A scientific institute in the United States is on the verge of making a breakthrough in nuclear fusion research.
The National Ignition Facility (NIF) in Livermore, Calif., Uses a powerful laser to heat and compress fuel hydrogen and is one step closer to achieving massive nuclear fusion.
From an experiment carried out in August 2021, the laboratory will soon reach its “ignition” objective, when the energy emitted by fusion exceeds that emitted by a laser.
Fusion is a type of nuclear energy that differs from the fission process, which has been used since 1950 in atomic power reactors. In fusion, energy is generated from the union of atoms, while in fission, it is a by-product of the division of atoms.
Fusion is the same process that occurs in the sun, requires extreme heat and pressure, and is much more difficult to control than fission. However, once mastered, it can provide us with a clean and unlimited source of energy.
The process does not generate the radioactive waste produced by fission reactors, which is one of the major obstacles to the use of nuclear energy today, in addition to the cost and worry that the process generates. in terms of security and proliferation of weapons.
In a process called inertial nuclear fusion, 192 laser beams from the NIF facility – the highest concentration of energy in the world – are aimed at a capsule the size of a pepper.
This capsule contains deuterium and tritium, two different forms of the element hydrogen.
The procedure compresses the fuel to 100 times the density of lead and heats it to 100 million degrees Celsius – hotter than the center of the Sun. These conditions help initiate thermonuclear fusion.
An experiment conducted on August 8 produced 1.35 megajoules of energy, or about 70% of the laser energy that reaches the fuel capsule. Achieving ignition means obtaining a fusion efficiency greater than the 1.9 MJ applied by the laser.
“This is a huge step forward for fusion research and for society as a whole,” Debbie Callahan, a physicist at Lawrence Livermore National Laboratory, which includes the NIF, told BBC News.
This month’s experiment achieved a result eight times the previous record (earlier this year) and 25 times the productivity of experiments conducted in 2018.
said Jeremy Chittenden, co-director of the Center for Inertial Fusion Studies at Imperial College London, England.
Scientists at NIF also believe they’ve done something called “plasma burning,” in which the fusion reactions themselves give off heat for further fusion. This is essential to make the process self-sufficient and highly productive.
“We think our experiment has reached this point, but we continue to analyze and simulate to make sure we understand the outcome,” says Debbie Callahan.
After that, the tests will be performed again.
“It’s fundamental to experimental science,” Callahan says. “We need to understand how reproducible the results are and how sensitive they are to small changes. ”
“Then we have plans to improve the design of this system. We will start working on it next year.
Despite the huge progress, Chittenden said there is still a lot to overcome.
“The megajoules of energy released in the experiment are really impressive in terms of melting, but in practice this equates to the energy required to boil a kettle.”
“Much higher fusion energies can be achieved with ignition if we can find a way to keep the fuel together longer, by making it burn more.”
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Construction of the National Ignition Facility (NIF) in the United States began in 1997 and was completed in 2009. The first trials to test the power of the laser began in October 2010.
Another function of the NIF is to monitor the status and security of nuclear weapons stockpiles in the United States. Sometimes scientists who need to use massive lasers for fusion have to share their time with experiments aimed at national security.
This is one of many projects around the world focused on fusion research. One of these is the ITER facility, with a budget of several billion euros and currently under construction in Cadarache, France.
ITER will take a different approach to NIF laser fusion; The facility in the south of France will use magnetic fields to contain hot plasma, an electrically charged gas. This concept is known as magnetic confinement fusion.
But building commercially viable fusion facilities capable of supplying electricity to the grid will require another giant leap.
“Converting this concept into a renewable electric power source is likely to be a long process and will involve overcoming significant technical challenges, such as being able to recreate this experience multiple times per second to produce a stable power source,” Chittenden notes.
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