Development of 1K-class Joule–Thomson cryocooler for next-generation astronomical mission

•This paper reports on development of a 1K-class Joule Thomson cryocooler in Japan.•Engineering models was fabricated for several verification tests.•Survivability of the JT compressors in mechanical and thermal vacuum environment was confirmed.•Nominal cooling power of 10 mW at 1.7 K with 3He gas was verified and lifetime test began May 2015.

This paper reports on the development of a 1K-class Joule–Thomson (JT) cryocooler in Japan for application to upcoming next-generation astronomy missions. In this development, engineering models (EMs) were designed and manufactured for verification tests. The survival of the models in the mechanical and thermal vacuum environment tests of the JT compressors was proven to be possible with stable compression performance. In addition, the electromagnetic noise and disturbance force associated with the JT compressors were evaluated. Gas analysis showed that the estimated total amount of CO2 gas contaminant was less than the getter capacity for the required lifetime. A nominal cooling power of 10 mW at 1.7 K was verified using the EM test units.