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Tokamak EnergyUK compact spherical tokamak with HTS magnets. First private machine to reach 100M C plasma temperature
ST40 Plasma Temperature
100M C (Mar 2022)
First privately funded fusion machine to reach 100M C (above sun-core temperature)
Approach
Compact spherical tokamak + HTS magnets
Spherical aspect ratio improves plasma stability; HTS magnets enable compact footprint
UK Government Position
Anchor of UK fusion sovereignty
British Patient Capital backing + Culham co-location; aligned with UK STEP pilot-plant program
Commercial Magnet Product Line
HTS magnets sold standalone
£70M UK Fusion Energy contract through Mar 2029; magnets also sold to MRI / accelerator markets
Total raised: ~$340M+ (private) + UK government grants and contracts · Latest valuation: Undisclosed
| Round | Date | Amount | Valuation | Key Investors |
|---|---|---|---|---|
| Founding / Early | 2009-2018 | Undisclosed | - | Oxford Instruments (spinout origin)Legal & GeneralL1 Group |
| Series B | Jul 2018 | $20M | - | Legal & GeneralL1 Group |
| Series C | Mar 2022 | $50M | - | L1 GroupLegal & General |
| Strategic | Mar 2024 | $52M | - | L1 GroupBritish Patient CapitalUK government cost-share matching |
| Strategic | Nov 2024 | $125M | - | Lingotto (lead)East X Venturesexisting investors |
| System | Type | Status |
|---|---|---|
| ST40 | Fourth-generation spherical tokamak (100M C plasma achieved Mar 2022) | Operating since 2017 |
| ST80-HTS | Next-generation 80% scale spherical tokamak with HTS magnets | Under construction |
| Demo4 | Pilot plant concept (net electricity target) | Concept design |
| HTS Magnet Systems | High-temperature superconducting magnets sold as standalone product line | Commercial |
Tokamak Energy spun out of UK national fusion program; co-located at Culham; deep technical collaboration.
UK sovereign deep-tech fund; cornerstone of UK fusion-sovereignty thesis.
UK pension giant; one of the few mainstream UK financial-services backers of fusion.
Cornerstone European investor across multiple rounds.
Recipient of US DOE INFUSE program grants; transatlantic fusion R&D collaboration.
US national-lab co-development on spherical-tokamak physics + HTS magnet engineering.
Alan Sykes, Mikhail Gryaznevich, David Kingham spin Tokamak Energy out of UK Culham Centre for Fusion Energy
Fourth-generation spherical tokamak commissioned at Milton Park
Legal & General leads; mainstream UK-pension capital backs fusion
ST40 reaches 100M C plasma temperature; first privately funded fusion machine to cross this threshold (above sun-core temperature)
Pilot plant concept based on ST-HTS architecture; target net electricity in 2030s
Next-gen 80% scale machine commissioned for build; first all-HTS spherical tokamak design
Tokamak Energy's HTS magnet program delivers full-scale prototypes; technology now sold as a standalone product line
Demo4 pilot plant target; UK industrial-strategy aligned timeline
UK developer of a compact spherical tokamak using HTS magnets. ST40 machine achieved 100 million degree Celsius plasma in March 2022. ST80-HTS next-generation machine in development. Tokamak Energy was founded in 2009, is headquartered in Milton Park, Oxfordshire, UK and employs ~250.
Tokamak Energy has raised ~$340M+ (private) + UK government grants and contracts in total at a Undisclosed valuation, based on the funding rounds Sterling tracks.
Sterling groups Tokamak Energy in the Nuclear sector, alongside Commonwealth Fusion Systems (private), Helion Energy (private), TAE Technologies (private), Pacific Fusion (private) and General Fusion (private).
If you are researching Tokamak Energy, also look at Commonwealth Fusion Systems (private), Helion Energy (private) and TAE Technologies (private). You can browse the full Nuclear sector on Sterling.
