Air Force Research Laboratory Spacecraft Cryocooler Endurance Evaluation Update: FY98-99

摘要

The need for long term endurance evaluation data on space cryocoolers has long been an issue due to the 10-year plus design life of this technology and the absence of any accepted accelerated testing methodology. The Air Force Research Laboratory (AFRL), under sponsorship from the Ballistic Missile Defense Organization (BMDO), has been evaluating the long term performance of space cryocooler technology for the past five years to provide feedback to system designers and cryocooler developers to help mitigate or correct identified deficiencies. Cryocooler technology under evaluation at AFRL includes units from TRW, Creare, and Raytheon utilizing a variety of refrigeration cycles including Stirling, Pulse Tube (Stirling variant), Reverse Brayton cycles, and technological maturity. Cryocoolers are instrumented in state-of-the-art experiment stands utilizing software driven data acquisition systems that collect temperature, power, current, and voltage measurements. This allows critical cryocooler operating parameters to be closely tracked in order to quantify the technology's ability to meet the 5 to 10 year lifetime. It also allows AFRL to observe and document any long-term changes in cryocooler performance. Endurance data has been collected on 10 cryocoolers, some of which have been in operation for nearly 5 years. This paper includes experiment philosophy, lessons learned, and conclusions from the endurance evaluation program at AFRL for FY 98-99.