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. The satellites carrying these sensors also have additional cooling loads at differenttemperatures. A multistage cooler capable of cooling multiple 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, highefficiency turboalternator optimized for a multistage, multi-load application to be identified by the Air Force. The advanced turboalternator promises to enable a significant reduction in cryocooler input power and cooling system mass. In Phase I we willselect an optimum multistage, multi-load cooling cycle based on analysis and trade studies. We will then design a turboalternator for these specific conditions. In Phase II we will fabricate the turboalternator and conduct a series of tests todemonstrate its performance and to address the specific technology challenges in a multistage multi-load cycle. The development of advanced low-temperature turboalternators will enable the development of high-effic