Helion Energy, a U.S. fusion start-up, announced that its seventh‑generation Polaris prototype has heated plasma to roughly 150 million degrees Celsius — a landmark the company says represents about three‑quarters of the temperature it believes necessary for a commercial fusion plant. The result follows an earlier industry record by Helion’s sixth‑generation device, Trenta, which reached 100 million degrees, and is being framed as a tangible step toward the company’s stated plan to supply Microsoft with electricity from a 50‑megawatt plant named Orion by 2028.
The technical route Helion pursues differs from the better‑known tokamak approach. Its reactors use a field‑reversed configuration (FRC): plasma is formed in two toroidal blobs injected from the ends of an hourglass‑shaped chamber, accelerated toward each other, then magnetically compressed as they merge. The compression stage raises temperatures from tens of millions of degrees to the 150 million degree level in less than a millisecond, according to the company.
Helion also uses an unconventional electricity‑capture method. Rather than relying on fusion heat to run steam turbines, the firm aims to convert the pulses’ magnetic effects directly into electrical current. Each fusion pulse exerts a reaction on the reactor’s magnetic coils and induces a collectable current, which could allow a compact, pulse‑driven generator architecture if the concept scales as promised.
Fuel choice is central to Helion’s strategy. The company says Polaris achieved a measurable deuterium–tritium (D–T) fusion reaction, but its longer‑term goal is deuterium–helium‑3 (D–He3) fusion because the charged particles produced are easier to convert directly into electricity and generate fewer neutrons. Helium‑3 is scarce on Earth and commonly invoked as a lunar resource; Helion plans to breed and purify He‑3 from inevitable deuterium–deuterium (D–D) reactions on site and re‑use it as fuel.
The commercial and financial context sharpens the stakes. Helion has attracted high‑profile backers including Sam Altman and SoftBank, and after a roughly $425 million Series F last year the firm’s valuation crossed the $5 billion mark. The company’s partnership with Microsoft and its bold 2028 target place Helion well ahead of many rivals, most of which project commercialization in the 2030s or later.
Despite the milestone, substantial technical and programmatic gaps remain. The press release and past demonstrations show progress on temperature and measurable fusion events, but they do not yet demonstrate sustained net electricity output, a practical repetition rate, component longevity under neutron flux and thermal cycling, or the full fuel‑cycle logistics for D–He3. Helion’s FRC design demands much higher plasma temperatures than many tokamaks — roughly double — which raises engineering challenges for materials, magnets and control systems.
If Helion can combine repeatable, net‑positive pulses with its direct conversion approach and a working plan to produce or recycle He‑3 at scale, the commercial implications would be profound: a compact fusion generator with a fast path to grid supply would upend electricity markets, accelerate decarbonization and redraw strategic technology priorities. Yet commercialization at utility scale remains contingent on proving a clutch of engineering, regulatory and economic realities that have halted many fusion promises in the past.