Realta Fusion has reported a notable step forward in fusion energy, saying it successfully powered a lightbulb with electricity captured directly from its WHAM demonstration device on June 19. The Wisconsin-based startup says this is the first public demonstration by a private company of direct electricity conversion from a fusion reaction.
The approach is designed to make fusion systems more efficient by turning part of the reaction's energy into usable electricity without relying only on steam turbines. According to company co-founder and CEO Kieran Furlong, the method can help "take power from a plasma" and improve the economics of future reactors.
Realta says its prototype converter was attached to the end of the reactor and harvested enough alpha-particle energy to produce multiple amps at 100 volts, enough to light several bulbs. The company estimates the conversion process could reach about 90% efficiency, far above the roughly 33% efficiency associated with conventional steam turbines in today's fission systems.
The startup's commercial vision is to use this electricity to help heat the plasma inside the reactor, creating a more circular energy loop. Realta believes that, at scale, this design could raise total output by 20% to 30% and strengthen the path toward profitable fusion power.
While Realta may be the first to show this publicly, it is not alone in pursuing direct energy conversion. The concept is also part of the strategy at Helion, another fusion company working on similar ideas. Realta, which previously raised $36 million in a Series A round led by Future Ventures in 2025, says it is now preparing for its next funding phase.
This milestone suggests fusion could move closer to a more efficient and commercially practical energy model in the years ahead.