Refrigeration Options for the Advanced Light Source Superbend Dipole Magnets
The 1.9 GeV Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL) produces photons with a critical energy of about 3.1 keV at each of its thirty-six 1.3 T gradient bending magnets. It is proposed that at three locations around the ring the conventional gradient bending magnets be replaced with superconducting bending magnets with a maximum field of 5.6 T. At the point where the photons are extracted, their critical energy will be about 12 keV. In the beam lines where the SuperBend superconducting magnets are installed, the X ray brightness at 20 keV will be increased over two orders of magnitude. This report describes three different refrigeration options for cooling the three SuperBend dipoles. The cooling options include: 1) liquid helium and liquid nitrogen cryogen cooling using stored liquids, 2) a central helium refrigerator (capacity 70 to 100 W) cooling all of the SuperBend magnets, 3) a Gifford McMahon (GM) cryocooler on each of the dipoles. This paper describes the technical and economic reasons for selecting a small GM cryocooler as the method for cooling the SuperBend dipoles on the LBNL Advanced Light Source.
KeywordsHeat Load Liquid Helium Lawrence Berkeley National Laboratory Heat Leak Liquid Cryogen
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