US government scientists said Wednesday they have made an important step toward making nuclear fusion — the process that powers stars — a viable energy source for mankind.
Using the world’s largest laser, researchers coaxed fusion fuel to heat beyond that heat for the first time, achieving a phenomenon they called a burning plasma, marking a step toward self-sustaining fusion energy. marked.
The energy produced was modest—equivalent to nine nine-volt batteries of the kind that power smoke detectors and other small devices. But the experiments at the Lawrence Livermore National Laboratory Facility in California represented a milestone in the decades-long quest to harness fusion energy, even as researchers caution that more work may be needed for years to come. is required.
The experiments produced self-heating of matter to a plasma state through nuclear fusion, which is the fusion of atomic nuclei to release energy. Plasma is any of various states of matter, along with solid, liquid, and gas.
The National Ignition Facility’s target chamber is seen in an undated handout image at Lawrence Livermore National Laboratory in Livermore, California, US. (Reuters)
“If you want to start a camp fire, you want the fire to be hot enough that the wood itself continues to burn,” said Alex Zilstra, an experimental physicist at Lawrence Livermore National Laboratory — part of the US Department of Energy — and responsible for the lead. Author research published in the journal nature“It’s a nice analogy for a burning plasma, where fusion is now starting to become self-sustaining,” Zillstra said.
The scientists directed 192 laser beams toward a tiny target that consists of a capsule less than a tenth of an inch (about 2 mm) in diameter, filled with a fusion fuel consisting of plasmas of deuterium and tritium – hydrogen atoms. Two isotopes, or forms. At very high temperatures, the nuclei of deuterium and the nuclei of tritium fuse, releasing a neutron and a positively charged particle called an “alpha particle” – consisting of two protons and two neutrons – and energy is released.
“Fusion requires that we get the fuel incredibly hot to burn – just like a regular fire, but for fusion we need about a hundred million degrees[Fahrenheit]. For decades we’ve been heating the fuel a lot. Putting experiments are able to generate a fusion reaction, but this is not enough to produce the net energy from the fusion,” Zilstra said. “Now, for the first time, the fusion reactions taking place in the fuel provided most of the heating – so fusion is beginning to dominate the heating we do. This is a new regime called burning plasma,” Zillstra said.
Unlike the burning of fossil fuels or the fission process of existing nuclear power plants, fusion offers the potential for abundant energy without pollution, radioactive waste or greenhouse gases. Nuclear fission energy comes from splitting atoms. Fusion energy comes from merging atoms together, like the stars inside, including our Sun.
Private sector enterprises – dozens of companies and institutions – are also pursuing a fusion energy future, with some oil companies even investing.
“Fusion energy is the holy grail of clean boundless energy,” said Anne Kricher of Lawrence Livermore National Laboratory, lead designer for the experiments conducted in 2020 and 2021 at the National Ignition Facility and first author of a fellow paper published in the journal Science. nature physics,
In these experiments, fusion produced about 10 times more energy to heat the fuel, but less than 10 percent of the total amount of laser energy because the process remains inefficient, Zylstra said. Critcher said the laser was used in each experiment for only 10 billionths of a second, with fusion output lasting up to 100 trillionths of a second.
Zylstra said he is encouraged by the progress. “Making fusion a reality is a very complex technical challenge, and making it practical and affordable will require serious investment and innovation,” Zillstra said. “I see fusion as a decadal scale challenge for fusion to be a viable source of energy.”
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