Startup Powers Lightbulbs from Fusion Device in June Test

Realta Fusion powered several lightbulbs on June 19 by harvesting electricity directly from its WHAM demonstration fusion device. The Wisconsin-based startup attached a prototype converter to the end of the reactor and captured enough alpha-particle power to produce multiple amps at 100 volts.

@techcrunch reported that the company believes it is the first private firm to publicly demonstrate direct electricity harvesting from a fusion device.

Realta plans to use the direct-conversion method to heat plasma inside its reactor. Furlong estimates the process is about 90 percent efficient, compared with roughly 33 percent efficiency for steam turbines in current fission plants. About 20 percent of the energy released in the deuterium-tritium reactions the company intends to use consists of charged helium nuclei, or alpha particles.

On a commercial scale, Furlong projects that recirculating this electricity could increase a power plant’s total output by 20 to 30 percent. Realta Fusion’s WHAM device is designed to test the magnetic-mirror approach to fusion confinement. The company raised $36 million in a Series A round led by Future Ventures in 2025 and is currently seeking additional funding.