Scientists in the United States have achieved net energy gain in a fusion reaction for the second time since December in efforts to find a clean source of energy, according to the Lawrence Livermore National Laboratory.
Scientists at the California-based lab repeated the fusion ignition breakthrough in an experiment in the National Ignition Facility (NIF) on July 30 that produced a higher energy yield than in December, a Lawrence Livermore spokesperson said on Sunday.
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Final results are still being analysed, the spokesperson added.
Nuclear fusion reaction involves combining two atomic nuclei to form a single heavier one, releasing an enormous amount of energy. Scientists have known for about a century that fusion powers the sun and have pursued developing fusion on Earth for decades, as they look for limitless clean and safe source of power to help curb climate change.
If technology around fusion reaction is further advanced, it can be used to produce power at an industrial scale.
The US Energy Department called it “a major scientific breakthrough decades in the making that will pave the way for advancements in national defence and the future of clean power”.
The scientists focused a laser on a target of fuel to fuse two light atoms into a denser one, releasing the energy.
That experiment briefly achieved what is known as fusion ignition by generating 3.15 megajoules of energy output after the laser delivered 2.05 megajoules to the target, the Energy Department said.
In other words, it produced more energy from fusion than the laser energy used to drive it, the department said.
Nuclear scientists outside the lab said the achievement will be a major stepping stone, but there is much more science to be done before fusion becomes commercially viable.
“I am excited. And I do think that fusion is going to play a big role in our energy future,” Troy Carter, a physics professor at the University of California, Los Angeles, told Reuters.