US to announce 'major breakthrough' in nuclear fusion

Scientists at a federal nuclear weapons facility have made a potentially significant advance in fusion research that could lead to a source of bountiful energy in the future, according to a government official.

The advance is expected to be announced Tuesday by the Department of Energy, which said a “major scientific breakthrough” was made at Lawrence Livermore National Laboratory in California. Jennifer Granholm, the energy secretary, and White House and other Energy Department officials are expected to be in attendance. The Financial Times reported Sunday that the scientific advance involves the National Ignition Facility, or NIF, which uses giant lasers to create conditions that briefly mimic the explosions of nuclear weapons.

The government official, who spoke anonymously to discuss results that are not yet public, said that the fusion experiment at NIF achieved what is known as ignition, where the fusion energy generated equals the laser energy that started the reaction. Ignition is also called energy gain of one.

A scientist familiar with the results who spoke anonymously for the same reason also confirmed that NIF has achieved ignition.

Such a development would improve the ability of the United States to maintain its nuclear weapons without nuclear testing and could set the stage for future progress that could one day lead to the use of laser fusion as a source of carbon-free energy source.

Fusion that could be produced in a controlled fashion on Earth could mean an energy source that does not produce greenhouse gases like coal and oil, or dangerous, long-lived radioactive waste, as current nuclear power plants do.

Most fusion efforts to date have employed doughnut-shaped reactors known as tokamaks. Within the reactors, hydrogen gas is heated to temperatures hot enough that the electrons are stripped away from the hydrogen nuclei, creating what is known as a plasma. Magnetic fields trap the plasma within the doughnut shape, and the nuclei fuse together, releasing energy in the form of neutrons flying outward.

Tuesday’s announcement, however, involves a different approach. NIF consists of 192 gigantic lasers, which fire simultaneously at a metal cylinder about the size of a pencil eraser. The cylinder, heated to some 5.4 million degrees Fahrenheit, vaporizes, generating an implosion of X-rays, which in turn heats and compresses a BB-size pellet of frozen deuterium and tritium, two heavier forms of hydrogen. The implosion fuses the hydrogen into helium, creating fusion.

This article originally appeared in The New York Times.