Tokamak Energy

Tokamak Energy is a privately held fusion-energy and superconducting-technology company based near Oxford in the United Kingdom. Established in 2009 as a commercial spin-out from the United Kingdom Atomic Energy Authority, the company was created to pursue a compact route to fusion power using spherical tokamaks. Its technical strategy combines high-field magnetic confinement, high-temperature superconducting magnets and relatively compact reactor geometries. The company’s experimental programme began with the ST-25 device, which used copper magnets. In 2015, Tokamak Energy upgraded the machine with rare-earth barium copper oxide high-temperature superconductors, creating the ST-25HTS. The use of REBCO-based superconducting technology is central to the company’s approach because stronger magnetic fields can improve plasma confinement and potentially reduce the size and cost of future fusion systems. Tokamak Energy has operated the ST40 high-field compact spherical tokamak since 2018. In March 2022, ST40 achieved a plasma ion temperature above 100 million degrees Celsius, a temperature widely associated with the conditions required for commercially relevant fusion reactions. The result was subsequently discussed in a peer-reviewed scientific publication. The company has also developed magnet technology independently of its reactor programme. In 2019, it reported producing a 24-tesla magnetic field at 20 kelvin with its patented high-temperature superconducting magnet technology. Its magnetics activity has expanded into a broader commercial technology business. Tokamak Energy has identified potential applications for high-temperature superconducting systems in power distribution, life sciences, propulsion and advanced manufacturing, in addition to fusion. In 2023, it announced that a set of HTS magnets had been manufactured for assembly and testing in its Demo4 facility, intended to reproduce conditions relevant to a future fusion power plant. In 2025, Demo4 tests reportedly reproduced fusion-power-plant-relevant magnetic fields, reaching 11.8 tesla at approximately minus 243 degrees Celsius. The company’s development roadmap has included the ST40 and the planned ST80-HTS device, with the longer-term objective of demonstrating commercial fusion electricity in the 2030s. Tokamak Energy has pursued collaborations with national laboratories and government programmes in both the United Kingdom and the United States. Its work with the UK Atomic Energy Authority covers materials, power generation, fuel cycles, diagnostics and remote handling for spherical-tokamak power systems. Its United States subsidiary has participated in the Department of Energy’s milestone-based fusion-development programme. Tokamak Energy has financed its development through a combination of government support and private investment. The company reported cumulative funding of approximately $335 million by 2025, including government and private sources, and announced a $125 million financing round in November 2024. In September 2025, it acquired Ridgway Machines, a Leicestershire engineering business, to expand the manufacturing capacity of its TE Magnetics high-temperature-superconducting business. In 2026, it was named Magnet Systems Partner for the UK Government’s STEP Fusion programme. The company therefore operates across two connected areas: the long-term development of compact fusion power plants and the nearer-term commercialization of advanced superconducting magnet technologies.

Tokamak Energy was established in 2009 as a commercial spin-out from the United Kingdom Atomic Energy Authority in Oxfordshire. It was formed to develop a compact approach to magnetic-confinement fusion based on spherical tokamaks. Unlike conventional large tokamak concepts, a spherical tokamak has a more compact, rounded plasma chamber. Tokamak Energy’s programme has combined this geometry with high-field magnets, particularly high-temperature superconducting magnets, to pursue smaller and potentially more economical fusion systems. One of the company’s early experimental machines was the ST-25, which used copper magnets. In 2015, the device was upgraded with rare-earth barium copper oxide high-temperature superconductors and became known as the ST-25HTS. This transition established high-temperature superconductivity as a major element of the company’s technical strategy. The technology is intended to generate strong magnetic fields while operating at cryogenic temperatures, improving the magnetic confinement of hot plasma and supporting more compact reactor designs. From 2018, Tokamak Energy operated the ST40 high-field compact spherical tokamak. The machine became the company’s principal plasma-development platform. In March 2022, ST40 achieved a plasma ion temperature above 100 million degrees Celsius. That result was presented as an important step toward the temperature regime needed for commercially relevant fusion, and a peer-reviewed paper on the achievement was published through the Institute of Physics. The company’s work has focused not only on temperature but also on the combined engineering problems of plasma confinement, magnets, materials, diagnostics and power extraction. Tokamak Energy developed a separate magnet-technology capability alongside its tokamak programme. In 2019, it announced a 24-tesla magnetic field at 20 kelvin using its patented high-temperature superconducting magnet technology. The company later broadened the intended application of HTS systems beyond fusion to areas including electricity distribution, life sciences, propulsion and advanced manufacturing. This diversification gives the business a potential commercial pathway for magnet products and engineering services while its fusion-reactor programme remains a long-term development effort. In 2023, the company announced that it had built a set of HTS magnets for assembly and testing in Demo4, an in-house facility designed to test magnet assemblies in scenarios relevant to future fusion power plants. In 2025, Tokamak Energy reported that Demo4 had successfully reproduced fusion-power-plant-relevant magnetic fields, reaching 11.8 tesla at approximately minus 243 degrees Celsius. The company has also identified the ST80-HTS as part of its next-stage development roadmap, following the ST40 programme. Government and institutional collaboration has been a recurring feature of the company’s history. In October 2022, Tokamak Energy and the UK Atomic Energy Authority entered a five-year framework agreement concerning spherical tokamaks for power generation. The cooperation covers materials development and testing, power generation, fuel-cycle systems, diagnostics and remote handling, including work relevant to the UK’s STEP fusion machine. In May 2023, the company’s US subsidiary received additional support through the US Department of Energy’s milestone-based fusion-development programme, linking it with American national laboratories, universities and other institutions. Tokamak Energy has financed its development through private investment and public support. By 2025, the company reported cumulative funding of about $335 million, consisting of government and private investment. In November 2024, it announced a $125 million funding round led by East X Ventures and Lingotto Investment Management, with participation from British Patient Capital, Furukawa Electric Company, BW Group and Sabanci Climate Ventures. In December 2024, it announced a partnership involving the US Department of Energy and the UK Department for Energy Security and Net Zero to support a $52 million upgrade to ST40. The company expanded its manufacturing capabilities in September 2025 through the acquisition of Ridgway Machines, a specialist engineering business in Leicestershire. Ridgway became a Tokamak Energy subsidiary while retaining its name, workforce and facility. In 2026, Tokamak Energy was named Magnet Systems Partner for the UK Government’s STEP Fusion programme. Its current identity therefore spans experimental fusion-reactor development and the design, manufacture and application of high-temperature superconducting magnet systems, with the broader aim of contributing to commercial fusion electricity during the 2030s.

• 2026

  Selected as STEP Fusion Magnet Systems Partner

  [1]Tokamak Energyen.wikipedia.org

  Tokamak Energy was named Magnet Systems Partner for the UK Government’s STEP Fusion programme.

• 2025

  Ridgway Machines acquired

  [1]Tokamak Energyen.wikipedia.org

  The acquisition expanded the manufacturing capabilities of Tokamak Energy’s TE Magnetics business.

• 2024

  Major funding round announced

  [1]Tokamak Energyen.wikipedia.org

  Tokamak Energy announced a $125 million investment round led by East X Ventures and Lingotto Investment Management.

• 2023

  Demo4 HTS magnet programme announced

  [1]Tokamak Energyen.wikipedia.org

  The company announced the construction of HTS magnets for testing in its Demo4 facility.

• 2022

  ST40 exceeds 100 million degrees Celsius

  [1]Tokamak Energyen.wikipedia.org

  ST40 reached a plasma ion temperature above 100 million degrees Celsius.

• 2022

  Five-year UKAEA collaboration announced

  [1]Tokamak Energyen.wikipedia.org

  Tokamak Energy and UKAEA agreed to collaborate on spherical-tokamak power-generation technologies.

• 2019

  24-tesla HTS magnet field reported

  [1]Tokamak Energyen.wikipedia.org

  The company announced a 24-tesla magnetic field at 20 kelvin using its patented high-temperature superconducting magnet technology.

• 2018

  ST40 operations begin

  [1]Tokamak Energyen.wikipedia.org

  Tokamak Energy began operating the ST40 high-field compact spherical tokamak.

• 2015

  ST-25 upgraded to ST-25HTS

  [1]Tokamak Energyen.wikipedia.org

  The early copper-magnet ST-25 device was upgraded with REBCO high-temperature superconductors, creating the ST-25HTS.

• 2009

  Company established as a UKAEA commercial spin-out

  [1]Tokamak Energyen.wikipedia.org

  Tokamak Energy was founded near Oxford as a commercial spin-out from the United Kingdom Atomic Energy Authority to develop compact spherical-tokamak fusion systems.

An advanced fusion-energy developer positioned around compact spherical tokamaks, high magnetic fields and commercial high-temperature superconducting technologies.

• Experimental spherical tokamak · 2015

  ST-25HTS

  ST-25HTS is an early Tokamak Energy experimental device created by upgrading the copper-magnet ST-25 with rare-earth barium copper oxide high-temperature superconductors. The machine represents the company’s early transition toward superconducting magnet technology and compact spherical-tokamak research.

• High-field compact spherical tokamak · 2018

  ST40

  ST40 is Tokamak Energy’s high-field compact spherical tokamak and its principal plasma-development platform. Operating since 2018, it was used in the experiments that produced a reported plasma ion temperature above 100 million degrees Celsius in 2022. The facility has also been the subject of a later upgrade programme supported by UK and US government partners.

• Planned high-temperature-superconducting tokamak

  ST80-HTS

  ST80-HTS is part of Tokamak Energy’s development roadmap for a next-generation compact spherical tokamak using high-temperature superconducting magnet technology. Public descriptions identify it as a successor-stage device intended to advance the company toward future fusion-power demonstration, although detailed technical and operational information is limited.

• HTS magnet test facility · 2023

  Demo4

  Demo4 is Tokamak Energy’s in-house facility for assembling and testing high-temperature superconducting magnet systems under conditions relevant to fusion power plants. In 2025, the company reported achieving an 11.8-tesla field at approximately minus 243 degrees Celsius during Demo4 testing.

• High-temperature superconducting magnet business

  TE Magnetics

  TE Magnetics is Tokamak Energy’s superconducting-magnet business. It develops and manufactures high-temperature superconducting magnet systems for fusion and potential non-fusion applications such as power distribution, life sciences, propulsion and advanced manufacturing. The acquisition of Ridgway Machines was intended to strengthen this business’s engineering and manufacturing capacity.

• 2025

  Acquire Ridgway MachinesM&A

  Background

  Tokamak Energy sought to increase the engineering and manufacturing capacity supporting its TE Magnetics business.

  Action taken

  The company acquired Ridgway Machines, a specialist engineering company in Leicestershire, and made it a subsidiary.

  Aftermath

  Ridgway Machines retained its brand, personnel and facility while operating within Tokamak Energy’s group.

  Source

• 2024

  Raise $125 million in private financingOther

  Background

  The company required capital to continue its fusion programme and expand its high-temperature-superconducting magnet business.

  Action taken

  Tokamak Energy announced a $125 million funding round led by East X Ventures and Lingotto Investment Management.

  Aftermath

  The round included investment from British Patient Capital, Furukawa Electric Company, BW Group and Sabanci Climate Ventures.

  Funding raised. $125 million (November 2024 funding round)

  Source

• 2024

  Upgrade the ST40 facilityOther

  Background

  Further ST40 development was intended to accelerate fusion-energy research through government-supported UK-US cooperation.

  Action taken

  Tokamak Energy announced a partnership with the US Department of Energy and the UK Department for Energy Security and Net Zero supporting a $52 million ST40 upgrade.

  Aftermath

  The announcement increased public-sector involvement in the company’s ST40 development programme.

  Planned facility upgrade. $52 million (December 2024 announcement)

  Source

• 2023

  Develop HTS magnet assemblies for Demo4Product launch

  Background

  The company needed to validate high-temperature superconducting magnets in conditions closer to those expected in a future fusion power plant.

  Action taken

  Tokamak Energy built a set of HTS magnets for assembly and testing in its Demo4 facility.

  Aftermath

  The testing programme created an in-house route for validating magnet systems independently of the main tokamak experiments.

  Source

• 2022

  Enter a five-year collaboration with UKAEAStrategy

  Background

  Commercial fusion development requires coordinated work on plasma systems, materials, fuel cycles, diagnostics and remote handling.

  Action taken

  Tokamak Energy and UKAEA established a five-year framework agreement focused on spherical tokamaks for power generation and technologies relevant to the STEP machine.

  Aftermath

  The agreement broadened Tokamak Energy’s institutional collaboration in the UK and connected its spherical-tokamak work with the national STEP programme.

  Source

• 2015

  Convert ST-25 to high-temperature superconducting configurationGeneration change

  Background

  Tokamak Energy sought stronger and more compact magnetic confinement for its spherical-tokamak programme.

  Action taken

  The company upgraded the copper-magnet ST-25 with REBCO high-temperature superconductors and designated the resulting device ST-25HTS.

  Aftermath

  The upgrade established high-temperature superconducting magnets as a central element of the company’s subsequent fusion and magnetics strategy.

  Source

1. 1Tokamak Energyen.wikipedia.org
2. 2Tokamak Energy official websitetokamakenergy.co.uk