A chamber lift in the National Ignition Facility.
Credit: Damien Jemison, Lawrence Livermore National Laboratory

Limitless, pollution-free energy is one step closer to becoming a reality. On Dec. 5, 2022, the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory in Livermore, California, conducted a controlled nuclear fusion reaction that produced more energy than it consumed.

Nuclear fusion is the combining of two atomic nuclei to form the nucleus of a heavier element. Fusion reactions between low-mass (light) nuclei release a great amount of energy. Fusion produces the energy of the sun and other stars and the explosive force of thermonuclear weapons.

Nuclear fusion releases large amounts of radiation. Fusion occurs when the nuclei of two lightweight elements join to form the nucleus of a heavier one. In the example shown here, nuclei of deuterium and tritium unite and form a helium nucleus.
Credit: World Book illustration by Mark Swindle

The NIF uses a technique called inertial confinement fusion (ICF). In ICF, several extremely powerful lasers hit a fuel pellet about the size of a pencil eraser. The lasers heat the pellet to millions of degrees, causing the nuclei within it to undergo fusion and release energy. In this experiment, the lasers heated the pellet with 2.05 megajoules of energy and the pellet released 3.5 megajoules. NIF scientists and engineers improved the design of the fuel pellet and increased the power of the lasers to make this breakthrough.

If the NIF experiment produced energy, why can’t the facility simply be rebuilt all over the world to provide unlimited power? Although the reaction produced more energy than the energy in the laser light, the lasers themselves are too inefficient for a power plant. The lasers used hundreds of megajoules to produce those 2.05 megajoules of energy in the form of laser light. Furthermore, NIF can only perform up to 3 shots per day in its current configuration. Scientists and engineers estimate that a similar ICF facility will need to perform 10 shots per second to become profitable.

Where, then, does this leave fusion development? NIF scientists and engineers will work to improve their energy gains through fine-tuning their fuel pellets and laser output. But the facility was never meant to be a power plant. NIF was designed for research, particularly into the effects of nuclear weapons. The Comprehensive Nuclear-Test-Ban Treaty prohibits the testing of nuclear weapons, but with NIF, scientists can mimic the conditions of a nuclear blast to develop more efficient nuclear weapons.

Many environmentalists have an uneasy relationship with fusion, in part due to its connection with nuclear weapons research. Some also think that functional fusion power plants will come too late to help slow the progression of global warming. Even with this breakthrough, experts predict that commercial fusion plants are likely at least 40 years away. People also worry that fusion research is taking resources away from research into grid energy storage and is detracting from such financially viable alternatives as wind and solar power.

But the prospective benefits of fusion are too great to ignore. Limitless, pollution-free energy is closer than it ever has been—even though it’s still pretty far away. What will people do with all that power?

Feb. 14, 2012

Where is the hottest place on Earth? For one brief instant it was in San Mateo, California–or to be more specific, at the Stanford Linear Accelerator Center (SLAC) at Stanford University. The staggering 3.6-million °F (2-million °C) temperature was created by scientists studying a form of plasma created in the massive heat. A plasma is a form of matter that behaves somewhat like a gas but can conduct electricity and reacts to a magnetic field. Scientists sometimes call plasmas the fourth state of matter, after solids, liquids, and gases. The scientists created the extremely intense heat by shooting a powerful beam of X rays at a piece of aluminum foil.

In the solar system, only nuclear explosions and the interior of the sun are hotter than the temperatures created in the SLAC experiment. However, the goal of the experiments was not to create the hottest temperature. Instead, the intense heat was needed to produce a form of plasma commonly called “hot dense matter.” This form of plasma is similar to the plasma that makes up the sun. Scientists believe the study of hot dense matter will help people better understand how the sun works and, possibly, how to produce the same type of matter on Earth on a much larger scale.

Lightning bolts consist of plasma. Few other forms of plasma occur naturally on Earth. © Marco Alegria, Shutterstock

The results of the experiments may help scientists trying to create a controlled fusion reaction on Earth. This reaction is the source of the sun’s enormous power. Scientists are already performing experiments to produce and control fusion. One such experiment is called the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in Livermore, California. There, scientists are using the world’s most powerful laser to create small fusion reactions. In Europe, the ITER experiment is under construction. This is the first large-scale attempt to make a controlled fusion reactor that will produce more power than it uses. Harnessing the power of fusion would revolutionize energy production. Fusion releases tremendous amounts of energy and carries a relatively small risk of environmental pollution.

Additional World Book articles:

• Ion
• Nuclear energy