West Coast Solutions (WCS), Creare LLC, and the Georgia Institute of Technology (GT) propose the development of a Miniature 2-Stage Hybrid (M2H) Cryocooler in response to Topic S1.09, Miniaturized/Efficient Cryocooler Systems. Extending from our prior NASA and ongoing Missile Defense Agency (MDA) SmallSat Stirling cryocooler developments, we propose to add a second stage to address the topic requirements for a highly-miniaturized, two-stage cryocooler. In Phase I we will mature the concept design of a Stirling/pulse tube hybrid expander that achieves extreme miniaturization by leveraging our high resonant frequency mechanism and low impedance regenerator designs. Based on initial modeling results, the WCS M2H Cryocooler will weigh less than 1.5 kg while simultaneously providing a minimum of 1 Watt of net refrigeration at 80K and 2 Watts of refrigeration at 140K. The projected input power is 32 WAC while operating in a 300K heat rejection environment, which translates to 15.6% of Carnot efficiency.
The immediately benefitting NASA applications are midwave to longer wavelength infrared sensors requiring two stages of cryogenic refrigeration. Typically this means that the FPA is cooled to one temperature, say 80K, while the optics are cooled to higher yet still very cold temperature, say 140K to 160K, to reduce the background signal from the otherwise warm optics. With this technology readily extensible to 30K detector cooling, this proposal also supports VLWIR sensor cooling.
The non-NASA applications are essentially the same, but for different missions. Whereas the NASA applications are expected to support IR spectrometers for Earth imaging, planetary exploration on small satellites, etc., DoD is very interested in this technology for ballistic missile launch detection and other traditional military applications.