Development of a Periodic 10 K Hydrogen Sorption Cryocooler
The design and fabrication of a small, closed-cycle, periodic 10 K sorption cryocooler laboratory system is described. The cooler is designed to provide cooldown from 60 to < 10 K in under 2 minutes, maintain a simulated detector heat load of 100 mW below 10 K for over 10 minutes, and have the ability to be recycled in under 6 hours. A LaNi4.8Sn0.2 hydride sorbent bed is used to compress and circulate hydrogen refrigerant in the 24–30 K Joule-Thomson intermediate refrigeration stage. A ZrNi hydride sorbent bed is used to provide the low vacuum pressure (< 2 torr) needed to solidify and cool the hydrogen to 10 K. Thermally cycling the sorbent beds between 290 and 550 K produces a compression ratio of nearly 106. A vacuum-pumped liquid nitrogen loop is used to simulate a mechanical cooler or radiator for the upper 60–80 K stage. Performance predictions are presented, results are compared with ground test data from the flight-qualified Brilliant Eyes Ten-Kelvin Sorption Cryocooler Experiment (BETSCE), and plans for using the cooler as a test bed for future reliability physics experiments are described. Performance and reliability test results, combined with BETSCE flight validation data, will enable early insertion of this long-life (> 10 years), low-vibration refrigeration technology into precision-pointing military surveillance, earth-observation, and astrophysics space satellite applications.
KeywordsMigration Epoxy Hydride Beryllium Refrigeration
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