Description: Advanced space-borne instruments require cooling at temperatures of 10 K and below. These coolers will be used for as upper-stage cryocoolers for sub-Kelvin cryocoolers and instruments or the primary cooler for electro-optical instruments. Cooling loads for these detectors will range from 0.25 W to 1.0 W at the primary load site, with additional loads at higher temperatures for other subsystems. Due to jitter requirements, a cryocooler with very low vibration is required. In addition, a multistage cooler, capable of providing refrigeration at more than one temperature simultaneously, can provide the greatest system efficiency and lowest mass. Turbomachine-based Brayton cryocoolers are ideal candidates for these applications because they are highly efficient, lightweight, vibration-free, multistage compatible, and have long maintenance-free lifetimes. Creare has developed state-of-the-art components needed to create turbo-Brayton cryocoolers for these missions. During the current program, we propose to develop and demonstrate a two-stage cryocooler that provides refrigeration at 10 K, with additional cooling at 60 to 70 K. On the Phase I project, we will optimize the performance of an existing cryocooler for a particular NASA mission class and measure its performance. During the Phase II project, we plan to build an advanced cold-stage turboalternator, integrate it with the cryocooler and measure its performance at cold load temperatures as low as 10 K. We will use the test results to develop a design for a fully optimized, flight cryocooler.

Benefits: The successful completion of this program will result in the demonstration of an extremely efficient low temperature cryocooler with negligible vibration. This type of cryocooler is ideal for cooling applications in space-based observation, surveillance and missile defense systems. Government-funded scientific applications include space-based infrared and X-ray observatories.

Commercial applications include communication satellites, superconducting instruments, hypercomputers, and Superconducting Quantum Interference Devices (SQUIDs).