Test Results for a Commercial, Low Vibration, Linear, Stirling Cycle Cryocooler

NASA/GSFC personnel have evaluated a commercial, low vibration, linear motor driven Stirling cryocooler made by Sunpower Inc. for potential space use on long duration space flight missions. NASA, the U.S. Air Force and industry have invested considerable money during the last decade to develop low vibration mechanical cryocoolers for space applications with typical lifetimes of five years or more. Present space-based cryocoolers typically cost about $1 million per cryocooler. As a potential alternative for one to three year space flight missions, NASA/GSFC has purchased and evaluated eight identical commercial cryocoolers manufactured by Sunpower, Inc. These cryocoolers were designed to have an operational life of greater than 50,000 hours. The cryocooler is an integral Stirling cycle, free piston displacer using linear drive motors for a single compressor and single counterbalancer. Characterization tests include load curves, power measurements, thermal vacuum testing and axial and lateral vibration measurements with and without an active vibration control system. Launch vibration and preliminary life test data will also be presented.