Hotter than the centre of the Sun: UK prototype reaches 15 million degreesOur news
6 June 2018

Hotter than the centre of the Sun: UK prototype reaches 15 million degrees

  • UK company reaches key milestone in plan to deliver clean energy through fusion power
  • ST40 device progressing towards temperatures required for fusion energy

Tokamak Energy, one of the world’s leading private fusion energy ventures, today announces that it has achieved plasma temperatures of over 15 million degrees Celsius, hotter than the centre of the Sun.

The ‘ST40’ device in which this was achieved was built by Tokamak Energy and commissioned in 2017.  It is the third machine in a five-stage plan to achieve abundant, clean fusion energy. The company plans to produce industrial scale energy by 2025.

The Tokamak Energy approach is based on well-established science and is advancing rapidly. The next target for the Tokamak Energy team is to push on to achieve the temperatures necessary for controlled fusion on Earth.

Tokamak Energy grew out of the Culham Centre for Fusion Energy in Oxfordshire. A key innovation is that the company combines spherical tokamaks with the latest generation of high temperature superconducting magnets (HTS).

Jonathan Carling, CEO at Tokamak Energy:

“We are taking significant steps towards achieving fusion energy and doing so with the agility of a private venture, driven by the goal of achieving something that will have huge benefits worldwide.

“Reaching 15 million degrees is yet another indicator of the progress at Tokamak Energy and a further validation of our approach. Our aim is to make fusion energy a commercial reality by 2030. We view the journey as a series of engineering challenges, raising additional investment on reaching each new milestone.”

Dr David Kingham, Co-founder of Tokamak Energy, commented:

“The world needs abundant, controllable, clean energy.  Our business plan is built on strong scientific foundations and this milestone is a significant step in our compact spherical tokamak route to fusion power.

“Fusion is a major challenge, but one that must be tackled. We believe that with collaboration, dedication and investment, fusion will be an important part of achieving deep decarbonisation of the global energy supply in the 2030s and beyond.”


– Ends –

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Notes for editors:

  1. About Tokamak Energy

Tokamak Energy is a private company working to develop compact fusion power. The firm is led by experienced management and employs a team of magnet engineers and fusion experts from globally renowned public and private institutions.

Tokamak Energy grew out from Culham Laboratory, which is the world’s leading center for magnetic fusion energy research and home to the world’s most powerful tokamak, JET, which produced 16MW of fusion power in 1997. Tokamak Energy is focused on spherical tokamaks, pioneered at Culham, because these compact devices can achieve a much higher plasma pressure for a given magnetic field than conventional tokamaks, i.e. they are more efficient.

Enhancing this design, Tokamak Energy is deploying high temperature superconducting magnets to control the plasma within its devices. These allow high magnetic fields to be created in the confined dimensions of compact tokamaks, further improving the efficiency of the device.

Tokamak Energy is following a five-stage plan towards producing fusion power:

  • Stage 1: Build a small prototype tokamak to demonstrate the concept (the ST25) – achieved 2013.
  • Stage 2: Build a tokamak with exclusively high temperature superconducting (HTS) magnets (the ST25 HTS) – achieved 2015.
  • Stage 3: Reach fusion temperatures of 100 million degrees in a compact tokamak (the ST40), followed by further development of the ST40 to produce high density plasmas and to approach fusion energy gain conditions.
  • Stage 4: Achieve industrial scale energy with the ‘Fusion Power Demonstrator’ by 2025.
  • Stage 5: Produce commercially viable fusion power with the first ‘Fusion Power Module’ by 2030.

In 2017, Tokamak Energy was selected by the International Energy Agency (IEA) as one of three leading innovative ideas in fusion. It was the only UK representative invited to speak at the IEA’s meeting on developing fusion power, and Tokamak Energy’s Co-Founder Dr David Kingham presented the company’s plans.

Tokamak Energy has raised private investment of over £30 million to date, with investors including Oxford Instruments, Legal & General Capital and the Institution of Mechanical Engineers.

Tokamak Energy has an eminent Scientific Advisory Board chaired by Lord Julian Hunt FRS. Members include Professor Jack Connor FRS (one of the most influential theoretical plasma physicists in fusion), Professor George Smith FRS (emeritus professor of materials at the University of Oxford), Professor Bill Lee FREng (ex Director of the Centre for Nuclear Engineering at Imperial College London) and Professor Colin Windsor FRS (a neutronics and neural networks specialist).

Tokamak Energy has science and engineering offices at Culham and Milton Park, Oxfordshire and a new tokamak engineering facility and superconducting magnet development laboratory at Milton Park.


  1. About fusion

Fusion is the reaction that powers the stars. Energy is released when two small particles come together and fuse into one larger particle.  In experiments on Earth, these small particles are the nuclei of deuterium and tritium – types of heavy hydrogen – and they fuse together to make a helium nucleus.  The waste product of fusion is helium, which is safe.  Fusion produces no greenhouse gases and no long-lived radioactive waste yet it produces vast amounts of energy from very little fuel. The lithium from a laptop battery combined with the deuterium in half a bath of water could supply as much energy at 70 tonnes of coal.  As such it offers a clean, green and plentiful energy solution for thousands of years into the future if it can be harnessed on Earth.

For fusion reactions to happen the deuterium and tritium must be very hot, so that the particles are moving so fast that if they collide they will overcome the mutual repulsion they feel for each other and get close enough to fuse. At JET, the world’s largest operating tokamak, which once produced 16MW of fusion power, the fuel is heated to more than 100 million degrees – 7 times hotter than the center of the Sun!  Tokamak Energy, based just 5 miles away from JET, now aims to achieve this temperature in much smaller, lower cost tokamaks.

Magnetic fields are used to keep the superheated fuel (now an electrically charged gas called plasma) from touching the walls of its container and so keep it hot enough for fusion to occur.  If the plasma does hit the wall it is not dangerous, it just cools down and everything stops.  The specialized machines used by Tokamak Energy and others for fusion are called ‘tokamaks’.


  1. About tokamaks

‘Tokamak’ is a Russian acronym that stands for toroidal chamber magnetic coils, which concisely describes the machine – a toroidal (doughnut-shaped) vessel with magnetic coils to trap and control the plasma.  When they were introduced in the 1960s, tokamaks showed dramatically improved performance over the other methods being investigated. They heated and trapped the fuel much better than other approaches. Tokamaks were rapidly adopted by many international research teams and have remained the front runners in fusion research ever since.


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