A plasma coating to control the temperature of satellite components has been developed by the UK’s Sheffield Hallam University.
The plasma is designed to be applied to surfaces of cryocoolers – the devices that regulate the temperature of satellite systems, enabling on-board instruments to function most efficiently and gather higher-quality observational data about distant planets.
Cryocooling is critical to maintain the low operating temperature of detectors that are used to collect data from distant celestial objects and the Earth. Thermal noise reduces instrument sensitivity, while lowering thermal vibrations in optics ensures better image quality.
In addition, the low thermal conductivity of the vacuum operating environment in space means that satellite systems have to be cooled to prevent temperature build-up over years of use.
A team from Sheffield Hallam’s Nanotechnology Centre for Plasma Vapour Deposition worked with the Rutherford Appleton Laboratory’s Space Science Technology Department on the project.
RAL researchers had been investigating the potential for rare-earth coatings to enhance cooler performance, but had not been able to come up with a flightworthy solution.
RAL says that as a direct result of this collaboration its cryocooler “demonstrates a clear advantage” over other technologies for missions to observe the solar system and beyond.
The plasma is applied using an advanced technology for the deposition of very dense and highly-adherent metal and ceramic materials, called High Power Impulse Magnetron Sputtering.
HIPIMS is a physical vapour deposition process that uses very powerful short pulses of megawatts over tens of microseconds to vaporise and ionise solid metal targets in a vacuum.
The ionised vapour is then condensed onto the surface of a component to create a coating one atom at a time. Due to the high energy of the process, coatings are highly adherent, and have a dense microstructure with fewer imperfections, the team reports.
“These are coatings made up of special metals that belong to the rare earth group of elements,” explained the Sheffield Hallam project’s lead, Professor Arutiun Ehiasarian.
“Contrary to other materials, at low temperature their atomic structure spontaneously rearranges and becomes ordered. This results in these coatings being able to absorb more heat at low temperature.”