Advanced Multistage Technology for 10-Kelvin Space-Borne Cryocoolers

Advanced space-borne infrared sensor technology requires cooling at temperatures near 10 K. Cooling loads for these detectors will range from 0.25 to 1.0 W at 10 K, with additional loads at higher temperatures. A multistage cooler, capable of coolingmultiple loads, will offer large potential gains in system efficiency and weight. Turbomachine-based, Brayton cryocoolers are ideal candidates for these missions because they are highly efficient, lightweight, vibration-free, adaptable to multiple stages,and have long, maintenance-free lifetimes. State-of-the-art technology exists for all the critical components except for a 10 K turboalternator. Creare proposes to develop an advanced, high-efficiency turboalternator optimized for a multistage,multi-load application. The advanced turboalternator will enable a significant reduction in cryocooler input power and overall cooling system mass. In Phase I, we performed trade studies to determine an optimum multistage, multi-load cryocoolerconfiguration for a specific Air Force application, and determined that significant weight and power savings were possible with this configuration. We then developed a conceptual design for this cryocooler, and a preliminary design of an advancedlow-temperature turboalternator. In Phase II, we will fabricate this turboalternator and demonstrate its performance at prototypical operating conditions.