A scientific institute in the United States is about to make a breakthrough in nuclear fusion research.
The National Ignition Facility (NIF) in Livermore, California, uses a powerful laser to heat and compress hydrogen fuel and is one step closer to achieving massive nuclear fusion.
From an experiment conducted in August 2021, the lab will soon reach its “ignition” goal, 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 byproduct of the splitting 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 source of clean and unlimited 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 concern that the method generates in terms of security and weapons proliferation.
In a process called inertial nuclear fusion, 192 laser beams from the NIF facility – the world’s highest concentration of energy – are directed 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 yielded 1.35 megajoules of energy — about 70 percent 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 NIF, told BBC News.
This month’s experiment achieved a result eight times higher than the previous record (earlier this year) and 25 times the productivity of the experiments conducted in 2018.
said Jeremy Chittenden, co-director of the Center for Inertial Fusion Studies at Imperial College London, in England.
NIF scientists also believe they’ve achieved something called “plasma burning,” in which fusion reactions themselves give off heat for further fusion. This is vital to make the process self-sufficient and highly productive.
“We think our experiment has reached this point, but we’re still analyzing and simulating to make sure we understand the outcome,” Debbie Callahan explains.
After that, the tests will be performed again.
“This is 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 strides, Chittenden said there is still a lot to overcome.
“The megajoules of energy released in the experiment are really impressive in terms of fusion, but in practice this is equivalent to the energy needed to boil a kettle.”
“Much higher fusion energies can be achieved through ignition if we can figure out how to keep the fuel together for longer, making more of it burn.”
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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 laser power 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 divide their time with experiments aimed at national security.
This is one of several projects around the world focusing on fusion research. One of them is the ITER facility, with a budget of billions of euros and is currently under construction in Cadarache, France.
ITER will take a different approach to NIF laser fusion; The facility in southern 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 providing grid power will require another giant leap.
“Converting this concept to a renewable source of electrical energy is likely to be a lengthy process and will involve overcoming significant technical challenges, such as being able to recreate this experiment multiple times per second to produce a stable source of energy,” Chittenden notes.
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