Protoflight Spacecraft Cryocooler Performance Results

Abstract

The Protoflight Spacecraft Cryocooler (PSC) is a flight-qualified Stirling cryocooler that delivers 1.2 W refrigeration at 35 K and 3 W refrigeration at 60 K. This Oxford-class unit employs three finger tangential flexures in the compressor module. These flexures have been shown to provide smoother, lower vibration piston motion than previously obtained with conventional three finger spiral flexures. Acceptance Tests validated the required performance capabilities and Qualification Tests validated the cooler for flight. Acceptance Tests included performance mapping at rejection temperatures from 275 K to 325 K, residual vibration measurements for each module, temperature stability under various conditions, cold tip motion, cold tip side load capacity. Qualification Tests included three-axis random vibration, thermal cycling, hermeticity and EMI/EMC tests. The 12.5 kg cooler was delivered with a brassboard command and control module that provides simultaneous temperature and Adaptive Feed-Forward vibration control. The PSC with brassboard electronics have been delivered to the Air Force Research Lab in Albuquerque, where additional testing has validated the results obtained at Raytheon.