The archive · Climate & Energy · Technical decision · 2018–2026
CFS installs first SPARC magnet, betting HTS magnets prove fusion Q>1
CFS, MIT spinout, bets HTS magnets shrink tokamaks; installed first SPARC magnet in 2026-01, aims first plasma 2027, raised $3B, grid by early 2030s.
Commonwealth Fusion Systems
What the business is
CFS makes fusion power plants: first build the SPARC demonstration machine to verify that magnetically confined fusion can generate electricity, then build ARC (400MW, near Richmond, Virginia), which it claims will be the world's first stable grid-connected fusion power plant.
Starting capital：Cumulative funding of about $3B, including the $863M Series B2 in 2025-08, participated in by about 30 investors including Nvidia and Google
How it started
In 2018, Commonwealth Fusion Systems (CFS) was spun off from the MIT Plasma Science and Fusion Center (MIT 等离子体科学与聚变中心) and founded by Bob Mumgaard and others, betting on high-temperature superconducting (REBCO) magnets: with stronger magnetic fields, a tokamak can be much smaller than ITER and much lower in construction cost. The company first built the SPARC demonstration machine outside Boston, with the goal of first proving scientific feasibility, then scaling it up into a commercial power plant.
What happened
In 2025-03, the 24-foot-wide, 75-ton stainless steel cryostat for SPARC was put in place; on 2026-01-06, at CES, CFS announced that it had installed the first of 18 24-ton D-shaped high-temperature superconducting magnets (capable of producing 20 tesla, about 13 times the magnetic field of a conventional MRI, cooled to -253°C and carrying 30,000 amps of current). CEO Bob Mumgaard said all 18 magnets would be installed by late summer that year, the reactor would be largely complete by year-end, and first plasma would occur in 2027. In the same period, CFS announced collaborations with Nvidia (Omniverse digital twin) and Siemens (design and manufacturing software), and disclosed cumulative funding of about $3B.
How it ended up
Still on the way: as of 2026-09-01, SPARC is still under assembly, with first plasma expected in 2027; the first commercial power plant ARC (400MW, enough for about 300,000 households) is planned to connect to the grid in the early 2030s outside Richmond, Virginia, and if successful would be the world's first fusion power plant stably supplying electricity to the grid.
Background
Commonwealth Fusion Systems (CFS) makes fusion power plants: spun off from the MIT Plasma Science and Fusion Center (MIT 等离子体科学与聚变中心) in 2018, betting that high-temperature superconducting magnets can build a tokamak much smaller than ITER but stronger. The company first built the SPARC demonstration machine outside Boston to prove that fusion can produce more energy than it consumes (Q>1), then scale it up into the 400MW commercial power plant ARC.
In 2025-03, SPARC's 75-ton stainless steel cryostat was put in place; on 2026-01-06 at CES, CFS announced it had installed the first of 18 D-shaped high-temperature superconducting magnets. Each magnet weighs 24 tons, can produce a 20-tesla magnetic field (about 13 times that of a conventional MRI), and after being cooled to -253°C carries 30,000 amps of current, heating the plasma to above 100 million degrees. CEO Bob Mumgaard said all 18 magnets would be installed by late summer that year, the reactor would be largely complete by year-end, and first plasma would occur in 2027.
To remove risk before real-machine ignition, CFS is collaborating with Nvidia (Omniverse digital twin) and Siemens (design and manufacturing software), using virtual models and physical machines to learn in parallel. Funding: the company has raised about $3B cumulatively, including the $863M Series B2 in 2025-08, in which about 30 investors including Nvidia and Google participated.
As of 2026-09-01, SPARC is still under assembly and has not ignited; if the demonstration succeeds, the first commercial power plant ARC is planned to connect to the grid in the early 2030s outside Richmond, Virginia, at which point it would be the world's first fusion power plant stably supplying electricity to the grid. The endgame of this bet has not yet arrived.
What has to be true
- HTS magnets are linchpin; if weak, company fails. So manufacture in-house, then assemble machine.
- SPARC only tests electricity; commercial risk deferred to ARC. Milestones match funding pace.
- Digital twins with Nvidia/Siemens learn with physical machine, compressing validation.
- $3B bet on early 2030s grid, counting on AI data center power demand.
What can be applied
Break fusion into verifiable milestones: prove magnets, then electricity. Use digital twins to cut risk and cost. This playbook moves deep tech from lab to plant.
Aftermath
As of 2026-09-01: SPARC assembly is proceeding on plan, with 18 magnets expected to be installed by late summer 2026 and the reactor largely complete by year-end, first plasma in 2027; ARC (400MW) is sited near Richmond, Virginia, targeting becoming the world's first stably grid-connected fusion power plant in the early 2030s; the company has raised about $3B cumulatively and is building digital twins with Nvidia and Siemens. Fusion has not yet produced electricity, and the bet is not over.
Sources
- Commonwealth Fusion Systems installs reactor magnet, lands deal with Nvidia
- Fusion power nearly ready for prime time as Commonwealth builds first pilot for limitless, clean energy with AI help from Siemens, Nvidia
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