Other
Scientific paper
Aug 2005
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005spie.5904..120b&link_type=abstract
Cryogenic Optical Systems and Instruments XI. Edited by Heaney, James B.; Burriesci, Lawrence G. Proceedings of the SPIE, Volume
Other
Scientific paper
This paper describes two cryogenic thermal switches (CTSWs) under development for instruments on the James Webb Space Telescope (JWST). The first thermal switch was designed to extend the life of the solid H2 dewar for the 6 K Mid Infrared Instrument (MIRI) while the second thermal switch is needed for contamination and over-temperature control of three 35 K instruments on the Integrated Science Instrument Module (ISIM). In both cases, differential thermal expansion (DTE) between two materials having differing CTE values is the process that underpins the thermal switching. The patented DTE-CTSW design utilizes two metallic end-pieces, one cup-shaped and the other disc-shaped (both MIRI end-pieces are Al while ISIM uses an Al/Invar cup and an Al disc), joined by an axially centered Ultem rod, which creates a narrow, flat gap between the cup (rim) and disc. A heater is bonded to the rod center. Upon cooling one or both end-pieces, the rod contracts relative to the end-pieces and the gap closes, turning the CTSW ON. When the rod heater is turned on, the rod expands relative to the end-pieces and the gap opens, turning the CTSW OFF. During testing from 6-35 K, ON conductances of 0.3-12 W/K and OFF resistances greater than 2500 K/W were measured. Of particular importance at 6 K was the Al oxide layer, which was found to significantly decrease DTE-CTSW ON conductance when the mating surfaces were bare Al. When the mating surfaces were gold-plated, the adverse impact of the oxide layer was mitigated. This paper will describe both efforts from design through model correlation.
Beres Matthew
Bugby David
Rodriguez Jose
Stouffer Charles
No associations
LandOfFree
Advanced cryogenic thermal switches for JWST does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Advanced cryogenic thermal switches for JWST, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Advanced cryogenic thermal switches for JWST will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-802425