The US Department of Energy (DOE) and DOE’s National Nuclear Security Administration (NNSA) announced the achievement of fusion ignition at Lawrence Livermore National Laboratory (LLNL). On 5 December, a team at LLNL’s National Ignition Facility (NIF) conducted the first controlled fusion experiment in history to reach this milestone—known as scientific energy breakeven.

LLNL’s experiment surpassed the fusion threshold by delivering 2.05 megajoules (MJ) of energy to the target, resulting in 3.15 MJ of fusion energy output, demonstrating for the first time a most fundamental science basis for inertial fusion energy (IFE).

Many advanced science and technology developments are still needed to achieve simple, affordable IFE to power homes and businesses, and DOE is currently restarting a broad-based, coordinated IFE program in the United States.

The target chamber of LLNL’s National Ignition Facility, where 192 laser beams delivered more than 2 million joules of ultraviolet energy to a tiny fuel pellet to create fusion ignition.

The hohlraum that houses the type of cryogenic target used to achieve ignition.

Fusion is the process by which two light nuclei combine to form a single heavier nucleus, releasing a large amount of energy. In the 1960s, a group of pioneering scientists at LLNL hypothesized that lasers could be used to induce fusion in a laboratory setting. Led by physicist John Nuckolls, who later served as LLNL director from 1988 to 1994, this idea became inertial confinement fusion, kicking off more than 60 years of research and development in lasers, optics, diagnostics, target fabrication, computer modeling and simulation and experimental design.

To pursue this concept, LLNL built a series of increasingly powerful laser systems, leading to the creation of NIF, the world’s largest and most energetic laser system. NIF—located at LLNL—is the size of a sports stadium and uses powerful laser beams to create temperatures and pressures like those in the cores of stars and giant planets, and inside exploding nuclear weapons.

To create fusion ignition, the National Ignition Facility’s laser energy is converted into X-rays inside the hohlraum, which then compress a fuel capsule until it implodes, creating a high temperature, high pressure plasma.

Achieving ignition was made possible by dedication from LLNL employees as well as countless collaborators at DOE’s Los Alamos National Laboratory, Sandia National Laboratories and Nevada National Security Site; General Atomics; academic institutions, including the University of Rochester’s Laboratory for Laser Energetics, the Massachusetts Institute of Technology, the University of California, Berkeley, and Princeton University; international partners, including the United Kingdom’s Atomic Weapons Establishment and the French Alternative Energies and Atomic Energy Commission; and stakeholders at DOE and NNSA and in Congress.