On a University of Wisconsin Madison magnetic mirror device called WHAM, a startup called Realta captured a few amps at roughly 100 volts directly from charged plasma particles, sidestepping the heat to steam to turbine pathway most fusion plants
Realta Fusion pulled electrical current straight from a fusion plasma this month without first converting it to heat, steam, or turbine rotation. The experiment ran on the University of Wisconsin-Madison's WHAM magnetic mirror device, according to the company's announcement and a follow-up report in the American Nuclear Society on July 6.
It is the first time a private fusion company has demonstrated direct energy conversion on a magnetic mirror, Realta says, corroborated by TechCrunch's June 30 write-up. The captured current ran at multiple amps and roughly 100 volts. None of it came from steam. None of it was net electricity either: most of the captured power came from energy injected into the plasma to keep it hot, not from fusion reactions themselves.
Today's fusion power plant designs, from the ITER tokamak to most private-sector concepts, plan to imitate the thermal pathway that fission has used since the 1960s: capture heat, boil water, drive a turbine, generate current. Realta's result, at watts instead of megawatts, sidesteps that entire chain.
A demonstration at this scale does not change fusion economics. It changes the engineering target. Tokamak-centric design has spent sixty years solving heat-transfer problems. A mirror-plus-DEC design, if it scales, would be solving a particle-flow problem instead: contain hot plasma, capture its escaping particles, and scale the conversion stage without losing efficiency.
In a magnetic mirror device, plasma particles stream out along the magnetic field lines at high speed. Expand those particles through a decelerating electric field and the kinetic energy converts to electrical current without the temperature ever falling through steam. The technique is called direct energy conversion.
A 2008 IAEA fusion energy conference paper traces the lineage of the underlying physics, which has been studied since the late 1950s. Realta is the first private company to run that approach end-to-end on a working mirror device.
Magnetic mirrors use two strong magnetic "bottles" at each end of a chamber to bounce plasma back toward the center, rather than wrapping it in a closed loop the way a tokamak does. The approach was largely abandoned by the major fusion programs in the 1970s because confinement was poor compared with the tokamak. WHAM is built around high-temperature superconducting magnets, which is why a university lab can run a mirror at conditions that would have been impractical with older copper-coil machines.
If DEC and mirrors dovetail, the engineering implication is a fusion plant that is mechanically simpler and potentially cheaper than a tokamak-plus-steam-plant combination. That is a long way from a real cost figure. WHAM is an experiment, not a prototype, and the device-level numbers still trace back to Realta and UW-Madison rather than to an independent measurement. Fusion-report analysts and the ANS piece both flag the same uncertainty: the demonstration is real, but the path from a few amps at 100 volts to a commercial-scale magnetic mirror plant will require repeating the experiment at higher power, on larger devices, with independent diagnostics.
Realta says its next device is already in design. The first independent third-party measurement of its output, not the company's own ammeter, will be the more telling data point.