UK-based JET facility has more than doubled the world record for nuclear fusion energy generation set in 1997

The long-standing dream of using nuclear fusion to create a safe, efficient supply of energy has come closer to reality. Scientists at the Joint European Torus (JET) near Oxford have used their reactor to generate the largest-ever amount of energy in a sustained fusion reaction.

In an experiment carried out in December 2021, the team used JET to produce 59 megajoules of heat energy over a five-second period. The previous record of 22 megajoules was set by JET in 1997.

Computer graphic of the JET fusion reactor. The grey ball-shaped region in the centre is where the reactions take place, surrounded by magnetic coils that control the plasma. The orange-coloured transformer induces electric current in the plasma

“The record, and more importantly the things we’ve learned about fusion under these conditions and how it fully confirms our predictions, show that we are on the right path to a future world of fusion energy,” said Prof Tony Donné, EUROfusion programme manager. “If we can maintain fusion for five seconds, we can do it for five minutes and then five hours as we scale up our operations in future machines.”

Fusion is the process that takes place inside stars. It smashes together lighter atoms such as hydrogen at incredibly high temperatures to form heavier elements and release huge amounts of energy as heat.

The researchers say that the experiment’s success sets the scene for the International Thermonuclear Experimental Reactor (ITER), which is a larger, more advanced version of JET. ITER is a global fusion project based in Saint-Paul-lès-Durance, southern France. It involves scientists from China, the European Union, India, Japan, South Korea, Russia and the US. Although it is much larger than JET, ITER plans to use the same deuterium-tritium fuel source and operate under similar conditions when it goes online in 2025.

“This is a big moment for every one of us and the entire fusion community. Crucially, the operational experience we’ve gained under realistic conditions gives us great confidence for the next stage of experiments at ITER,” said Donné.

It is hoped that nuclear fusion will play an important role in addressing the effects of climate change, thanks to the low amounts of carbon it generates.

“It’s clear we must make significant changes to address the effects of climate change, and fusion offers so much potential,” said Prof Ian Chapman, the UK Atomic Energy Authority’s CEO.

“We’re building the knowledge and developing the new technology required to deliver a low-carbon, sustainable source of baseload energy that helps protect the planet for future generations. Our world needs fusion energy.”