News & events
Painting it black | 28/01/2016
The MAST Upgrade vacuum vessel is getting a paint job – and its new look will ensure the experiment produces top-quality plasma physics data when it starts operating next year.
While it's a shame to cover up the gleaming stainless steel surfaces, science must take precedence over aesthetic considerations. A number of key measuring systems – ‘diagnostics' – on MAST-U will rely on accurate readings of light from the plasma. With uncovered steel, the light bounces off the vessel surfaces, playing havoc with the measurements. Reflected light also makes it more difficult to examine images of the plasma for physics phenomena such as 'ELM' instabilities. Applying graphite-based paint to the walls greatly reduces these reflections, giving physicists much better results to work with.
“The stray light confuses diagnostics that we use for information on plasma temperature, density and purity,” explains Neil Conway of the Diagnostics & Technical Support Unit. “It's like trying to hold a conversation with someone in a crowded room – the background noise makes it difficult to hear what the other person is saying. Blackening the walls massively improves our data.”
The redecoration means that MAST Upgrade can continue MAST's reputation as one of the world's best tokamaks for observing how plasmas behave – and provide us with many more beautiful images of fusion in action.
Image 1: Geoff Lee of CCFE's Engineering Installation Group spray-paints the inside of the MAST Upgrade vacuum vessel. For Geoff, a talented artist in his spare time, the job was an unusual way to apply his painting skills!
Image 2: A photograph of a typical plasma from the original MAST device, taken in 2013.