# Sam Altman's Fusion Power Bet Just Got Hotter Than The Sun

_Friday, June 26, 2026 at 9:47 PM EDT · science · Latest · Tier 2 — Notable_

![Sam Altman's Fusion Power Bet Just Got Hotter Than The Sun — Primary](https://imageio.forbes.com/specials-images/imageserve/699798730c710f9118b003d9/0x0.jpg?format=jpg&height=900&width=1600&fit=bounds)

Helion Energy, a Washington-based fusion power startup, announced that its reactor reached plasma temperatures of 150 million degrees Celsius. At that level the reactor fused deuterium and tritium atoms. The temperature is described as 10 times hotter than the surface of the Sun.

The milestone brings the reactor closer to the conditions needed for a fusion reaction to produce more energy than is supplied to it. William McCarthy, a physics professor at Worcester Polytechnic Institute, said the result shows Helion's technology is in the race but noted the company still must demonstrate net energy gain.

Helion has raised more than one billion dollars from investors including Sam Altman, Softbank and Lightspeed Ventures. The company is valued at more than 5.4 billion dollars according to Pitchbook. It holds a contract to supply power to Microsoft data centers in Washington beginning in 2028.

## Sources

- [Forbes](https://www.forbes.com/sites/the-prototype/2026/02/20/sam-altmans-fusion-power-bet-just-got-hotter-than-the-sun/)

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Retrieved: 2026-06-27T06:00:20.477Z
Publisher: Tech & Business (techandbusiness.org)