David Kirtley trained in aerospace engineering at the University of Michigan. He worked at the Air Force Research Laboratory and NASA Glenn before joining MSNW in Redmond, Washington, in 2008, where he led fusion work. He has said he came to fusion by thinking about the overlap of energy and space travel.
Helion was founded in 2013 by Kirtley, John Slough, Chris Pihl and George Votroubek. Early funding was about $7 million from NASA, the Department of Energy and the Department of Defense, followed by $1.5 million from private investors in August 2014 through Y Combinator and Mithril Capital.
In November 2021 Helion raised a $500 million Series E, with $1.7 billion more in milestone-linked commitments, led by Sam Altman. Microsoft agreed in May 2023 to buy 50 MWe from 2028. The company's own 2021 target of showing net electricity in 2024 was not met.
Polaris, the seventh prototype, was finished in late 2024. On 13 February 2026 Helion reported deuterium-tritium fusion at 150 million degrees C. A $500 million Series G closed in September 2026, and Orion, a 50 MW plant in Chelan County, Washington, is planned to be operating by 2028.