Development of a High Capacity 35 K Multistage Turbo-Brayton Cryocooler

"We propose to develop an innovative high capacity multistage cryocooler for dual cooling loads at temperatures of 85 K and 35 K. The cooler is based on proven turbo-Brayton technology that has been flight demonstrated and qualified for use on the HubbleSpace Telescope (HST). This technology will be adapted to the unique requirements of DoD infrared sensor applications at lower temperatures and at significantly increased cooling powers. The proposed system will be capable of simultaneously providing 2 Wof refrigeration at 35 K and 20 W at 85 K within a single integrated assembly. The unique characteristics of the turbo-Brayton cycle permit distributed cooling at multiple sites with a single, multistage configuration with very high thermodynamicefficiency, resulting in low input power and reduced mass. In Phase I, system trade studies will be performed leading to a Preliminary Design Review of the optimized cycle. Phase II will produce a complete detailed design of the system, culminating in aCritical Design Review. The system relies on innovative high speed miniature turbomachines to provide long life with negligible vibration. A high capacity multistage turbo-Brayton cryocooler addresses a near-term DoD need for cooling space-based infraredsurveillance sensors where multiple loads must be accommodated on a single platform. A multistage cooler eliminates the need for several separate coolers, reducing system mass, input power,