inertial confinement fusion (ICF) achieves 📝fusion by compressing a fuel capsule so quickly that the fuel's own inertia holds it together long enough to burn, as at the National Ignition Facility.
Its near-neighbor is 📝magnetic confinement fusion (MCF), and the two approaches occupy opposite corners of parameter space: where magnetic confinement holds a diffuse 📝plasma with fields for seconds or longer, inertial confinement abandons steady confinement entirely, crushing a millimeter-scale capsule of 📝deuterium-📝tritium fuel to densities far beyond that of lead and burning it in less than a billionth of a second — before the exploding fuel can fly apart.
The compression works like a spherical rocket. Intense laser or X-ray energy ablates the capsule's outer surface, and the blow-off drives the remaining shell inward at several hundred kilometers per second. Two coupling schemes divide the field: direct drive, in which laser beams strike the capsule itself, and indirect drive, in which the beams first fill a small metal cavity called a hohlraum that re-radiates their energy as X-rays. The National Ignition Facility, a 192-beam indirect-drive laser at Lawrence Livermore National Laboratory, achieved the first laboratory 📝ignition in December 2022, releasing 3.15 megajoules of fusion energy from 2.05 megajoules of delivered laser light. Turning that result into a power plant still requires orders-of-magnitude gains in repetition rate, laser efficiency, and target economics.