Miniature 30K Cryocooler

West Coast Solutions (WCS) and the Georgia Institute of Technology (GT) propose the development of a Miniature Stirling / Pulse Tube 30K Cryocooler in response to Topic S16.07, Cryogenic Systems for Sensors and Detectors. The proposed effort is essentially the miniaturization of the cryocooler demonstrated on the 2024 NASA Phase I SBIR Sub-10K Cryocooler program, on which 4.88K was achieved with a similar but larger hybrid Stirling / pulse tube 2-stage cryocooler. WCS proposes to leverage miniaturization techniques from our ongoing Missile Defense Agency (MDA) Sequential Phase II SBIR SmallSat Stirling Cryocooler (SSC-X) program to achieve this end. While the target operating point for the proposal is single-stage cryocooling at 30K per the Topic objectives, the use of a two-stage hybrid Stirling/pulse tube cold head provides operational flexibility to meet a wide range of mission needs, including those benefiting from two stages of cooling and/or utilizing an upper stage to intercept parasitic loads on the lower stage. The use of a Stirling first stage enables high thermodynamic efficiency while the addition of a pulse tube provides a distinct second stage with no additional moving parts, no additional failure mechanisms, no fundamental changes to the upper stage and essentially the same drive electronics, i.e., the 30K target is met with essentially the same mechanical complexity as a single-stage cooler. During the proposed Phase I, WCS and GT will complete the detailed thermodynamic/fluidic design of a miniature, high-efficiency 30K cryocooler based on the Stirling / pulse tube hybrid architecture, an inherently flexible architecture that broadens the applicability well beyond 30K. The analytical models will be supported by and shown consistent with preliminary solid models to help reduce implementation risk. WCS also proposes under Phase I to perform preliminary performance testing of the pulse tube (2nd) stage.
Benefits: With the challenges of miniaturization, efficiency, multi-stage cooling, and operation over a wide temperature range all addressed, success on the Mini 30K cryocooler will enable use of advanced heterodyne receivers and other low temperature detector technologies on very compact buses. Benefitting detectors also include the most commonly used HgCdTe LWIR detectors (35K, typical) as well as other longwave detector technology, such as the quantum well infrared photodetector (QWIP) used on the Landsat Thermal Infrared Sensor (TIRS) instrument . The proposed effort is also relevant to bolometric focal plane arrays made from high temperature superconductors . In addition to supporting immediate NASA needs by addressing a specific S16.07 technical requirement, implementing the hybrid cold head technology into a miniaturized cryocooler system opens up opportunities for an entirely new class of multistage cryocooler systems for small satellites (SmallSats), which are of ever-increasing interest for the Department of Defense (DoD) as it pursues its Resiliency through Disaggregation agenda.