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Fusion research facility JET’s final tritium experiments yield new energy record

Reports and Proceedings


JET DTE3 Record Pulse - image 1


Looking inside the Joint European Torus tokamak at pulse #104522 from 3 October 2023, which set a new fusion energy record of 69 megajoules.

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Credit: © United Kingdom Atomic Energy Authority, courtesy of EUROfusion

GARCHING and OXFORD (8 February 2024) –

The Joint European Torus (JET), one of the world’s largest and most powerful fusion machines, has demonstrated the ability to reliably generate fusion energy, whilst simultaneously setting a world-record in energy output.

These notable accomplishments represent a significant milestone in the field of fusion science and engineering.

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 a mere 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.

Dr Fernanda Rimini, JET Senior Exploitation Manager, said:

“We can reliably create fusion plasmas using the same fuel mixture to be used by commercial fusion energy powerplants, showcasing the advanced expertise developed over time.”

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, instil 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 Emmanuel Joffrin, EUROfusion Tokamak Exploitation Task Force Leader from CEA, said:

“Not only did we demonstrate how to soften the intense heat flowing from the plasma to the exhaust, we also showed in JET how we can get the plasma edge into a stable state thus preventing bursts of energy reaching the wall. Both techniques are intended to protect the integrity of the walls of future machines. This is the first time that we've ever been able to test those scenarios in a deuterium-tritium environment.”

Over 300 scientists and engineers from EUROfusion – a consortium of researchers across Europe, contributed to these landmark experiments at the UK Atomic Energy Authority (UKAEA) site in Oxford, showcasing the unparalleled dedication and effectiveness of the international team at JET.

The results solidify JET’s pivotal role in advancing safe, low-carbon, and sustainable fusion energy.

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.”  

JET concluded its scientific operations at the end of December 2023.

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, pursuing a future of safe, low-carbon, and sustainable energy.

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 has been instrumental in advancing fusion energy for over four decades, symbolising international scientific collaboration, engineering excellence, and the commitment to harness the power of fusion energy – the same reactions that fuel the Sun and stars.

JET demonstrated sustained fusion over five seconds at high power and set a world-record in 2021. JET’s first deuterium-tritium experiments took place in 1997.

As it transitions into the next phase of its life cycle for repurposing and decommissioning, a celebration in late February 2024 will honour its founding vision and the collaborative spirit that has driven its success.

The achievements at JET, from the major scientific milestones to the setting of energy records, underscores the facility’s enduring legacy in the evolution of fusion technology.

Its contributions to fusion science and engineering have played a crucial role in accelerating the development of fusion energy, which promises to be a safe, low carbon and sustainable part of the world’s future energy supply.


- ENDS -


Fusion energy’s potential

Fusion, the process that powers stars like our sun, promises a clean baseload source of heat and electricity for the long term, using small amounts of fuel that can be sourced worldwide from inexpensive materials.

When a mix of two forms of hydrogen (deuterium and tritium) is heated to form a controlled plasma at extreme temperatures – 10 times hotter than the core of the Sun – they fuse together to create helium and release energy which can be harnessed to produce electricity.

Deuterium and tritium are two heavier variants of ordinary hydrogen and together offer the highest reactivity of all fusion fuels. At a temperature of 150 million degrees Celsius, deuterium and tritium fuse together to form helium and release a tremendous amount of heat energy without any greenhouse contributions. Fusion is inherently safe in that it cannot start a run-away process and produces no long-lived waste.

There is more than one way of achieving fusion. Our approach is to hold the hot plasma using strong magnets in a ring-shaped machine called a ‘tokamak’, and then to harness this heat to produce electricity in a similar way to existing power stations.

About the fusion energy fuel

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.

Deuterium is plentiful and can be extracted from water. Tritium is a radioactive variant of hydrogen with a half-life of about 12 years. Tritium can be farmed from lithium.

About the final deuterium-tritium experiments (DTE3)

JET is the only tokamak fusion machine in operation capable of handling tritium fuel. The third round of experiments using deuterium and tritium fuel were conducted over seven weeks from 31st August to 14th October 2023. They focused on three areas – plasma science, materials science and neutronics.

JET's fusion energy record is a result of the advanced capability in operating deuterium-tritium plasmas. These experiments were primarily designed as the first-ever opportunity to demonstrate the feasibility of minimising heat loads on the wall in a deuterium-tritium environment, crucial for ITER scenarios.

To learn more about the scientific results of the JET DTE3 experiments, please visit:
Joint European Torus successfully tests new solutions for future fusion power plants

40 years of fusion science

JET has been the largest and most successful fusion experiment in the world, and a central research facility of the European Fusion Programme. JET is based at the UKAEA campus in Culham, UK and has been a collective facility used by more than 31 European laboratories under the management of the EUROfusion consortium—experts, students and staff from across Europe, co-funded by the European Commission.

Since its inception in 1983 as a joint European project, JET has been at the forefront of groundbreaking achievements, spearheading the pursuit of safe, low-carbon, and sustainable fusion energy solutions to meet the world's future energy demands.

Over its lifetime JET has delivered crucial insights into the complex mechanics of fusion, allowing scientists to plan the international fusion experiment ITER and DEMO, the demonstration fusion power plant currently under design by the European fusion community.

Built by Europe and used collaboratively by European researchers over its lifetime, JET became UKAEA property in October 2021, celebrated its 40th anniversary in June last year, and ceased plasma operations at the end of 2023.

About EUROfusion

EUROfusion, the European Consortium for the Development of Fusion Energy, is at the forefront of advancing fusion technology with the goal of establishing fusion as a safe, sustainable, and economically viable source of energy. It champions the pursuit of fusion as a large-scale, sustainable energy source through its coordination of Europe's fusion research activities.

Operating under the Euratom Research and Training Programme, EUROfusion advances fusion technology and research across eight key missions, as detailed in the European Fusion Research Roadmap. The programme is dedicated to paving the way for fusion power plants, leveraging collaborative research and innovation to overcome the technical and scientific challenges of harnessing fusion energy. This effort is epitomized by EUROfusion's joint and very successful exploitation of fusion experimental machines across Europe, including the operation of JET until the end of 2023, showcasing a unique and concrete contribution to fusion science. This includes preparation for the scientific exploitation of ITER, as well as laying the technological groundwork for DEMO, the planned demonstration fusion power plant.

EUROfusion's commitment extends to fostering the next generation of European fusion researchers, ensuring a skilled workforce for ITER and future machines. By integrating efforts across 195 research entities in 29 European countries, EUROfusion is actively shaping the future of energy, emphasizing safety, sustainability, and economic viability in fusion technology.

For more insights into our mission and progress, visit our website and connect with us on LinkedIn, Facebook, and X (Twitter).

About Euratom

The Euratom Research and Training Programme (2021-2025) is a complementary funding programme to the EU Horizon Europe Programme. It is dedicated to nuclear research and innovation in fission and fusion. The Euratom Programme includes both direct actions undertaken by the European Commission's Joint Research Centre, and indirect actions conducted by multi-partner consortia. One example is EUROfusion, responsible for implementing Europe-wide fusion research.

With a budget of €1.38 billion for the period 1 January 2021 to 31 December 2025, the Euratom Research and Training Programme is focused on the continuous improvement of nuclear safety, security, and radiation protection, as well as fusion energy research. €583 million is dedicated to indirect actions on fusion research and development.

For more information: Euratom Research and Training Programme

Social Media: @EUScienceInnov

About UK Atomic Energy Authority

United Kingdom Atomic Energy Authority (UKAEA) is the UK’s national organisation responsible for the research and delivery of sustainable fusion energy. It is an executive non-departmental public body, sponsored by the Department for Energy Security and Net Zero.

Fusion energy has great potential to deliver safe, sustainable, low carbon energy for generations to come. It is based on the same processes that power the Sun and stars, and would form part of the world’s future energy mix. Achieving this is a major technical challenge that involves working at the forefront of science, engineering, and technology.

UKAEA's fusion machines include MAST-Upgrade (Mega Amp Spherical Tokamak) and the JET (Joint European Torus) research facility. JET's operations were funded by the UK Government from 2021 until 31st December 2023. UKAEA is delivering the transition of JET from plasma operations to repurposing and decommissioning, on behalf of the UK Government. The insights gained from this process will contribute to the advancement of sustainable future fusion powerplants.

UKAEA is implementing the UK’s £650 million Fusion Futures Programme, the UK's alternative programme to associating to Euratom R&T, to support the UK Fusion Strategy. The Programme entails establishing new facilities at UKAEA’s Culham Campus in Oxfordshire to facilitate the advancement of new technologies and expand fusion fuel cycle capabilities. The Programme aims to foster world-leading innovation while also stimulating general industry capacity through international collaboration and the development of future fusion powerplants. Additionally, a fusion skills package will be introduced focusing on nurturing expertise across a spectrum of disciplines and levels. In 2021, UKAEA opened its Fusion Technology Facility near Rotherham in South Yorkshire, to develop and test materials and components for future fusion powerplants.

UKAEA also undertakes cutting edge work with academia, other research organisations and the industrial supply chain in a wide spectrum of areas, including robotics and materials.

More information: Social Media: @UKAEAofficial

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