Helion

Private company developing fusion power plants.

Fusion energyClean energyDeep tech

Active^{Source [4]}Last verified Oct 2, 2026

About Helion

Helion is a private company developing fusion power plants, with the stated mission to fully satisfy the world's need for clean, abundant energy. It is based in Everett, Washington, having moved there from Redmond in 2022.^{Source [1]}^{Source [2]}

It has built a series of fusion prototypes. Its sixth, Trenta, reached 100 million degrees Celsius, and its seventh, Polaris, reached 150 million degrees Celsius on deuterium-tritium fuel in early 2026.^{Source [1]}^{Source [6]}^{Source [7]}

In 2023 Helion signed what it called the world's first fusion power purchase agreement, to supply Microsoft with at least 50 MW from 2028 with Constellation as power marketer, and it began building its first plant, Orion, in Malaga, Washington in July 2025.^{Source [8]}^{Source [6]}

Sam Altman was an investor and chairman from 2015 and led a $500 million round in 2021. He stepped down as board chair in March 2026 so that Helion and OpenAI could explore a partnership. In June 2026 Helion raised a $465 million Series G led by Thrive Capital at a reported $15.5 billion valuation.^{Source [2]}^{Source [9]}^{Source [4]}^{Source [3]}

Watch

Helion hits new fusion milestone: D-T fusion and 150M°C plasma temperatures by Helion on YouTube

What happened

Founded in Washington State in 2013 by David Kirtley, Chris Pihl, John Slough, George Votroubek and Anthony Pancotti. Sam Altman was an investor and chairman from 2015, led a $500 million round in 2021, and stepped down from the board in March 2026 as Helion and OpenAI explored working together. The company is still active, is building its first plant for Microsoft, and announced a $465 million Series G round in June 2026.^{Source [1]}^{Source [2]}^{Source [9]}^{Source [4]}

Timeline

2026-06Raised a $465 million Series G led by Thrive Capital.^{Source [4]}^{Source [3]}
2026-03Sam Altman stepped down as board chair as Helion and OpenAI explored a partnership.^{Source [9]}
2026-02Polaris reached 150 million degrees Celsius on deuterium-tritium fuel.^{Source [7]}
2025-07Began construction of Orion in Malaga, Washington.^{Source [6]}
2025-01Raised a $425 million Series F.^{Source [5]}
2023-09Announced a collaboration with Nucor on a 500 MWe fusion plant.^{Source [4]}
2023-05Signed a fusion power purchase agreement with Microsoft for power from 2028.^{Source [8]}
2021-11Raised $500 million led by Sam Altman.^{Source [2]}
2021-06Reached 100 million degrees Celsius fuel temperature with Trenta.^{Source [4]}
2015Sam Altman became an investor and chairman.^{Source [2]}
2013Founded in Washington State.^{Source [1]}

Products and brands

Orion: First commercial fusion power plant, under construction in Malaga, Washington, to supply Microsoft.^{Source [6]}^{Source [1]}
Polaris: Seventh-generation fusion prototype meant to demonstrate electricity from fusion.^{Source [1]}^{Source [2]}

How it makes money: Plans to sell electricity from its fusion plants to customers under power purchase agreements, starting with Microsoft and steelmaker Nucor.^{Source [8]}^{Source [1]}

Leadership

David Kirtley	Co-founder and CEO^{Source [1]}
Chris Pihl	Co-founder and CTO^{Source [1]}
George Votroubek	Co-founder and Chief Scientist^{Source [1]}
Prag Jain	CFO^{Source [1]}

Funding and financials

Valuation: $15.5 billion post-money (June 2026, reported)^{Source [4]}^{Source [3]}

Date	Round	Amount	Investors
2026-06	Series G^{Source [4]}^{Source [3]}	$465 million	Led by Thrive Capital
2025-01	Series F^{Source [5]}^{Source [4]}	$425 million	Lightspeed Venture Partners, SoftBank Vision Fund 2, with Sam Altman and others
2021-11	Series E^{Source [2]}	$500 million, plus up to $1.7 billion tied to milestones	Led by Sam Altman, with Mithril Capital, Capricorn Investment Group and Dustin Moskovitz

People on Founded, and where they went next

1 person on record, connected to 7 other companies.

Person	Here	Also built
Sam Altman	Chairman2015 to 2026	Merge LabsActiveTools for Humanity2019 to nowActiveOpenAI2015 to nowActiveOklo2015 to 2025IPOY Combinator2011 to 2019ActiveHydrazine Capital2012ActiveLoopt2005 to 2012Acquired

Sources

About, Helion. Accessed Oct 2, 2026.
Helion Raises $500 Million, Targets 2024 for Demonstrating Net Electricity from Fusion, Helion, 2021-11-05. Accessed Oct 2, 2026.
Helion's $465M Raise Signals Growing Fusion Demand, Ventureburn, 2026-06. Accessed Oct 2, 2026.
Newsroom, Helion. Accessed Oct 2, 2026.
Helion raises $425M to help build a fusion reactor for Microsoft, TechCrunch, 2025-01-28. Accessed Oct 2, 2026.
Helion secures land and begins building site of world's first fusion power plant, Helion, 2025-07-30. Accessed Oct 2, 2026.
Fusion startup Helion hits blistering temps as it races toward 2028 deadline, TechCrunch, 2026-02-13. Accessed Oct 2, 2026.
Helion announces world's first fusion PPA with Microsoft, Helion, 2023-05-10. Accessed Oct 2, 2026.
Sam Altman-backed fusion startup Helion in talks to sell power to OpenAI, TechCrunch, 2026-03-23. Accessed Oct 2, 2026.

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