Nuclear Fusion

Commonwealth Fusion Systems

Private

Commonwealth Fusion Systems is building commercial fusion systems around high-temperature superconducting magnet technology developed with MIT. SPARC, its fusion-energy demonstration tokamak under construction in Devens, Massachusetts, was about 80% complete as of late July 2026: the first of 18 toroidal-field magnets was installed in January, and a company LinkedIn post on September 22, 2026 said eight of 18 TF magnets are now installed, up from three publicly confirmed in late June. That eight-magnet count is a company social-media figure, not an independent inspection; no later official CFS blog or photo essay opened for this patch restated the eight-magnet figure or dated the dry dress rehearsal after the September 16, 2026 8 K cryogenic run, which still described DDR as upcoming. The remaining ten TF magnets now sit on the 2027 first-plasma and Q>1 path after the end-of-summer all-18 target was missed. ARC, CFS' first commercial plant - officially named the Fall Line Fusion Power Station and sited on 100 acres in Chesterfield County, Virginia - became in April 2026 the first fusion project to file for grid interconnection with PJM, and on June 4, 2026 CFS published a five-paper ARC Physics Basis in the Journal of Plasma Physics projecting ~1.1 GW of fusion power and ~400 MW of net electricity. On September 30, 2026 CFS ordered more than 10,000 km (3 GA-m) of HTS tape from Fujikura for ARC plants starting at Fall Line; neither company disclosed contract value, annual volume, first-shipment date, or tape kilometres per ARC machine. Sorbom told Khaleej Times deliveries could begin in one to two years, manufacturing remains at Fujikura's Japan factory, and SPARC contains about 1.5 GA-m, roughly half the new order. Fujikura's Japanese PR restates the 10,000 km-plus volume and capacity-expansion investment but adds no Japan-site capacity in km per year. CFS has also begun monetizing its HTS magnet platform, signing a potentially multi-billion-dollar long-term magnet supply deal with Realta Fusion and launching a SPARC digital twin program with Nvidia and Siemens, and in July 2026 became the first international partner in the UK Atomic Energy Authority's 220 million pound LIBRTI tritium-breeding program. On July 30, 2026 CFS closed $1B more from pension and sovereign-wealth funds (bringing total capital to $4B) and named former Moderna CFO Lorence Kim as chief financial officer.

2018 · 🇺🇸 Devens, Massachusetts

Helion Energy

Private

Helion Energy is building fusion generators aimed at producing commercial electricity from fusion. Its Polaris prototype began operating in late 2024 and in February 2026 became the first privately developed fusion machine to demonstrate measurable deuterium-tritium fusion at 150 million degrees Celsius. Helion is now advancing Orion in Malaga, Washington, where site work began in 2025 and generator-building construction is underway after Washington State issued the world's first fusion-plant licenses in June 2026. The company's own Orion page now says the plant is designed to meet the 2023 Microsoft PPA for at least 50 MW, with initial operations beginning in 2028; public-affairs director Jackie Siebens said at FusionX that Helion will not have 50 MW at full operation in 2028 and that the Microsoft contract requires Orion to be connected to the grid and begin operations by the end of 2028, with full power not expected before 2029 or 2030. A smaller Tiny Merge testbed is still being integrated at Everett after an August 28, 2026 first vacuum pump-down; the end-of-summer 2026 online target was not met. On September 8, 2026 Helion opened a downtown Seattle office for its business team and CEO David Kirtley said headcount has grown to 800. Helion's Series G, initially closed at $465M on June 4, 2026, was later marked oversubscribed and closed at $500M in September 2026, still at a $15.5B post-money valuation led by Thrive Capital, lifting total funding to more than $1.5B. OpenAI remains in unsigned, advanced talks to buy fusion power from Helion at gigawatt scale as of September 16, 2026, a negotiation that prompted Sam Altman to step down as Helion board chair on March 23, 2026.

2013 · 🇺🇸 Everett, Washington

Pacific Fusion

Private

Pacific Fusion is taking the inertial route to fusion rather than the magnetic one: instead of holding plasma in a magnetic bottle, it crushes a small capsule of deuterium-tritium fuel with an enormous, extremely fast electrical pulse. The company's distinguishing technology is the impedance-matched Marx generator, a pulser architecture that is simpler and cheaper than the systems used at national laboratories, and its plan is to gang 156 production-scale pulser modules into a Demonstration System designed to reach net facility gain - more fusion energy out than the total energy stored in the machine - by 2030. Founded in 2023 by Eric Lander, Keith LeChien, Will Regan, Carrie von Muench and Leland Ellison, it launched publicly in October 2024 with a roughly $900M Series A led by General Catalyst that is released in tranches against technical milestones; the round has since passed $1B as those milestones cleared. In June 2026 a scaled module prototype delivered more than 440 gigawatts at about 1.1 megavolts in an 80-nanosecond pulse, and in July 2026 the Sirius prototype at Lawrence Livermore National Laboratory passed 3,000 full-power shots at 95% energy efficiency. Pacific Fusion broke ground on its $1B, roughly 225,000-square-foot research and manufacturing campus at Mesa del Sol in Albuquerque, New Mexico, on August 25, 2026 - the National Nuclear Security Administration signed a fusion-research MOU with the company the same day - and Nature reporters visiting the nearby Los Lunas build center that month found two of the more than 150 full-scale pulser modules the Demonstration System needs already completed. The Users Program FAQ, still current as of September 2026, says Demonstration System commissioning is expected to begin in 2028, with the first external-user campaigns in 2029 after a 2027 call for proposals. The machine is designed to produce more than 100 megajoules of fusion output per pulse, about 10 times NIF's record output.

2023 · 🇺🇸 Fremont, California

Proxima Fusion

Private

Proxima Fusion is Europe's best-funded fusion company and the first research spin-off from the Max Planck Institute for Plasma Physics, founded in Munich in 2023 to commercialize the stellarator - a twisted magnetic bottle that is harder to build than a tokamak but runs continuously without needing to drive a current through the plasma. Its quasi-isodynamic design, Stellaris, was published in February 2025 as the first peer-reviewed, fully integrated stellarator power plant concept. In February 2026 Proxima signed a memorandum of understanding with RWE, the Free State of Bavaria and the Max Planck IPP to build Alpha, a roughly €2B net-energy demonstrator at Garching near Munich targeted to begin operating in 2031, followed by a commercial Stellaris plant at the decommissioned Gundremmingen nuclear site later in the 2030s; an Alpha Alliance of more than 50 European industrial companies including Siemens Energy, Framatome, Air Liquide and Thales now backs the project (up from 30+ at the February 2026 launch). On July 7, 2026 the company raised €411M ($468M) at a €2.4B ($2.7B) valuation, led by XTX Ventures and East X Ventures with RWE and Google as strategic investors, taking total funding past €650M and funding completion of its Stellarator Model Coil in late 2027. On September 9, 2026 Proxima signed an MoU with the State of Lower Saxony to lay foundations for Europe's first large-scale fusion-grade HTS tape plant: about €140M for the first two phases through end-2029, split equally public/private, with Lower Saxony contributing €21M. Proxima would be the anchor customer for about 20,000 km of tape for Alpha and 40,000 km for Stellaris; no site has been named.

2023 · 🇩🇪 Munich, Germany

TAE Technologies

Private (proposed TMTG merger; targeted Q4 2026 close)

TAE Technologies is a private fusion company developing hydrogen-boron fusion with a beam-driven field-reversed-configuration architecture. Its 2025 'Norm' breakthrough reduced reactor complexity enough to skip the planned Copernicus step and move directly toward Da Vinci, its first prototype power plant. On August 6, 2026 TAE said Da Vinci had completed its key designs, with construction still planned later in 2026 and first fusion power targeted in 2031. In 2026 it also completed a multi-state site evaluation tour for the first 50 MWe plant (Alabama, Ohio, Texas), formally established the TAE Beam UK joint venture with UKAEA at Culham, and is targeting a Q4 2026 close of its $6B all-stock merger with Trump Media & Technology Group. Form S-4 file 333-299201 was accepted 30 September 2026 and is not effective; TMTG filed a Rule 473 delaying amendment on 2 October 2026. The extra $100 million second tranche is requestable through 29 November 2026, but no EDGAR 8-K reports a drawdown request or funding. No final plant site has been announced. The merger agreement's outside date is December 18, 2026. The company now states more than $1.5B in private capital. On September 9, 2026 it named Darrell Taylor General Counsel. TAE Power Solutions and TAE Life Sciences commercialize adjacent power-delivery and oncology technologies derived from its fusion R&D.

1998 · 🇺🇸 Foothill Ranch, California

Tokamak Energy

Private

Tokamak Energy is a UK fusion and high-temperature superconducting (HTS) company spun out of the UK Atomic Energy Authority in 2009. It now describes itself first as a commercial superconducting and fusion-technologies supplier rather than the builder of its own power plant: the August 2026 Nuclear Fusion Focus Collection published the ST-E1 pilot-plant design, and the company said it will not go on to construct that plant or future pilot plants itself. Its operating machine is ST40, which reached 100 million degrees Celsius in 2022 and closed out 2025 with three records (1 MA plasma current, highest stored energy, triple product up over 30% to about 8 x 10^18 m^-3 keV s) before entering a $52M DOE/DESNZ upgrade that still runs through most of 2026. On September 9, 2026 Tokamak Energy completed a 14-month Demo4 campaign, pushing the 44-coil HTS magnet system to a peak field of 13.7 tesla (up from the November 2025 11.8 T system-level result), 5,600 amps in the toroidal-field coils, 150 MPa transverse stress, and roughly 10,000 operating hours, with results presented at the Applied Superconductivity Conference in Pittsburgh. In April 2026 Tokamak Energy was named Magnet Systems Partner for the UK government's STEP prototype under a £70M contract to March 2029. TE Magnetics sells that capability commercially (Ridgway Machines acquired in 2025; a 2025 General Atomics/DARPA undersea-propulsion magnet contract; an April 2026 data-center HTS power-distribution study), and the company also supports the FAST superconducting-tokamak project in Japan.

2009 · 🇬🇧 Milton Park, Oxfordshire, United Kingdom