MID INFRARED INSTRUMENT (MIRI) COOLER SUBSYSTEM PROTOTYPE DEMONSTRATION

The Cooler Subsystem for the Mid InfRared Instrument (MIRI) of the James Webb Space Telescope (JWST) features a 6 Kelvin Joule-Thomson (JT) cooler pre-cooled by a three-stage Pulse Tube (PT) cryocooler to provide 65 mW of cooling at the instrument. MIRI's 6 Kelvin cooling load, directly behind the primary mirror of JWST, is remote from the location of the compressors and pre-cooler. This distance, and the parasitic heat load on the refrigerant lines spanning it, is accommodated by the design. The effort during 2006 and the first part of 2007 has focused on the demonstration of a MIRI Cooler prototype in the relevant environment, required to achieve Technology Readiness Level 6 (TRL 6) as defined by NASA[1]. The tests that have been used to successfully demonstrate TRL 6: launch vibration and cooler performance in the relevant thermal-vacuum environment, will be discussed.