In early August, American researchers announced a major breakthrough in nuclear fusion by reaching a power of 10 quadrillion Watts under the action of lasers. A few months earlier, China and South Korea were breaking temperature records. While in Europe, the Iter reactor is at the end of assembly. Nuclear fusion, mimicking the energy of the sun, holds the promise of an unlimited and clean resource.
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On August 8, at the National Ignition Facility (NIF) in California, physicists reached 1.3 megajoules of thermonuclear energy, the power of a car battery. Modest. But, for comparison, the power produced has increased eightfold since the last test in the spring. “The experiment was made possible by focusing the light of 192 lasers – spread over an area the size of three football fields – on a target the size of a human hair’s diameter, generating more than 10 quadrillion watts per fusion, for 100 trillionths of a second (100 billionth of a billionth of a second) “, explains the laboratory in a press release. This technology is called inertial confinement fusion.
With this reaction, the American researchers have almost reached the ignition threshold, that is to say the point where the fusion produces more energy than it took to initiate it and can therefore be self-sustaining. -maintain. “This is the most significant advance in inertial fusion since its inception in 1972,” explains Professor Steven Rose, co-director of the center for research in this field at Imperial College London.
Obtaining a controlled and sustainable nuclear fusion reaction is a holy grail of energy. It is a question of reproducing on Earth the reaction at the origin of the power of the sun where light atoms of hydrogen (the most abundant matter in the Universe) merge to give birth to heavier elements by producing very large amounts of energy, without waste. It is the reverse of nuclear fission (used in power plants today) where heavy nuclei are broken.
Seven times the temperature of the sun
While inertial fusion is progressing, the other path, confinement fusion, is also making great strides. Here, it is a question of maintaining a plasma at very high temperature in a magnetic field (in a Tokamak). Last June in China, engineers at the Experimental Advanced Superconducting Tokamak (EAST) reactor managed to maintain a temperature of 120 million degrees for 101 seconds and even reached 160 million degrees for 20 seconds. A few months earlier, it was South Korea that had managed to maintain a plasma of 100 million degrees for 20 seconds in the Korea Superconducting Tokamak Advanced Research (KSTAR). For comparison, the core of the sun is at 15 million degrees.
In Europe, in Cadarache in particular in the south of France, eyes are on the Iter experimental reactor. Built by the European Union, China, the United States, Russia, Japan, Korea and India, this industrial demonstrator is at the end of assembly. The reactor core, a 23,000-ton jigsaw puzzle, must produce its first plasma in 2025. In July 2020, Emmanuel Macron celebrated this final stage of construction with his partners: “Imagine that the experiment was conclusive, that it could find industrial applications tomorrow! We will have developed a non-polluting, carbon-free, safe and virtually waste-free energy, which will simultaneously meet the needs of all areas of the globe, meet the climate challenge and preserve natural resources”.
Ludovic Dupin @LudovicDupin
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