Private Fusion Startup Achieves First-Ever Direct Conversion of Plasma Energy to Electricity

Realta Fusion has successfully demonstrated the first direct conversion of plasma kinetic energy into electricity by a private fusion company. In a June 19, 2026 experiment on its WHAM (Wisconsin HTS Axisymmetric Mirror) device, the system drew several amps of current at approximately 100 volts, enough to power a handful of incandescent lightbulbs. However, the company is explicit about the limits of the demonstration: the reactor does not yet burn deuterium-tritium fuel, meaning the converter harvested input power used to heat the plasma rather than the alpha particles of a self-sustaining fusion reaction. It is a proof of concept, not a demonstration of net energy gain.[1][2][3]

Traditional power plants—whether coal, fission, or most proposed fusion designs—generate electricity through a thermal cycle. They use heat to boil water, spin a steam turbine, and drive a generator. That process is inherently lossy, converting only about 33% of the thermal energy into electricity. Direct energy conversion (DEC) bypasses the thermal cycle entirely. Instead of capturing heat, a DEC system harvests the kinetic energy of charged particles—specifically the fast-moving helium nuclei, or alpha particles, produced during fusion.[1][2][4]

Realta achieved this by bolting a prototype electrostatic converter onto the end-ring assembly of its magnetic mirror reactor. As charged particles escape through the magnetic mirror's "loss cone," they pass through three finely meshed grids: an electrically grounded grid, an electron repulsion grid, and an ion collector grid. These grids slow the particles down, building up a voltage and driving an electrical current. By capturing energy directly from the particles, Realta estimates DEC can achieve roughly 90% efficiency.[1][3][4]

The efficiency leap from 33% to 90% could fundamentally alter the economics of commercial fusion. Every fusion plant must consume power to heat its plasma and sustain the reaction. By capturing the energy of charged particles and recirculating it immediately as electricity, a plant can offset its own startup costs. Realta's CEO Kieran Furlong estimates that this "flywheel of electricity" could boost a commercial plant's total output by 20% to 30%, potentially reducing the projected cost per kilowatt-hour by 10% to 20%.[1][2][3]

The concept of direct conversion was theorized in the 1970s, but it is now becoming a central strategy for a subset of fusion startups seeking an economic edge over massive, tokamak-style reactors. Helion Energy, backed by Sam Altman, has built its entire commercial strategy around an induction-based DEC method, though it has not yet demonstrated the capability publicly. Realta's test makes it the first private firm to prove that the wiring holds on an operating fusion machine.[2][3]

The next hurdle is scaling the converter from hundreds of watts to tens of megawatts. Realta plans to integrate the technology into its first-generation commercial plants targeted for the mid-2030s. In those early plants, a traditional steam cycle will likely still handle the bulk of the power generation, while the DEC system will specifically harvest the 20% of fusion energy carried by charged particles to power the reactor itself.[1][2][3]

If neutron direct energy conversion becomes viable, it could also open up alternative fuel options. Realta's chief scientific officer noted that the approach could enable catalyzed deuterium-deuterium or deuterium-helium-3 fuels. This would reduce the industry's dependence on tritium breeding, which remains a significant logistical and cost challenge for standard deuterium-tritium fusion power.[3]

For now, the achievement remains modest but highly legible: a few glowing bulbs, powered by a converter on a machine that is not yet a power plant. Yet in an industry where milestones have historically been simulations or single-shot lab records, demonstrating an engineering shortcut that fundamentally changes the math of grid-scale economics is a critical step forward.[1][4]