Exclusive: The laser fusion facility goes back to the drawing board

American scientists are rethinking their options after failing to carry out a record-breaking experiment in 2021.

Almost a year ago, scientists working at the world’s largest laser fusion facility announced a remarkable achievement: the facility had broken all records and produced, albeit for just a fraction of a second, a vigorous fusion reaction of the kind that powers stars and fusion weapons. However, the attempt is widely considered a failure. Nature has learned that earlier this year, researchers in California changed course, rethinking their experimental design.

The turn of events has renewed debate about the future of the National Ignition Facility (NIF), a $3.5 billion facility housed at Lawrence Livermore National Laboratory and overseen by the National Nuclear Security Administration (NNSA), the branch of the U.S. Department of Energy that manages nuclear weapons. NIF's primary mission is to create high-yield fusion reactions and inform the maintenance of the U.S. weapons stockpile.

By some measures, the record-breaking laser burst on August 8, 2021, proved that the facility, which cost far more and produced far less than originally promised, had finally accomplished its primary mission. But repeated attempts have yielded, at best, 50% of the energy produced late last year. The researchers didn’t expect everything to go smoothly as they tried to repeat the experiment, as the massive device is now operating at the “ignition” edge of fusion, where small, unintended differences from one experiment to the next can have a huge impact on output. However, for many, the failure to replicate last August’s experiment highlights researchers’ inability to understand, design, and predict experiments at these energies with precision.

Translation from English: Iliana Dechkova

Source: nature.com

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