What is inertial confinement fusion?
Inertial confinement fusion is an approach to fusion that implodes a tiny capsule of hydrogen fuel, usually with powerful lasers. The implosion is so quick that the fuel fuses before it has time to fly apart.
Also known as: ICF, laser fusion, inertial fusion
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How it works
Lawrence Livermore National Laboratory (LLNL) defines inertial confinement fusion as an approach that implodes a fuel capsule. The implosion is so rapid, it says, that the inward-moving fuel's inertia allows fusion before the particles can scatter. At LLNL's National Ignition Facility (NIF), the fuel is deuterium and tritium, two forms of hydrogen. The implosion there exceeds 400 kilometers per second.
The glossary describes two laser methods. In direct drive, beams light the capsule from all directions. In indirect drive, used at NIF, beams enter a hollow metal cylinder about the size of a pencil eraser, called a hohlraum. The resulting x-rays blow off the capsule's surface, producing a rocket-like implosion. NIF uses 192 beams that deliver about 2 million joules of ultraviolet energy. The University of Rochester's 60-beam OMEGA laser supports direct-drive experiments.
The driver need not be a laser. Nuclear Newswire reported in July 2026 that LLNL and Pacific Fusion had passed 3,000 shots on a prototype pulsed-power generator. It said the generator stores electrical energy, releasing it in bursts lasting billionths of a second.
Where it came from
The idea dates to the 1960s, when LLNL scientists led by John Nuckolls proposed using lasers to induce fusion in the laboratory, according to DOE. On December 5, 2022, NIF delivered 2.05 megajoules (MJ) of laser energy to a target and produced 3.15 MJ of fusion energy, a first that DOE calls scientific energy breakeven.
Where things stand in 2026
LLNL lists NIF's highest yield as 8.6 MJ from 2.08 MJ of laser energy on April 7, 2025, a target gain of 4.13. Its latest entry as of October 6, 2026, is an 11th ignition on June 20, 2026, yielding 7.9 MJ at a gain of about 3.8.
Those ratios count only laser energy delivered to the target. Osaka University physicist Shinsuke Fujioka wrote a February 2024 commentary in Physics Magazine. He said the reported 2022 yield was well below the 300 to 500 MJ of electrical energy needed to run NIF's lasers. LLNL says a power plant would have to fire 5 to 20 times per second.
LLNL said on April 14, 2026 that it was partnering with startup Inertia Enterprises under three agreements covering laser development and fusion targets. TechCrunch reported that Inertia, which raised a $450 million Series A in February 2026, was also licensing almost 200 of the lab's patents.
Sources
- Glossary, Lawrence Livermore National Laboratory
- Achieving Fusion Ignition, Lawrence Livermore National Laboratory
- How NIF Works, Lawrence Livermore National Laboratory
- Omega Laser Facility, University of Rochester Laboratory for Laser Energetics
- LLNL and Pacific Fusion achieve 3,000-shot milestone with Sirius pulsed-power prototype, American Nuclear Society, Nuclear Newswire
- DOE National Laboratory Makes History by Achieving Fusion Ignition, U.S. Department of Energy
- Nuclear-Fusion Reaction Beats Breakeven, Physics Magazine, American Physical Society
- Exploring Energy Security, Lawrence Livermore National Laboratory
- LLNL Partners with Inertia to Develop Fusion Energy Technology, Lawrence Livermore National Laboratory
- Inertia moves to commercialize one of the world's most elaborate science experiments, TechCrunch
