Air Force Research Laboratory Cryocooler Reliability Initiatives

Abstract

The primary concern of spacecraft developers when considering active refrigeration for space missions is lifetime and reliability. Lack of confidence in current cryocooler technology to achieve mission performance goals and achieve the necessary lifetime is a deterrent that often precludes the consideration of cryocooler technology for many space applications.

The Air Force Research Laboratory (AFRL), through the Georgia Tech Institute of Technology, has conducted two workshops with government and industry developers and technology users to address cryocooler reliability. These workshops highlighted critical issues associated with mechanical, electronic, and software reliability for cryocooler systems. Also addressed were issues on contamination control, performance testing, acceptance testing, manufacturing in-process testing, environmental qualification screening, endurance evaluation and demonstration, and producibility issues.

In addition, AFRL has pursued research and development efforts to augment cryocooler technology development with the aim of increasing reliability. Efforts such as vibration mitigation through improved compressor design, improved flexure bearings, reduced gas contamination, and potential accelerated testing approaches have been explored.

AFRL in-house laboratory characterization and endurance evaluation of cryocooler technology has also contributed to the lifetime and reliability database for emerging technologies. This information is invaluable as a tool for spacecraft developers to understand the lifetime and reliability potential of a candidate cryocooler technology and establish a heritage database for cryocooler families. Additionally, AFRL has made direct contributions to improvements in follow-on designs through the feedback of performance and endurance data to industry developers.