Commonwealth Fusion Systems
🇺🇸 Devens, US · Founded 2018 · Active
Also known as CFS
Commonwealth Fusion Systems (CFS) is a fusion company founded in 2018 as a spin-off from the Massachusetts Institute of Technology's Plasma Science and Fusion Center, now based in Devens, Massachusetts. It builds tokamaks with high-temperature superconducting magnets, whose stronger fields allow a smaller machine; in September 2021 it tested a large magnet of this kind at 20 tesla. It began building SPARC, a compact deuterium–tritium tokamak meant to produce more fusion power than the heating put into its plasma, in Devens in December 2021; in 2024 it aimed to start SPARC in 2026 and show that gain in 2027. It plans a first power plant, ARC, of about 400 MWe in Chesterfield County, Virginia, in the early 2030s. CFS says it had raised about $4 billion by July 2026; our deals data do not yet hold every round.
- Sector
- Fusion
- Technology
- Tokamak
- Fuel
- Deuterium–tritium
- Role
- Fusion developer
It is the operator of record for SPARC (under construction) and ARC (planned). SPARC carries only planned figures, which are targets rather than results.
Its recorded equity, $3.9bn, is the 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 one award or agreement with no cash figure, which is not added to any total.
Terms
- Tokamak
- Doughnut-shaped magnetic confinement using a strong toroidal field plus a current driven through the plasma itself. The most-studied configuration, and the one ITER uses. Its main open problem is heat exhaust at the divertor, where the plasma edge concentrates power onto a small area, together with the risk of disruptions: sudden, uncontrolled losses of the plasma current.
- Deuterium–tritium
- Lowest ignition threshold; 80% of energy in 14.1 MeV neutrons. The reference fuel for every near-term net-gain claim.
Funding
- 2026-07-30Equity round$1 billion of additional equity financing announced 30 July 2026. The release gives no round name and names no investors ("pension funds, sovereign wealth funds, and infrastructure and industrial corporate partners"). Hyundai Motor Group's investment, announced 10 September 2026, was made as part of this round and is not a separate deal. The release's "total of $4 billion" is the company's cumulative figure and is not a deal.$1bn
- 2025-08-28Equity round · Series BSeries B2 of $863 million announced 28 August 2025. No lead is named. Existing investors named as increasing their stakes include Breakthrough Energy Ventures, Eni and Google; new investors include NVentures (NVIDIA) and a 12-company Japanese consortium that includes Fujikura. Other named investors have no organisation record yet.$863m
- 2023-05Milestone-based awardDOE Milestone-Based Fusion Development ProgramUnpriced
- 2021-12Equity round · Series BSeries B of more than $1.8 billion, announced as closed on 1 December 2021. Led by Tiger Global Management, which has no organisation record yet and so is not linked. The release names more than a dozen other investors; only Eni and Breakthrough Energy Ventures are linked here, so the participant list is partial.$1.8bn
- 2020-05Equity roundEquity offering reported on SEC Form D: $80,600,007 sold of a $100,000,004 offering at the time of filing (26 May 2020), first sale 11 May 2020. The Form D does not name the round, so no round label is recorded. The amount is a minimum because $19.4 million remained unsold when the notice was filed.$81m
- 2018-05Equity roundEquity offering reported on SEC Form D/A: $114,999,971 sold, first sale 30 May 2018, offering fully sold. The Form D does not name the round, so no round label is recorded.$115m
Results
Plasma gain (Qplasma)
Fusion power produced ÷ External heating power coupled into the plasma
planned
SPARC: Proving commercial fusion energy is possible | Commonwealth Fusion Systems
Fusion triple product (nTτE)
planned
Continuing progress toward fusion energy breakeven and gain as measured against the Lawson criteria
Ion temperature (peak)
planned
Continuing progress toward fusion energy breakeven and gain as measured against the Lawson criteria
Plasma density
planned
Continuing progress toward fusion energy breakeven and gain as measured against the Lawson criteria
Energy confinement time (τE)
planned
Continuing progress toward fusion energy breakeven and gain as measured against the Lawson criteria
Design values
| Device | Parameter | Value | Unit | Status |
|---|---|---|---|---|
| ARC | Net electrical capacity (design) | 400 | MW | design valueplanned |
| SPARC | Major radius | 1.85 | m | design valueplanned |
| SPARC | Minor radius | 0.57 | m | design valueplanned |
| SPARC | On-axis magnetic field | 12.2 | T | design valueplanned |
| SPARC | Plasma current | 8.7 | MA | design valueplanned |
Devices
Related companies
- Maritime Fusion
- Energy Singularity
- Firefly Fusion
- General Atomics
- Institute of Plasma Physics, Chinese Academy of Sciences
- ITER Organization
- Korea Institute of Fusion Energy
- Max Planck Institute for Plasma Physics
- MIT Plasma Science and Fusion Center
- National Nuclear Center of the Republic of Kazakhstan
- Pranos Fusion
- UK Atomic Energy Authority
Sources
- Home | Commonwealth Fusion Systemsoperator
- Commonwealth Fusion Systemsaggregator
- CFS news and mediaoperator
- Technology | Commonwealth Fusion Systemsoperator