Tokamak Energy
UK compact spherical tokamak with HTS magnets. First private machine to reach 100M C plasma temperature
Milton Park, Oxfordshire, UK~250Founded 2009~$320M+ (private) + UK government grants raisedUndisclosed valuationwww.tokamakenergy.com
SectorsNuclear
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
Revenue path beyond fusion itself; magnets sold to MRI / particle-accelerator markets
Funding History
Total raised: ~$320M+ (private) + UK government grants · 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 |
Product Specifications
| 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 |
Partnerships & Investors
UK Atomic Energy Authority (Culham)Strategic / Origin
Tokamak Energy spun out of UK national fusion program; co-located at Culham; deep technical collaboration.
British Patient CapitalUK Government / Investor
UK sovereign deep-tech fund; cornerstone of UK fusion-sovereignty thesis.
Legal & GeneralInvestor
UK pension giant; one of the few mainstream UK financial-services backers of fusion.
L1 Group (Mikhail Fridman / Petr Aven)Long-term Investor
Cornerstone European investor across multiple rounds.
US Department of EnergyResearch
Recipient of US DOE INFUSE program grants; transatlantic fusion R&D collaboration.
Princeton Plasma Physics Lab + Oak RidgeResearch
US national-lab co-development on spherical-tokamak physics + HTS magnet engineering.
Key Milestones
2009
Company Founded
Alan Sykes, Mikhail Gryaznevich, David Kingham spin Tokamak Energy out of UK Culham Centre for Fusion Energy
2017
ST40 First Plasma
Fourth-generation spherical tokamak commissioned at Milton Park
Jun 2018
Series B at $20M
Legal & General leads; mainstream UK-pension capital backs fusion
Mar 2022
100M C Plasma Milestone
ST40 reaches 100M C plasma temperature; first privately funded fusion machine to cross this threshold (above sun-core temperature)
2023
Demo4 Design Concept
Pilot plant concept based on ST-HTS architecture; target net electricity in 2030s
Mar 2024
ST80-HTS Construction Decision
Next-gen 80% scale machine commissioned for build; first all-HTS spherical tokamak design
2025
HTS Magnet Demonstrator
Tokamak Energy's HTS magnet program delivers full-scale prototypes; technology now sold as a standalone product line
2030s (target)
Net-Electricity Pilot
Demo4 pilot plant target; UK industrial-strategy aligned timeline