Helion's D-T First, Realta's Direct Conversion: Private Fusion Posts Two Results

Two private fusion companies posted results months apart. Helion's newsroom post, dated 13 February 2026, says Polaris demonstrated measurable deuterium-tritium (D-T) fusion and plasma temperatures of 150 million degrees Celsius. Realta Fusion's post, published 1 July 2026, says that on 19 June it became the first private fusion company to demonstrate direct energy conversion of plasma kinetic energy into electricity, on the WHAM device at the University of Wisconsin-Madison. Neither company claims net electricity. Read the fine print in both cases.

Helion's own account is careful about what the D-T campaign does and does not establish. Polaris, the company's seventh-generation prototype, began operating at the end of 2024. In January it became the first and currently only private fusion machine to use deuterium-tritium fuel, according to the company. Helion says it was also the first company to receive regulatory approval to possess and use tritium for demonstrating fusion energy production. D-T operation is one step in the Polaris testing program, not the destination. Helion says it will keep raising temperatures to reach optimal conditions for deuterium-helium-3 fusion, the fuel it intends to use commercially.

The 150 million degree figure doubles Helion's previous mark. The company says it broke its own industry record of 100 million degrees Celsius set by Trenta, its sixth-generation prototype. It notes that the industry treats 100 million degrees as the threshold for a commercially relevant fusion machine.

Helion published outside comment alongside its own claims. Jean Paul Allain, Associate Director for Fusion Energy Sciences in the Department of Energy's Office of Science, said he was impressed with "the pace at which we are de-risking our path to fusion commercialization," and pointed to "record-setting temperatures and gains from the fuel mix in their system." Ryan McBride, who has worked on inertial confinement fusion and pulsed power and held a department manager post at Sandia National Laboratories, said he had reviewed diagnostic data and called evidence of D-T fusion and temperatures exceeding 13 keV or 150 million degrees Celsius "exciting."

Realta's result is a different milestone, and the company is unusually explicit about its limits. Direct energy conversion slows charged particles leaving the mirror's loss cone with an electrostatic potential and turns their kinetic energy into current. On WHAM, a single-stage converter made of three meshed grids drew multiple amps at around 100 volts, enough to light a few bulbs, according to Realta. The company states plainly that this is neither net electricity production nor large-scale conversion of fusion-born power, and that those milestones belong to future devices.

Context matters for both. CNET's May 2026 look inside ITER describes a $22 billion publicly funded machine that has absorbed years of delay after cracks were found in heat shield piping in 2020. It notes that private startups have multiplied while many hope to beat ITER to major milestones. ITER's chief strategic advisor, Laban Coblentz, is quoted saying the science is shared: "It is the knowledge of the world," per Javier Artola, a scientist modelling ITER's plasma.

Money is moving into the private side regardless. Thea Energy said on 27 May 2026 that it raised a $100 million Series B led by USIT, with General Innovation Capital Partners and Linse Capital participating, to expand magnet manufacturing and build its Eos integrated stellarator. Helion's own path to the grid runs through Orion, its first commercial machine, which the company says it began building in Malaga, Washington, in July 2025 to deliver fusion electricity to Microsoft.