Fusion's 2026 Scoreboard: Two Firsts, One Bigger Bill

Two privately funded fusion companies posted laboratory firsts in 2026. Neither one claims it has solved the commercial problem.

Helion, based in Everett, Washington, said on 13 February that its seventh-generation Polaris prototype had demonstrated measurable deuterium-tritium fusion and reached plasma temperatures of 150 million degrees Celsius. That beats the 100 million degrees Celsius the company recorded on its sixth-generation Trenta machine, a level the fusion industry generally treats as the threshold for a commercially relevant device. Helion began operating Polaris at the end of 2024 and says it is currently the only private machine to have used D-T fuel. The company holds regulatory approval to possess and use tritium for fusion demonstrations.

“We believe the surest path to commercializing fusion is building, learning and iterating as quickly as possible,” David Kirtley, Helion's co-founder and CEO, said in the announcement.

Not a finish line

The D-T campaign is one step in Polaris' testing programme, not the destination. Helion says it will keep raising temperatures in the machine to reach conditions for deuterium-helium-3, the fuel it intends to use in commercial operations. The distinction matters. A temperature record and a fusion reaction are not the same thing as electricity on the grid.

Outside reviewers quoted by Helion chose their words carefully. Ryan McBride, an inertial confinement fusion specialist who has worked at Sandia National Laboratories and the University of Michigan, said he had reviewed diagnostic data and called the evidence of D-T fusion and temperatures above 13 keV exciting. Jean Paul Allain, associate director for fusion energy sciences at the Department of Energy's Office of Science, said the Polaris data indicated strong progress. Getting fusion onto the grid, he added, would require approaches that allow rapid turnaround in design and testing.

Helion's commercial plan is already tied to a customer. In July 2025 the company began building on the site of Orion, its first commercial machine, in Malaga, Washington. According to the announcement, Orion will deliver electricity from fusion to the grid for Microsoft. A Chelan County hearing examiner has approved a permit for the plant, according to local coverage listed alongside the company's release.

Realta's amps, and what they are not

Realta Fusion reported a different kind of first. On 19 June, working with the University of Wisconsin-Madison on the Wisconsin HTS Axisymmetric Mirror device, the company demonstrated direct energy conversion of plasma kinetic energy into electricity. A converter installed on WHAM's end-ring assembly uses an electrostatic potential to slow charged particles leaving the mirror's loss cone, turning their kinetic energy into current. Realta says the assembly draws multiple amps at around 100 volts, enough to light a few bulbs.

The company is explicit about the limits. Its own write-up states that this is neither a demonstration of net electricity production nor large-scale conversion of fusion-born power, and that WHAM runs on deuterium only, so most of the converted energy comes from input power rather than from fusion. The stated philosophy is to make it work first, then make it good, with multi-kilowatt and eventually multi-megawatt scaling planned for later devices. Realta argues direct conversion could suit magnetic mirror plants because it sidesteps some of the efficiency losses of a thermal cycle.

The public benchmark keeps getting dearer

Against those private milestones sits ITER, the international tokamak under construction in southern France. CNET, in a May feature, put the project's estimated cost at $22 billion and described a doughnut-shaped vacuum chamber designed to hold plasma ten times hotter than the Sun's core, with superconducting magnets kept a few degrees above absolute zero. Cracks found in heat shield piping in 2020, welding distortions and pandemic disruption pushed the schedule back and added $5 billion in repair costs, according to the same report.

ITER's chief strategic advisor, Laban Coblentz, framed the collaboration bluntly in that article: “That China and Russia were going to collaborate with the US and Europe, and add in Korea, India, and Japan — that's either genius or insane.” The project's defenders argue its publicly funded science de-risks work for private firms. ITER has more than 30 member states, and CNET reports all of them will have access to the science it produces.

Money keeps moving on the private side too. Thea Energy, a stellarator developer spun out of Princeton University and Princeton Plasma Physics Laboratory in 2022, announced a $100 million Series B on 27 May, led by US Innovative Technology Fund, to expand magnet manufacturing and build its Eos integrated system. The company says it is the first awardee to receive Department of Energy certification of a preconceptual power plant design milestone.

Set the results next to each other and the pattern is clear. Private machines are now producing data that specialists will scrutinise, at temperatures and in configurations that were once the preserve of government laboratories. None of it yet shows a plant selling power. The gap between a record temperature and a meter reading remains the whole story.