Initial results from UK Atomic Energy Authority (UKAEA)’s new ‘MAST Upgrade’ experiment at Culham have demonstrated the effectiveness of the so-called Super-X divertor, an exhaust system that will allow components in future commercial tokamaks to last longer and bring costs down.
Inside a tokamak fusion reactor, light atomic nuclei are fused together to form larger ones, releasing a huge amount of energy in the process. This is achieved by confining plasma within a magnetic field and then heating it to temperatures of around 150 million degrees Celsius. The hot fusion plasma exhaust is then passed through a divertor to allow it to dissipate some of this excess heat.
Seven months of tests are said to shown at least a tenfold reduction in the heat on materials with the Super-X system.
UKAEA is planning to build STEP, a prototype fusion power plant, by the early 2040s using a compact ‘spherical tokamak’. The success of the Super-X divertor is encouraging as it is particularly suited to the spherical tokamak.
UKAEA announced the results at the official opening of the MAST Upgrade facility (May 26, 2021), which is funded by the UK government’s Department for Business, Energy & Industrial Strategy, the Engineering & Physical Sciences Research Council (EPSRC) and the EUROfusion consortium.
“We built MAST Upgrade to solve the exhaust problem for compact fusion power plants, and the signs are that we’ve succeeded,” said UKAEA’s lead scientist at MAST Upgrade, Dr Andrew Kirk. “Super-X reduces the heat on the exhaust system from a blowtorch level down to more like you’d find in a car engine. This could mean it would only have to be replaced once during the lifetime of a power plant.”