Helion Hits Fusion Milestone in Race to Power Microsoft

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Helion, a fusion energy startup, has reached a critical milestone in its quest to commercialize fusion power. The company's Polaris prototype reactor has achieved a temperature of 150 million degrees Celsius, about three-quarters of the level Helion believes is required for a commercial fusion power plant. This breakthrough validates the core plasma performance assumptions and narrows the gap toward commercial-scale operation. Helion is racing to meet a 2028 deadline to supply 50 megawatts of fusion-generated electricity to Microsoft, putting it on a faster timeline than most fusion competitors.

Why it matters

Fusion power has long been considered the 'holy grail' of renewable energy, with the potential to provide abundant, clean, and safe electricity. Helion's progress represents a significant step toward realizing this potential, as the company aims to be one of the first to bring fusion power to the commercial grid. The race to commercialize fusion is heating up, with billions in venture capital flowing into the sector, underscoring the high stakes and transformative impact fusion could have on the global energy landscape.

The details

Helion's Polaris reactor is now running on deuterium-tritium fuel, a mix of two hydrogen isotopes. The company says it is the first fusion startup to operate a prototype this way, leading to a dramatic increase in fusion power output as heat. The milestone validates Helion's core plasma performance assumptions and narrows the gap toward commercial-scale operation. To reach commercial viability, Helion is targeting 200 million degrees Celsius as the 'sweet spot' for operating a fusion power plant. The company's ambitions are not just theoretical, as it has a contract to supply 50 megawatts of electricity to Microsoft starting in 2028, using its Orion commercial reactor, not the Polaris prototype.

• Helion's Polaris reactor reached 150 million degrees Celsius in February 2026.
• Helion has a contract to supply 50 megawatts of fusion-generated electricity to Microsoft starting in 2028.

What they’re saying

What’s next

Helion must continue to refine its Polaris prototype and construct its Orion commercial reactor to meet the 2028 deadline to supply 50 megawatts of fusion-generated electricity to Microsoft.