On August 8, for an almost imperceptible fraction of a second, massive lasers installed in a government complex in northern California mirrored the operation of the sun on a tiny hot surface, no larger than a human hair. It may seem ridiculous at first glance, but it is an important advance in research on nuclear fusion, a renewable energy seen by its defenders as the solution to the many energy and environmental challenges of our world.
The experiment took place at the National Ignition Facility, which occupies the space of three football fields on the campus of the Lawrence Livermore National Laboratory, on the eastern part of the San Francisco Bay. Powerful lasers were aimed at a tiny target, causing a reaction that gave off more than 10 quadrillion watts of power.
Remarkably, this represents about 6% of the total energy of the sun which constantly reaches the surface of the Earth, while the experiment only lasted 100 trillionths of a second. In that tiny amount of time, the scientists still made a big breakthrough: the hot spot was able to set off a self-sustaining chain reaction, merging other hydrogen atoms and continuing the process of producing energy automatically. , like a combustion engine burning fuel molecule after fuel to keep running.
The ignition threshold in the line of sight
During the experiment, scientists almost reached what is known as the ignition threshold, a key step in the roadmap to a workable fusion. The ignition threshold is when the amount of energy produced as a result of fusion equalizes the amount of energy used to trigger it. The moment when the return becomes positive in sum and brings in energy.
Considering that the ignition threshold is equivalent to an efficiency of 1, the scientists succeeded here in reaching 0.7, equaling the world record achieved in 1997 with the European Tokamak JET. “This phenomenal breakthrough brings us dangerously close to demonstrating a ‘net gain of energy’ from fusion reactions, just when the planet needs it.”, said Arthur Turrell, physicist and author of The Star Builders : Nuclear Fusion and the Race to Power the Planet.
For decades, dozens of installations have experimented with different methods. The Lawrence Livermore National Laboratory reports that, although an analysis of the results has yet to be done by the scientific community, initial data shows energy production eight times higher than experiments carried out earlier in the year and 25 times higher. more than those of 2018. “For comparison, this [représente] about 1000x more energy efficiency than what we got when I joined the project 10 years ago “physicist Jayson Luc Peterson, a member of the team behind the exploit, said on Twitter.
Note that the Tokamak of the international ITER project under construction in the south of France aims for an efficiency of 10 (10 times more energy produced than energy consumed). Unlike inertial confinement fusion used by researchers at Lawrence Livermore National Laboratory, the Tokamaks, these large ring-shaped experimental machines, employ the so-called magnetic confinement method.
The holy grail of energy?
Today, nuclear power plants operate on the principle of nuclear fission, the process of dividing atoms to create energy. On the contrary, fusion consists of fusing hydrogen atoms into helium, like the sun does, releasing a large amount of heat which is then converted into electricity in turbines in the manner of a conventional power station. Fusion is a sort of holy grail for many scientists because in theory it could provide an unlimited source of clean, more secure energy without any release of long-lived radioactive waste.
Note that the National Ignition Facility is not designed as a basic fusion energy development tool, but as a nuclear weapon research tool. According to Jeremy Chittenden, co-director of the Center for Inertial Fusion Studies at Imperial College London, the result should, however, encourage further efforts focused on the creation of clean energy.
“We have now proven that it is possible to achieve ignition, which will give inspiration to other laboratories and start-ups around the world (…) to try to reproduce the same conditions with a simpler, more robust and above all less expensive method. ” In Europe, the ITER project is targeting the 2050s for the first commercial demonstrations, but some private companies intend to go faster, citing first operations by 2030.
Of course, there are still many obstacles in the way. Once the ignition threshold is exceeded, it will be necessary to go much further to compensate for the loss of energy generated by the conversion of heat into electricity. In addition, the reaction created by the researchers will have to be reproduced several dozen times per second and continuously.
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