Scientists have finally managed to bottle the sun.
Researchers at the National Ignition Facility in Livermore, California, have ignited controlled fusion, which produces net energy. The long-awaited achievement, to be announced by U.S. Department of Energy officials on Dec. 13, is the first time the lab has been able to recreate reactions in the sun in a way that causes the experiment to produce more energy than goes in.
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“This is a huge breakthrough,” says Gilbert Collins, a physicist at the University of Rochester in New York, a former collaborator at NIF but not involved in the research that led to the latest advance. “Since I’ve been in the field, fusion has always been 50 years away…. With this achievement, things change.”
Nuclear fusion has the potential to provide a clean energy source. Fission reactors, used to generate nuclear energy, rely on heavy atoms such as uranium to release energy as they break down into lighter atoms, including some that are radioactive. While generating energy through fission is relatively easy, dealing with residual radioactive debris that could remain dangerous for hundreds of years is an environmental nightmare.
Controlled fusion, on the other hand, would not produce such long-lived radioactive waste, but would be technically more difficult to achieve in the first place. In nuclear fusion, light atoms fuse together to create heavier atoms. In the sun, this usually happens when protons (the nuclei of hydrogen atoms) combine with other protons to form helium.
Getting the atoms to fuse requires a combination of high pressure and high temperature, squeezing the atoms tightly together. Strong gravity does most of the work in the sun.
In the National Ignition Facility, 192 laser beams directed at a small patch of fuel provide a burst of energy that does the trick. The result, says Carolyn Kuranz, a physicist at the University of Michigan in Ann Arbor, is a burst of fusion energy that, though brief, is more powerful than the laser energy that sparked the reaction. He was not involved in the study.While the total energy released by the experiment has not been made public, it exceeds the 1.3 million joules produced by earlier NIF experiments, which marked The team managed to ignite nuclear fusion for the first time (Number: 21/8/18).
But this latest fusion burst still doesn’t produce enough power to run the NIF experiment’s laser power supply and other systems.
“The net energy gain is related to the energy of the light that hits the target, not the energy that produces the light,” said University of Rochester physicist Riccardo Betti, who was also not involved in the research. “It’s now up to scientists and engineers to see if we can translate these physical principles into useful energy.”
Still, it’s a potential technological tipping point, comparable to the invention of the transistor or the first flight of the Wright brothers, Collins said. “We now have a laboratory system that we can use as a compass on how to make rapid progress,” he said.