Limitless clean energy is a step closer to reality, after record-breaking nuclear fusion tests were completed at a UK laboratory.

Nuclear fusion – the process that powers the Sun and stars – was the focus of Joint European Torus (JET), one of the world’s largest and most powerful fusion machines.

Now it has shown it can reliably generate fusion energy, whilst also setting a world record in energy output.

Over 300 European scientists and engineers were involved in the landmark experiments, carried out at the UK Atomic Energy Authority (UKAEA) site in Oxford.

JET has played a major role in fusion energy over the last 40 years, as efforts continue to harness its endless power, generated with low carbon emissions.

It first demonstrated sustained fusion over five seconds at high power and set a world record in 2021.

Hailed as a “significant milestone in the field of fusion science and engineering”, the recent results “solidify JET’s pivotal role in advancing safe, low-carbon, and sustainable fusion energy”.

These achievements are also hailed as JET’s swansong, as its scientific operations ended in December.

UK Minister for Nuclear and Networks, Andrew Bowie, said, “JET’s final fusion experiment is a fitting swansong after all the groundbreaking work that has gone into the project since 1983. We are closer to fusion energy than ever before thanks to the international team of scientists and engineers in Oxfordshire.

The work doesn’t stop here. Our Fusion Futures programme has committed £650 million to invest in research and facilities, cementing the UK’s position as a global fusion hub.”

Professor Sir Ian Chapman, UKAEA CEO, said, “JET has operated as close to powerplant conditions as is possible with today’s facilities, and its legacy will be pervasive in all future powerplants. It has a critical role in bringing us closer to a safe and sustainable future.”

JET’s research findings have critical implications not only for ITER – a fusion research mega-project being built in the south of France – but also for the UK’s STEP prototype powerplant, Europe’s demonstration powerplant, DEMO, and other global fusion projects, all pursuing safe, low-carbon, and sustainable energy.

JET’s achievements

In JET’s final deuterium-tritium experiments (DTE3), high fusion power was consistently produced for 5 seconds, resulting in a ground-breaking record of 69 megajoules using only 0.2 milligrams of fuel.

JET is a tokamak – a design which uses powerful magnetic fields to confine a plasma in the shape of a doughnut. Most approaches to creating commercial fusion favour the use of two hydrogen variants – deuterium and tritium. When deuterium and tritium fuse together they produce helium and vast amounts of energy, a reaction that will form the basis of future fusion powerplants.

Professor Ambrogio Fasoli, Programme Manager (CEO) at EUROfusion, said, “Our successful demonstration of operational scenarios for future fusion machines like ITER and DEMO, validated by the new energy record, instill greater confidence in the development of fusion energy.

“Beyond setting a new record, we achieved things we’ve never done before and deepened our understanding of fusion physics.”

Dr Pietro Barabaschi, ITER Director-General, said, “Throughout its lifecycle, JET has been remarkably helpful as a precursor to ITER: in the testing of new materials, in the development of innovative new components, and nowhere more than in the generation of scientific data from Deuterium-Tritium fusion.

“The results obtained here will directly and positively impact ITER, validating the way forward and enabling us to progress faster toward our performance goals. On a personal note, it has been for me a great privilege having myself been at JET for a few years. There I had the opportunity to learn from many exceptional people.”

JET was honoured for its founding vision and successful collaboration in late February, as it moves into its repurposing and decommissioning phase. Its achievements, from reaching major scientific milestones to the setting of energy records, are its enduring legacy.