CRYOGENICS CAPABILITIES

The two-story-high Cold Box valve platform resides above the Cold Box vacuum shell. The opening of the vacuum shell removal floor pit can be seen below the shell.

The Center features one of a class of only five helium refrigerator/liquefier facilities in the world capable of meeting the requirements of multiple large- or small-scale simultaneous cryogenics uses. This facility, currently uncommitted and available, is of the latest design and provides optimal system efficiency, load flexibility, and performance tracking.

Three large-capacity refrigerators with supporting cryogenic equipment are available to support research and to perform component and system testing over a wide range of cryogenic conditions. The three refrigerators can be operated independently or in transfer-line combinations supplying up to 12 kW at 4.5 K. One of the refrigerators is capable of operating at temperatures down to 2.5 K. Some of these existing cryogenic systems could also be modified at a modest cost to provide a 1.8 K (superfluid) capability.

Each of the three large-capacity helium refrigerators is optimized to deliver 2.2 kW of refrigeration and 22 g/s liquefaction at 4.5 K. Each system can, however, deliver up to 4 kW of refrigeration or 37 g/s liquefaction at 4.5 K. The MDL system pump box can provide supercritical flows up to 600 g/s at 4.6 K, or subatmospheric temperatures at any one of five test stands using warm vacuum pumps and refrigeration recovery; e.g. 50 g/s at 2.5 K to each of two test stands (to 102 W), or 100 g/s at 3.6 K to each of three test stands (to 153 W). The ASST system can provide up to 180 g/s flow at 4.5 K, or 100 g/s at 3.5 K (to 500 W) with the use of two cold compressors.

The operation of each refrigerator/liquefier system is supported by dedicated cryogenic equipment consisting of four main compressors, a compressor oil removal system, a cold box with dual absorbers and four turbo-expanders, a 40,000 liter LHe dewar with intergral subcooling and sparging lines, and warm gas storage capacity. Each of these systemsc is also supported by its own clean-up, cool-down, warm-up, and purification (CCWP) system and an 80,000 liter LN2 dewar with gas purging and distribution.