Private Fusion Hits Three Firsts in 2026 as ITER's $22B Bet Runs Late

Three private fusion companies reported hard technical and financial milestones between February and July 2026, according to their own announcements. None of them has produced net electricity. The largest publicly funded fusion project on earth, ITER, is years behind its original schedule.

The most striking claim comes from Helion, based in Everett, Washington. In a newsroom post dated 13 February 2026, the company said its seventh-generation Polaris prototype became the first privately developed fusion machine to demonstrate measurable deuterium-tritium fusion. It reached plasma temperatures of 150 million degrees Celsius. Polaris began operating at the end of 2024.

What Helion actually demonstrated

Deuterium-tritium is the easiest fuel mix to burn. It is also the one that produces copious neutrons, which is why most fusion machines that use it are built behind thick shielding. Helion's own announcement frames D-T as a stepping stone rather than the destination.

"Achieving thermonuclear fusion using deuterium-tritium fuel is one step in Polaris' testing program," the company writes. Helion says it will keep raising temperatures in Polaris to reach conditions for deuterium-helium-3 fusion, the fuel it intends to use in commercial operations. The 150 million degree figure breaks Helion's own earlier record of 100 million degrees, set by its sixth-generation Trenta prototype. Within the industry, 100 million degrees is treated as the threshold for a commercially relevant machine.

"It is exciting to see evidence of D-T fusion and temperatures exceeding 13 keV or 150 million degrees Celsius, and I look forward to seeing more progress."

That assessment comes from Ryan McBride, an inertial confinement fusion and pulsed power specialist who has worked as a department manager at Sandia National Laboratories and as a professor of nuclear engineering, electrical engineering and applied physics at the University of Michigan. Helion also quotes Jean Paul Allain, associate director for fusion energy sciences in the Department of Energy's Office of Science. Allain said the Polaris data indicates "strong progress" and that getting fusion on the grid requires approaches that allow rapid turnaround in design and testing.

Note what is missing. Helion has not published a scientific gain figure, that is, the ratio of fusion power produced to heating power delivered to the plasma. It has not claimed net energy. The company says it received the first regulatory approval to possess and use tritium for demonstrating fusion energy production. That is a licensing fact rather than a physics result.

Helion is not only running a physics program. In July 2025 it began construction on the site of Orion, its first commercial machine, in Malaga, Washington. The company says Orion will deliver electricity from fusion to the grid for Microsoft. That is a customer commitment made before the underlying performance data has been shown publicly.

Realta converts plasma loss into amps

A different kind of first was claimed on 1 July 2026 by Realta Fusion. The company says that on 19 June it became the first private fusion company to demonstrate direct energy conversion of plasma kinetic energy into electricity. It worked with the University of Wisconsin-Madison on the Wisconsin HTS Axisymmetric Mirror device, known as WHAM.

Direct energy conversion is not a new idea. The concept has been discussed in the fusion field for decades, with the aim of raising overall plant efficiency by pushing less energy through a thermal cycle that is capped by thermodynamics. Realta's approach leans on the physics of magnetic mirrors, which confine plasma in a field that leaks charged particles through a natural loss cone. Instead of treating that leak as a defect, Realta argues it is useful: the escaping particles carry energy that can be recovered electrically.

The hardware is a single-stage converter with three finely meshed grids: an electrically grounded grid, an electron repulsion grid and an ion collector grid. It is installed on WHAM's end-ring assembly in place of the center disk. During plasma operations it draws multiple amps at around 100 volts.

Realta is explicit that this is small. The power involved, the company says, is enough to illuminate a few lightbulbs. And it draws a line around what the result is not.

"This is neither a demonstration of net-electricity production nor large-scale conversion of fusion-born power directly into electricity," the post states. WHAM runs on deuterium only, so most of the converted energy comes from the input power used to heat and sustain the plasma, not from fusion reactions. Realta says the next step is scaling to multi-kilowatt and eventually multi-megawatt capability. The company's framing is "first make it work, then make it good."

That candour is unusual in a sector where press releases often blur the distance between a laboratory demonstration and a power plant. It also means the result should be read as an engineering proof of concept, not as a step toward commercial generation.

Thea Energy raises $100 million for a stellarator

Thea Energy, based in Kearny, New Jersey, announced on 27 May 2026 that it raised $100 million in Series B funding. The round was led by US Innovative Technology Fund, with participation from General Innovation Capital Partners, Linse Capital, Calm Ventures, Climate Capital, Divergent Capital, Emerald Technology Ventures, Gaingels, Idemitsu Kosan, Overlay Capital, Timescale Ventures and Whatif Ventures, among others. Existing investors including Alumni Ventures, Hitachi Ventures, Lowercarbon Capital, Mercator Partners, Orion Industrial Ventures, Prelude Ventures and Starlight Ventures also took part.

Thea's architecture is the stellarator, a magnetic confinement design that spun out of Princeton University and the Princeton Plasma Physics Laboratory in 2022. Stellarators have historically been harder to build than tokamaks because their magnets require complex three-dimensional shapes. Thea claims its planar coil design shifts that complexity from precision mechanical fabrication into software-defined controls.

The money is earmarked for magnet manufacturing capacity, including a second facility in northern New Jersey, and for siting and building "Eos," a large integrated stellarator intended to reach steady-state, power-plant-relevant conditions. Thea says it will select a site for Eos later this year and double its team. The company is targeting construction of its first "Helios" power plant before the end of the decade and says it is in discussions with more than a dozen power offtakers, hyperscalers and utility partners.

One credential behind the raise: Thea says it is the first awardee to receive Department of Energy certification of its power plant preconceptual design milestone, under the agency's Milestone-Based Fusion Development Program. It also says it has built and operated the first superconducting magnet array capable of producing the complex magnetic fields a commercial stellarator needs.

The public project still sets the clock

Against these private milestones sits ITER, the International Thermonuclear Experimental Reactor in southern France. CNET reported in May 2026 that the project carries an estimated cost of $22 billion and is designed to contain plasma at 150 million degrees Celsius, ten times hotter than the core of the Sun, inside a doughnut-shaped vacuum chamber.

The engineering problem is the temperature gradient. Superconducting magnets held a few degrees above absolute zero must sit next to one of the hottest environments ever created, separated by a thin heat shield. Cracks in the piping of that shield were found in 2020, along with welding distortions and pandemic disruption. CNET reports the result was a years-long delay and an additional $5 billion for repairs, while private startups multiplied around it.

ITER's defenders argue that this spending de-risks the field for everyone. Because it is publicly funded, its science is shared: every member state, more than 30 countries, gets access to what comes out of it, and its construction is building a global fusion supply chain. "Every problem ITER solves is one less problem private fusion companies will have to figure out," is how CNET frames the argument.

That is a reasonable position, and it is also the position of an institution under pressure. The private companies are not waiting. Helion has a Microsoft contract and a plant under construction. Thea has $100 million and a site selection to make. Realta has a few lightbulbs' worth of proven conversion and a stated plan to scale it.

None of these results is commercially decisive on its own. A temperature record is not a gain measurement, a direct conversion demo at 100 volts is not a generator, and a Series B is not a power plant. What the three announcements together show is a field that has stopped describing fusion as a distant prospect and started publishing intermediate engineering results in public. The grid, so far, has seen none of it.