Introduction: Improving Thermal Conductivity
ALLVAR is excited to announce that ALLVAR Alloys will be used in their first ever flight application for a NASA mission. Specifically, ALLVAR Alloy 30 washers are being integrated into the Cryogenic Thermal Subsystem that cools the Coronagraph Instrument on the Nancy Grace Roman Space Telescope. Learn more about how ALLVAR Alloys are being used to improve thermal conductivity below.
ALLVAR Alloys enhancing space materials
Recently, Space Dynamics Laboratory (SDL) publicly announced their delivery of the Cryogenic Thermal Subsystem to NASA’s Jet Propulsion Laboratory (JPL). The subsystem, and thus the ALLVAR Alloy washers, are being evaluated at JPL prior to the subsystem’s integration into the Nancy Grace Roman Space Telescope’s Coronagraph Instrument.
ALLVAR Alloy 30 washers helped SDL engineers use their new Pyrolytic Graphite Sheet material to make thermal straps in the Cryogenic Thermal Subsystem. Thermal straps are necessary to effectively conduct heat away from the Coronagraph cameras enabling them to take high resolution pictures that can detect habitable planets orbiting distant stars. Pyrolytic Graphite has a very high thermal conductivity and low weight which makes it a great space material for thermal control.
ALLVAR Alloy 30 washers make sure thermal straps maintain just the right contact pressure during cryogenic cooling. The result is a smaller and lighter design enabled by Pyrolytic Graphite and good thermal connections supported by ALLVAR Alloy washers.
Images courtesy of NASA. Left image from “The Coronagraph Instrument – Reference Information” February, 2021 presentation. Right image from “Mission and Observatory” technical information.
ALLVAR Alloy Washers for Improved Thermal Conductivity
The virtues of ALLVAR Alloy 30 washers maintaining the right force across temperature changes has been detailed here and here. ALLVAR Alloy washers enable the “Goldilocks” of bolted joints designed for temperature extremes. When using ALLVAR Alloy washers, bolted joints are not too-tight or too-loose; they’re just right, even at cryogenic temperatures.
This is especially important in applications like thermal straps where thermal conductance is essential. If the contact pressure of a thermal strap’s bolted joint decreases at cryogenic temperatures, the thermal path is disrupted and the thermal contact conductance decreases. This significantly decreases the performance of a cryo-cooled system. ALLVAR Alloys washers offer a more reliable and smaller alternative to traditional thermal conductivity solutions like spring and Bellville washers.
What is a coronagraph anyway?
A coronagraph is a special instrument that blocks out the direct light from a star so images can be taken of things that surround the star. This is the same principle that allows you to see around you more clearly on a sunny day by blocking the sun with your hand. Another natural example of this in action is a total eclipse where the moon blocks out direct sunlight and incredible pictures of solar flares and other phenomena can be captured.
The coronagraph on the Nancy Grace Roman Space Telescope will block the direct sunlight of far distant stars so that planets that orbit those stars can be detected. What’s more is the detector will be able to detect the atmospheric composition of these far away planets. Understanding a planet’s atmosphere will enable astrophysicists to determine if the distant planet could be habitable.
Ready to improve thermal conductivity or maintain more consistent forces?
ALLVAR’s ready to help your bolted joints stay in the ‘Goldilocks Zone’. Not too tight and not too loose no matter the temperature! Negative CTE Washers and Spacers are now available. Select sizes even include commercially-off-the-shelf pricing. Find out more here.
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