in He II at an atmospheric pressure, a vacuum pumping system and a pair of refrigerator/liquefiers to maximize the cooling capacity to test 6.3m long magnets. The system has been successfully operated in the first cold test at the 6.3m prototype magnet since March 2001 with a refrigeration power of 55.5W at 1.9K. The design and test results are described in this paper. [ABSTRACT FROM AUTHOR]