Realta Fusion Successfully Demonstrates Direct Energy Conversion (DEC) of Plasma Kinetic Energy into Electricity

Realta Fusion, decarbonizing industrial heat and power with compact, scalable, modular – CoSMo fusion™ – energy systems, led by Kieran Furlong, MBA, Cary Forest, PhD., Jay Anderson, PhD., Ben Lindley, PhD., Oliver Schmitz, PhD., and the team, in collaboration with partners at the University of Wisconsin-Madison demonstrated direct energy conversion (DEC) on the Wisconsin HTS Axisymmetric Mirror (WHAM) prototype fusion device. This is the first time a commercial fusion company has demonstrated DEC applied to a fusion plasma.

Direct Energy Conversion (DEC).

Direct Energy Conversion (DEC) is a process that converts the kinetic energy of charged particles in a fusion plasma directly into electricity, bypassing traditional heat-based thermal cycles.

By avoiding thermal conversion, DEC could improve overall system efficiency, which is typically limited by thermodynamic constraints in conventional power generation.

The approach has long been studied in fusion research and is considered especially relevant for magnetic mirror fusion concepts.

Magnetic Mirror Confinement and DEC.

Magnetic mirror fusion naturally produces a “loss cone” where some charged particles escape due to collisions. Using high-temperature superconducting magnets and higher mirror ratios helps reduce this loss and improve confinement.

Rather than treating this leakage as a limitation, it can be used productively. Escaping charged particles, along with helium ash and impurities, help keep the plasma clean, while also enabling Direct Energy Conversion (DEC) to recover their kinetic energy as electricity instead of heat.

In a deuterium-tritium system, neutrons are still converted into heat, while charged alpha particles can be partially confined and later harvested through DEC. This hybrid approach combines thermal and direct conversion pathways to improve overall system efficiency and potentially offset much of the input power.

WHAM Direct Energy Conversion (DEC) Demonstration.

A direct energy converter was integrated into WHAM’s end-ring assembly by replacing the center disk. The device slows charged particles exiting through the magnetic mirror’s loss cone using an electrostatic potential, converting their kinetic energy directly into electricity during plasma operation.

The current prototype is a single-stage system consisting of three fine mesh grids: a grounded grid, an electron repulsion grid, and an ion collector grid. During operation, it produces multiple amps at ~100 volts, enough to power small loads, with ongoing work to increase output.

This demonstration shows direct conversion of a portion of input plasma power, primarily from externally supplied heating rather than fusion-born energy, into electricity. In future high-gain fusion systems, a larger share of this converted power is expected to come directly from fusion products, particularly alpha particles in deuterium-tritium (DT) operation.

This result does not represent net electricity production or large-scale fusion power conversion. Those milestones are planned for future devices.

The Path Ahead for DEC at Realta.

Following the WHAM demonstration, the focus is on scaling Direct Energy Conversion (DEC) from a prototype system to multi-kW and ultimately multi-MW capability in future devices. This progression is guided by a “first make it work, then make it good” philosophy, with the broader goal of enabling commercially relevant magnetic mirror fusion power plants.

DEC offers a key advantage in deuterium-tritium (DT) mirror systems by recovering energy from neutral beam, electron cyclotron, and ion cyclotron heating more efficiently than traditional thermal cycles. At scale, this could enable net-electric conditions at lower fusion gain (Qsci) compared to other confinement approaches. While not strictly required for reactor operation, DEC provides additional flexibility and efficiency improvements for future power plant designs.

Beyond first-generation DT systems, DEC also opens pathways for advanced fusion fuels such as catalyzed D-D or D-³He, where a larger fraction of energy is carried by charged particles that can be directly converted into electricity. This could reduce reliance on thermal systems and potentially eliminate large-scale tritium breeding requirements, lowering complexity and cost in future fusion power plants.