Cryogenic Advanced Loop Heat Pipe in Temperature Range of 20-30K

The Next Generation Space Telescope (NGST) program has identified the need for cryogenic cooling transport devices that can provide cryogenic cooling in the temperature range of 20-30K, minimize vibration effects of cryocoolers on instruments, minimize spatial temperature gradient in cryogenic components, level out thermal loads from duty-cycled components, enable locating cryocoolers remotely from instruments, and share cooling power of a cooling source among instruments. The proposed Cryogenic Advanced Loop Heat Pipe (CALHP) with hydrogen working fluid will accommodate all stated requirements. It solves the difficult problem of managing parasitic heat gain in the liquid line, which severely limits the cryogenic capillary pumped loop, by using a secondary pumping system that effectively removes the heat gain. It also enables operation at lower temperatures. The CALHP then does not require liquid cooled shielding which is required for the cryogenic CPL, where the liquid line is looped around the condenser several times to cool the shield. This also means that the CALHP transport section can be made flexible by limiting the number of lines passing through the interface.