Positive results from UK plasma exhaust research

27 May 2021

Initial results from the UK Atomic Energy Authority's (UKAEA's) new MAST Upgrade experiment at the Culham Centre for Fusion Energy (CCFE) in Oxfordshire, England, have demonstrated the effectiveness of an innovative exhaust system designed to make compact fusion power plants commercially viable. The new exhaust system - called the Super-X divertor - is designed to channel plasma out of the machine at temperatures low enough for its materials to withstand - meaning that components can last much longer.

Interior of the MAST Upgrade spherical tokamak (Image: UKAEA)

Using a machine called a 'tokamak', a fusion power station will heat a gas, or 'plasma', enabling types of hydrogen fuel to fuse together to release energy that can generate electricity. A key challenge to commercialising tokamaks is the removal of excess heat produced during fusion reactions. Without an exhaust system that can handle this intense heat, materials will have to be regularly replaced - significantly affecting the amount of time a power plant could operate for.

Tests at MAST Upgrade, which began operating in October 2020, have shown at least a tenfold reduction in the heat on materials with the Super-X system. This system is designed to cool particles down by steering them on a longer exhaust path out of the plasma.

"This is a game-changer for achieving fusion power plants that can deliver affordable, efficient electricity," CCFE said.

The Super-X divertor system, it said, would allow components in future commercial tokamaks to last for much longer, greatly increasing the power plant's availability, improving its economic viability and reducing the cost of fusion electricity.

"These are fantastic results. They are the moment our team at UKAEA has been working towards for almost a decade," said UKAEA’s Lead Scientist at MAST Upgrade, Andrew Kirk. "We built MAST Upgrade to solve the exhaust problem for compact fusion power plants, and the signs are that we've succeeded.

"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. It's a pivotal development for the UK's plan to put a fusion power plant on the grid by the early 2040s - and for bringing low-carbon energy from fusion to the world."

UKAEA announced the results at yesterday's official opening of the MAST Upgrade facility, where guest of honour, British astronaut Tim Peake, created his own artificial 'star' by running a plasma test on the machine.

MAST Upgrade is based on the original MAST (Mega Amp Spherical Tokamak) machine, which ran from 2000 to 2013. It has been rebuilt to enable higher performance - longer pulses, increased heating power and a stronger magnetic field. The project is funded by the UK's Department for Business, Energy & Industrial Strategy, the Engineering & Physical Sciences Research Council and the EUROfusion consortium.

MAST Upgrade will be the forerunner of the UK's prototype fusion power plant - Spherical Tokamak for Energy Production (STEP) - due for completion by 2040. The UKAEA is designing STEP in an initial GBP220 million (USD312 million) programme funded by the UK government and based on MAST Upgrade's spherical tokamak fusion concept.

Researched and written by World Nuclear News