A 2021 Breakthrough In Fusion Power Is Being Celebrated In Three New Studies But Controversy Remains Over Replicating The Findings.

The fusion power experiment, conducted by the National Ignition Laboratory at Lawrence Livermore National Laboratory in California, is explored in detail in three new papers — one published in Physical Review Letters and two published in Physical Review E — that claim the researchers achieved “ignition ,” a critical step that proves that controlled nuclear fusion is possible. But definitions of what constitutes an ‘ignition’ vary, and however defined, the 2021 results are far from a practical fusion reactor, despite the fact that it produces a lot large amount of energy. Nuclear fusion involves fusing two elements, typically isotopes of hydrogen, into the heavier element helium. It releases vast amounts of energy in the process, which is the process that powers stars like the Sun. A fusion power plant would produce plenty of energy using only hydrogen from water as fuel and producing helium as waste, without the risk of meltdown or radiation. This contrasts with nuclear fission, the type of reaction in modern nuclear power plants, which splits the nuclei of heavy elements such as uranium to produce energy. While fusion reactions occur in the Sun and uncontrolled fusion occurs in thermonuclear weapon explosions, controlling a sustained fusion reaction to produce energy has eluded nuclear engineers for decades. Experiments of various designs have been able to produce fusion reactions for very short periods of time, but they have never reached “ignition,” the point where the energy released by a fusion reaction is greater than the amount of energy required to create and sustain it. reaction. The team at the National Ignition Facility and the authors of one of the three new papers, this one published in the journal Physical Review Letters, argue that “ignition is a state where the fusion plasma can begin to ‘burn spread’ into the surrounding cold fuel, allowing for the possibility of high energy gain.” That is, fusion started in cold hydrogen fuel and the reaction was scaled up to produce much more power than in previous experiments. The Aug. 8, 2021, experiment required 1.9 megajoules of energy in the form of an ultraviolet laser to trigger a fusion reaction in a small, frozen globule of hydrogen isotopes — a design for inertial confinement fusion — and released 1.3 megajoules of energy, or about 70 % of the energy given in the experiment. The power, in other words, was more than a quadrillion watts of power, even if it was only released for a fraction of a second. “The record setting was a major scientific advance in fusion research, proving that laboratory fusion ignition is possible at NIF,” Omar Hurricane, chief scientist for Lawrence Livermore National Laboratory’s inertial fusion program, said in a statement. “Achieving the conditions required for ignition has been a long-standing goal for all confinement inertial fusion research and opens access to a new experimental regime where alpha particle self-heating overcomes all cooling mechanisms in the fusion plasma.” Later attempts to replicate the experiment produced much less energy output, most in the 400 to 700 kilojoules range, leading some researchers to suggest that the National Ignition Facility’s experimental design is a technical dead end, according to news section reports in the journal Nature. “I think they should call it a success and call it quits,” physicist and former US Naval Laboratory laser fusion researcher Stephen Bodner told Nature. The National Ignition Facility cost $3.5 billion, more than $2 billion more than expected, and has been delayed, with researchers initially targeting 2012 as a deadline to prove ignition was possible using the design. The new studies show that researchers are eager to continue exploring what the National Ignition Facility can do, especially because unlike other fusion researchers, the facility’s researchers are not primarily focused on developing fusion power plants, but on better understanding the thermonuclear weapons. “We have been operating in a regime that no researcher has had access to since the end of the nuclear tests,” Dr. Harrigan said. “It’s an incredible opportunity to expand our knowledge as we continue to make progress.”