Flight demonstration of the ball Joule-Thomson cryocooler

The Ball Joule-Thomson (J-T) cryocooler has been under development for over 10 years and has achieved a high level of technical maturity. The Cryogenic On-Orbit Long-Life Active Refrigerator (COOLLAR) program developed two protoflight versions of the J-T cryocooler. One version is the Engineering Development Model (EDM). This cryocooler consists of an oil-lubricated compressor with a gas purification system that provides ultra-pure nitrogen to the cold head. The cold head produces liquid nitrogen to provide two stages of constant temperature cooling for varying loads. The cold stage provides 3.5 W of cooling at 65 K, and the intermediate stage provides 5 W of cooling at 120 K. The COOLLAR Flight Experiment (CFE) program night tested the EDM J-T cryocooler to verify microgravity performance. The cryocooler was flown on STS-85 aboard the space shuttle Discovery on the Technology Applications and Science 1 (TAS-1) experiment bridge. This paper presents the results of the flight experiment. All of the experiment objectives were accomplished, and all operating principles were demonstrated in this mission. The data shows that there are no functional performance differences between ground and flight operation. On-orbit performance robustness and adaptability useful to future applications have been demonstrated.