Advanced Multi-stage Cryogenic Cooling Technology

"Many advanced space-based reconnaissance systems critical to national security employ infrared detectors, optics, and thermal baffles that require multi-stage cooling. If cryocoolers such as Stirlings with single point cooling are used, then multiplecoolers will be required that impose mass, power, volume, and reliability penalties; redundancy further increases these penalties. These penalties can be mitigated through the use of a single cryocooler with multiple cooling stages, thereby also reducingthe number of compressors and electronic controllers. The objective of the Phase I study is to develop and demonstrate the feasibility of a Multi-Stage Brayton Cryocooler (MSBC) with simultaneous cooling capacities of 6 W at 85 K and 2 W at 35 K. Thecryocooler system will be highly leveraged off components currently under development: a micro-electro-mechanical system (MEMS) based expander, an oil-free scroll compressor, and a high effectiveness counterflow heat exchanger. The MSBC's operationalcapabilities include significant integration advantages: the cooling fluid can be circulated over long distances providing isolation from cooler-induced interference, variable load capability, and a distributed cold-head that can accommodate large arefocal pane assemblies (FPA). These features and capabilities will significantly reduce satellite power and heat rejection requirements, decrease overall weight, and greatly simplify cooling system