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expert reaction to nuclear fusion energy record

Scientists react to the nuclear fusion energy record announced by UKAEA.


Prof Stuart Mangles, Head of the Space, Plasma and Climate Research Community, Imperial College London, said:

“The new results from JET’s final run are very exciting: the ability to control a plasma so that it produces energy for a short but sustained period shows that scientists and engineers are on the way to controlling fusion energy.

“JET has now produced the largest amount of fusion energy to date – nearly 69 megajoules of energy.  By my estimate this is enough energy to make over 600 cups of tea! 

“It will be interesting to see the full technical details of the work as they come out, but perhaps the most important development is the fact that JET has been able to deploy methods to control the plasma to allow this record to be reached.   As fusion machines which produce more power than it takes to run are built, this ability to control the plasma and so prevent damage to the machine will be important. 

“This result really highlights the power of international collaboration, these results wouldn’t have been possible without the work of hundreds of scientists and engineers from across Europe.”


Dr Robbie Scott, Senior Plasma Physicist, Central Laser Facility (CLF), Science and Technology Facilities Council (STFC), said

“The fact they have demonstrated repeated controllability is encouraging for future power plants based on magnetic fusion.

“While the total energy output has been increased, it remains substantially less than that input to the reactions – magnetic fusion is yet to demonstrate fusion ‘energy-gain’, which is critical for power production.  This is contrasted by the recent Laser Fusion results from the National Ignition Facility (NIF) which have demonstrated almost 2 times more energy output than input; NIF is the only experiment to have shown fusion ‘energy-gain’.”


Will Davis, energy expert at the Institution of Engineering and Technology (IET), said

“This is a very significant achievement in the development of fusion energy.

“It shows that a volatile and high-energy plasma can be effectively controlled for a sustained period – and that combining the expertise learned from JET with modern technologies is the way forward to realise commercial fusion energy.  Looking ahead, with modern, high-temperature superconducting magnets used in the future, there should not be a 5 second limitation, because with cryogenic cooling, these magnets can keep running indefinitely.  This is the approach being taken by some private fusion companies and the JET results validate this.

“It is disappointing that JET is at the end of its operational life, but there will be a huge amount of learnings from its decommissioning and disassembling of it – with the expertise gained from the project retained in the UK.

“It’s vital that we keep momentum going, and the MAST-U tokamak (much smaller) at UKAEA will only suffice in the interim.  The Fusion Futures fund will hopefully enable new major fusion energy research projects to be built in the UK as a stepping stone to STEP.”


Dr Mark Wenman (FNucI), Reader in Nuclear Materials, and Co-Director of the Centre for Nuclear Engineering, Imperial College London, said:

“Jet has once again shown what an incredible machine it is and it will be sad to see it being finally decommissioned.  The work at JET clearly proves that conditions most similar to those in future fusion power reactors can be sustained and controlled, burning deuterium-tritium fuel as predicted.  This paves the way for future devices to make sustained fusion a reality.

“Perhaps most importantly they were able to conduct crucial experiments to reduce the heat load on the exhaust and get a stable edge to the plasma, whilst using the deuterium-tritium fuel mix.  These will be critical issues to address for ITER and private fusion companies.

“Jet was however, still limited to just 5 seconds plasma burn, due to its copper coiled magnets, but this will not be the case for ITER and future designs, which will be able to sustain plasma for much longer, due to superconducting magnets, and reach the point of ignition where the plasma can sustain itself.”


Dr Aneeqa Khan, Research Fellow in Nuclear Fusion, University of Manchester, said:

“Nuclear fusion is the process that powers the Sun, where two atoms fuse together, liberating huge amounts of energy. Recreating the conditions in the centre of the Sun on Earth is a huge challenge. We need to heat up isotopes of hydrogen (deuterium and tritium) gas so they become the fourth state of matter, called plasma. In order for the atoms to fuse together on Earth, we need temperatures ten times hotter than the Sun – around 100 million Celsius, and we need a high enough density of the atoms and for a long enough time. The reaction between the deuterium and tritium results in the production of helium and high energy (14 MeV) neutrons.

“These results are really exciting for the fusion community and a great end to the operations of JET which has provided the scientific community with really valuable data over its lifetime, feeding into the designs for new projects. However, to put this in context of commercial fusion there was still no net energy produced.

“This is a great scientific result, but we are still a way off commercial fusion. Building a fusion power plant also has many engineering and materials challenges. However, investment in fusion is growing and we are making real progress. We need to be training up a huge number of people with the skills to work in the field and I hope the technology will be used in the latter half of the century. Global collaboration is key in achieving this.

“Fusion is considered a green source of energy as it does not release carbon dioxide into the atmosphere. If we can make it work it has the potential to provide a stable baseload of electricity to the grid, as well as potential for secondary applications such as hydrogen production or heating. It is not ready yet and therefore it can’t help us with the climate crisis now, however, if progress continues it has the potential to be part of a green energy mix in the latter half of the century and should be part of our long term strategy, while we use other existing technologies such as fission and renewables in the near term.

“Fusion is already too late to deal with the climate crisis, we are already facing the devastation from climate change on a global scale. In the short term we need to use existing low carbon technologies such as fission and renewables, while investing in fusion for the long term, to be part of a diverse low carbon energy mix. We need to be throwing everything we have at the climate crisis. In all these technologies we need to be investing in training people from all over the world so that they can develop the solutions needed to face climate change. It is important to have both short and long term strategies.”



Declared interests

Dr Robbie Scott: “I’m a leading UK laser Fusion researcher and Chair of the UK Inertial Fusion Consortium.”

Dr Mark Wenman: “I don’t have anything to declare.”

Will Davis: no interests to declare.

Aneeqa Khan: I work with UKAEA on projects but I’m not directly funded by them. I have also previously received funding from the SBRI FIP challenge scheme.

No other DOIs received.

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