Tokamak Energy
🇬🇧 GB · Founded 2009 · Active
Tokamak Energy is a private company in Oxfordshire, spun out of the UK Atomic Energy Authority in 2009. It builds spherical tokamaks, a compact form of the tokamak, and its ST40 device, operating since 2018, reached a plasma ion temperature above 100 million degrees Celsius in March 2022. ST40 is being upgraded in a $52 million programme with the US Department of Energy and the UK Department for Energy Security and Net Zero. Through its TE Magnetics division it develops high-temperature superconducting magnets; its Demo4 magnet system reached 11.8 tesla in 2025. It is magnet systems partner for the UK's STEP prototype plant under a £70 million contract running to 2029, and had raised about $335 million by 2025.
- Sector
- Fusion, Supply chain
- Technology
- Spherical tokamak
- Fuel
- Deuterium–tritium
- Role
- Fusion developer, Supplier
It is the operator of record for ST40 (operating). Measured results for ST40 are listed below.
Its recorded equity, $125m, is the 17th largest of the 25 organisations with a priced round here. Not every round is on record, so this is not its total raised.
It also holds 2 awards or agreements with no cash figure, which are not added to any total.
Terms
- Spherical tokamak
- A tokamak squeezed towards a cored-apple shape. The tighter aspect ratio holds plasma pressure with less magnetic field, which is efficient, but leaves very little room at the centre for the central column.
- Deuterium–tritium
- Lowest ignition threshold; 80% of energy in 14.1 MeV neutrons. The reference fuel for every near-term net-gain claim.
Funding
- 2024-12-05GrantPublic co-funding of a $52 million ST40 upgrade programme announced 5 December 2024 with the US DOE and the UK Department for Energy Security and Net Zero (DESNZ). The company says the $52 million "is divided evenly among all three partners", so Tokamak Energy funds a third itself. The two public contributions are to a joint programme, not stated as cash to the company, and their form (grant, cost share or in-kind) is not stated. No amount is recorded.Unpriced
- 2024-11Equity round · Growth$125 million announced 20 November 2024, co-led by East X Ventures and Lingotto Investment Management (neither has an organisation record yet). The release's "$335 million raised since 2009" mixes $275 million private with $60 million UK and US public funding and is not a deal.$125m
- 2023-05Milestone-based awardDOE Milestone-Based Fusion Development ProgramUnpriced
Results
Ion temperature (peak)
achieved2022shot 10009
Fusion triple product (nTτE)
claimed2022shot 10009
Continuing progress toward fusion energy breakeven and gain as measured against the Lawson criteria
Plasma density
claimed2022shot 10009
Continuing progress toward fusion energy breakeven and gain as measured against the Lawson criteria
Energy confinement time (τE)
claimed2022shot 10009
Continuing progress toward fusion energy breakeven and gain as measured against the Lawson criteria
Ion temperature (peak)
superseded2022shot 10009
Fusion triple product (nTτE)
claimed2025
Knockout results from Tokamak Energy’s record-breaking ST40 ends 2025 on a high
Plasma current (peak)
claimed2025
Knockout results from Tokamak Energy’s record-breaking ST40 ends 2025 on a high
Fusion triple product (nTτE) (peak)
claimed2022
Design values
| Device | Parameter | Value | Unit | Status |
|---|---|---|---|---|
| ST40 | Major radius | 0.5 | m | design valueclaimed |
| ST40 | Minor radius | 0.3 | m | design valueclaimed |
| ST40 | On-axis magnetic field | 3 | T | design valueclaimed |
| ST40 | Plasma current | 2 | MA | design valueclaimed |
| ST40 | Plasma duration (nominal) | 1 | s | design valueclaimed |
Devices
People
- Dr Chris MartinChairman
- Warrick MatthewsChief Executive Officer
- David Gray CBENon-Executive Director
- Sir Warren East CBENon-Executive Director
- Daniel FreemanNon-Executive Director
- Erik BoninoNon-Executive Director
- Martin KleppeNon-Executive Director
- Itxaso ArizaChief Technology Officer
- Christian LowisGeneral Counsel and Company Secretary
- Dr Liam BrennanManaging Director, TE Magnetics
- Dr Michael GinsbergPresident, Tokamak Energy Inc.
- Dr Ross MorganPresident, Tokamak Energy K.K.; Managing Director of Fusion
- Dr Mike PortonCompany Chief Engineer
- Jane ShannonDirector of People & Engagement
- Dr David KinghamFounder and Senior Advisor · founder
- Dr Mikhail GryaznevichCo-founder · founder