It’s a major announcement from the scientists of EUROfusion, the European consortium bringing together research on nuclear fusion in Europe, which fell on February 9. Physicists working on the Joint European Torus (JET), an experimental fusion reactor located in the United Kingdom, announce that they have managed to produce 59 megajoules (MJ) of energy from the fusion of atomic nuclei, breaking a record set in 1997.
It is not so much this result that constitutes the interest of this performance but rather the way: the energy was produced in a stable and controlled way, what is more in an experimental device very similar to that which will be at the heart of the experiments of ITER, the international reactor under construction in the Bouches-du-Rhône, which should build a bridge between current experimental devices and future industrial demonstrators.
“A sustained discharge of deuterium-tritium fusion at this level of power – on a near-industrial scale – brings resounding confirmation to all involved in the global quest for fusion. said ITER Director General Bernard Bigot. Fifty-nine megajoules (produced in five seconds), this corresponds to the energy provided by the combustion of 2 kilograms of coal. Difficult to heat the cottages with this. But it only took 0.1 milligrams of tritium and 0.07 milligrams of deuterium, the two elements that make up the fuel, to produce those 59 MJ.
Study the behavior of plasma
The JET is a tokamak, named after the large donut-shaped chamber in which the fuel is confined in the form of plasma, a hot and chaotic state of matter made up of ionized gases. Heated to around 150 million degrees, or ten times the temperature at the core of the Sun, the atomic nuclei of deuterium and tritium acquire such kinetic energy that they can fuse during a collision, the reaction producing a neutron and a helium 4 atom (also called alpha particle), both vectors of high energies which must then be converted into electricity.
Between 1997 and the new experimental campaign carried out in August 2021, the JET went from 16 megawatts (MW) for 0.15 seconds to a peak of around 10 MW but for 5 seconds. For Jeronimo Garcia, from the Magnetic Confinement Fusion Research Institute of the French Alternative Energies and Atomic Energy Commission (CEA), “These results go in the right direction because, at ITER, the plasmas will have to be confined for about 1,000 seconds”. According to EUROfusion, this should not pose a problem: unlike the JET, ITER will benefit from superconducting magnets capable of operating continuously.
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