A US startup developing hypervelocity projectile fusion — using electromagnetic railguns to launch plasma projectiles that converge and compress a central fuel target to ignition conditions.
NearStar Fusion is a US startup pursuing a novel approach to inertial fusion energy based on hypervelocity plasma projectiles launched by electromagnetic railguns. Rather than using lasers or pulsed-power Z-pinches to compress fuel, NearStar accelerates multiple plasma "bullets" to extreme velocities (tens to hundreds of km/s) and directs them inward to converge on a central fuel target, compressing and heating it to fusion conditions.[1]
NearStar's concept employs an array of plasma railguns arranged symmetrically around a reaction chamber. Each railgun accelerates a compact plasma projectile (sometimes called a plasma liner) to hypervelocity. When the projectiles converge simultaneously on the central fuel target, their kinetic energy is converted into the thermal energy and compression needed to initiate fusion. The approach can be thought of as a kinetic-energy-driven analog to laser ICF, with railgun-launched plasma replacing photon pressure.[1]
The plasma liner concept was originally studied at Los Alamos National Laboratory (the PLX — Plasma Liner Experiment) and has theoretical appeal because electromagnetic launchers can be highly efficient, repetitive, and powered by relatively conventional pulsed electrical systems. NearStar is working to scale the concept from laboratory demonstration to fusion-relevant parameters.[2]
Achieving symmetric convergence of multiple plasma projectiles with the uniformity needed for efficient compression is a central engineering challenge. Any asymmetry seeds Rayleigh-Taylor instabilities that can prevent adequate compression. Additionally, the projectiles must maintain coherence during flight and arrive with precise simultaneity (within nanoseconds). NearStar must also demonstrate that plasma projectiles at achievable velocities carry sufficient kinetic energy to compress D-T fuel to ignition conditions.[2]
If successful, the railgun approach offers several practical benefits for a power plant: electromagnetic launchers are mechanically robust, have no consumable optics, can fire repetitively at power-plant-relevant rates, and draw on mature pulsed-power technology. The fuel target is effectively "standoff" — separated from the chamber walls by the converging projectiles — which may ease first-wall survival compared to direct-drive laser ICF.[3]
NearStar Fusion is in the early development phase, advancing railgun performance and plasma projectile formation toward fusion-relevant parameters. The company is part of a growing cohort of startups exploring alternatives to both mainstream magnetic confinement and traditional laser-driven ICF.[3]