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Abstract

This paper describes the design, development, testing, and performance at Ball Aerospace of a longlife, 4-6 K temperature space cryocooler. For temperatures to 6 K and below, Ball has developed a hybrid Stirling/J-T (Joule-Thomson) cooler. The hybrid cooler has been verified in test to 3.5 K on a Ball program to study the J-T system, and a complete system test with the Stirling precooler and J-T cooling loop has been completed on the NASA/JPL Advanced Cryocooler Technology Development Program (ACTDP). This system test has shown that the Ball 4-6 K cooler can meet all the requirements of the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) cooler including a minimum 70mW at 6 K and 77 mW at 18 K. The ACTDP cooler provides simultaneous cooling at 6 K (typically for either doped Si detectors or as a precooler for a sub-Kelvin cooler) and 18 K (typically for optics or shielding) with cooling stages also available at 40 and 180 K (typically for thermal shields or other components). In the past year, the ACTDP cooler has become the baseline cooling method for the NASA JWST MIRI mission in addition to uses on several other future NASA missions. The 4-6 K Cooler is highly leveraged off previous Ball space coolers, including multiple life tests and flight units.