Nuclear Fusion Ignition Achieved in US Laboratory

A breakthrough fusion demonstration at Lawrence Livermore National Laboratory produced more energy than it used—a historic first.

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 on 5 December.
Lawrence Livermore National Laboratory

The US Department of Energy (DOE) and DOE’s National Nuclear Security Administration (NNSA) are touting a breakthrough in fusion energy from its Lawrence Livermore National Laboratory (LLNL) where for the first time, researchers have produced more energy from fusion than was used to create it. The fusion ignition is being called a major scientific breakthrough decades in the making that will pave the way for advancements in national defense and the future of clean power.

On 5 December, a team at LLNL’s National Ignition Facility (NIF) conducted the first controlled fusion experiment in history to reach this milestone, also known as scientific energy breakeven, meaning it produced more energy from fusion than the laser energy required to drive the process. This historic, first-of-its kind achievement will provide unprecedented capability to support NNSA’s Stockpile Stewardship Program and will provide invaluable insights into the prospects of clean fusion energy.

Fusion is what drives our sun and the stars. To create fusion ignition, the NIF’s laser energy is converted into X-rays inside the hohlraum—a cavity whose walls are in radiative equilibrium with the radiant energy within the cavity—which then compress a fuel capsule until it implodes, creating a high-temperature, high-pressure plasma.


The hohlraum that houses the type of cryogenic target used to achieve ignition at LLNL’s National Ignition Facility. SOURCE: Lawrence Livermore National Laboratory

“Monday, December 5, 2022, was a historic day in science thanks to the incredible people at Livermore Lab and the National Ignition Facility,” said NNSA Administrator Jill Hruby. “In making this breakthrough, they have opened a new chapter in NNSA’s Stockpile Stewardship Program.”

US Secretary of Energy Jennifer M. Granholm called the fusion ignition “a landmark achievement” for the researchers and staff at the NIF who have dedicated their careers to seeing fusion ignition become a reality, and added that this milestone will “undoubtedly spark even more discovery.”

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 US. Combined with private-sector investment, there is a lot of momentum to drive rapid progress toward fusion commercialization.

“The pursuit of fusion ignition in the laboratory is one of the most significant scientific challenges ever tackled by humanity, and achieving it is a triumph of science, engineering, and most of all, people,” said LLNL Director Kim Budil. “Crossing this threshold is the vision that has driven 60 years of dedicated pursuit—a continual process of learning, building, expanding knowledge and capability, and then finding ways to overcome the new challenges that emerged. These are the problems that the US national laboratories were created to solve.”

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 in Livermore, California—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.