We have a real breakthrough in fusion energy

Adriana Lima
By Adriana Lima 9 Min Read

Researchers at the National Ignition Facility in Livermore, Calif., home to the world’s most powerful laser, announced Tuesday that they had passed the critical threshold in their quest for fusion power: getting more energy out of the reaction than they input.

This is 1) a huge scientific advance and 2) still a very, very (long) way to harnessing fusion, the reaction that powers the sun, as a viable source of abundant clean energy. On Dec. 5, the team fired 192 laser beams at a tiny fuel pellet, producing slightly more energy than the lasers put in, “about 2 megajoules in, about 3 megajoules out,” he said. Marvin Adamsdeputy administrator for defense programs at the National Nuclear Security Administration, at a news conference on Tuesday.

To make fusion something that could actually produce electricity for the power grid, it can’t just pass the ignition milestone; must overcome it. This announcement is a major incremental advance, but the breakthrough doesn’t go far enough to be of practical use. Since NIF itself is a research laboratory, its technology is not intended to produce energy. So designing a fusion reactor to take advantage of this new approach will be its own engineering challenge.

NIF is part of the Lawrence Livermore National Laboratory, operated by the US Department of Energy. “This is what it looks like for America to lead, and we’re just getting started,” Energy Secretary Jennifer Granholm said Tuesday.

The Financial Times revealed for the first time on Sunday that a breakthrough announcement on the merger was imminent.

Nuclear fusion refers to the reaction in which the nuclei of tiny atoms like hydrogen and helium collide and combine, generating immense heat, which could, in theory, be used to make electricity. This is in contrast to the fission reaction used in conventional nuclear power plants, where large atoms such as uranium are split apart. The problem with fusion is that the nuclei are positively charged and therefore repel each other. To get them past their opposition, you have to make them move very, very fast in a confined space and create a high-energy state of matter known as plasma.

Scientists have struggled for decades to do this. There are two main approaches: One is to compress a tiny pellet of fuel with powerful lasers, which is the strategy of the NIF. The other is to heat the plasma to temperatures hotter than the sun and contain it with magnets. This is how ITERthe largest fusion project in the world, currently under construction in southern France, will generate the reaction.

The sun and other stars can do this because they have enough matter to generate immense gravity, which accelerates and confines atoms to create fusion reactions that produce the light and heat we can experience millions of miles away.

Here on Earth, humanity has actually known how to produce fusion since 1952, in thermonuclear weapons. Scientists have also been able to produce fusion in laboratories, but only intermittently and with great energy expenditure: Imagine using a blowtorch to strike a match. Slow progress in the pursuit of fusion has also made it difficult to obtain adequate research funding, which in turn has hampered progress.

In 1997 the National Academy of Sciences established Ignition as a target for fusion at the NIF. He defined ignition as “gain greater than unity,” meaning more energy from the fuel target than the amount of laser energy hitting it.

For months, NIF scientists have gotten tantalizingly close. About a year ago, they said they were about 70% there. “We are on the threshold of ignition” Tammy Maa plasma physicist at NIF, he told Vox in January 2022.

Now they’ve crossed that line.

“This result clearly surpasses that mark leaving no doubt that they achieved fusion ignition in the lab,” he said Carolyn Kuranza plasma physicist at the University of Michigan, in an email.

A researcher holds a fusion fuel target

NIF fires powerful lasers at a tiny pellet of hydrogen to trigger a fusion reaction. Umair Irfan/Vox

Slut Carter, a plasma physicist at the University of California at Los Angeles, explained that while NIF has achieved a huge breakthrough, it’s still short of what’s needed. As the National Academy of Sciences has pointed out, the key metric is the fusion energy gain factor, also called “Q.” This is the ratio of the power used to start and maintain a fusion reaction to the power produced. A gain of 1 means that the reaction broke even. The latest announcement at the NIF shows a gain of around 1.5, meaning the reaction has turned energetically positive.

But that’s only if you define the energy input strictly to the energy of the laser hitting the fuel target. When measured by the total amount of energy required to charge and fire the laser, about 300 megajoules, recent results are still very short. To actually produce more energy from the fusion than the laser requires from the electrical grid, you’d need a gain of 100 or more.

Another limitation is that NIF can only fire a few laser shots per day and the amount of electricity required can sometimes cause blackouts in the lab. To operate a real fusion reactor, you would need to fire about 10 rounds per second.

The fuel itself could also burn more efficiently. “NIF’s shot only burned a small fraction of the fuel in the capsule,” Carter said in an email. “If you can find a way to burn more fuel, the gain increases dramatically.”

This will involve optimizing the tiny fuel pellet to get more laser energy directed towards compressing the atoms.

As for the laser, NIF uses an outdated technology that has a lot of room for improvement. Lasers are only about 1% efficient in terms of turning electricity into laser light, while more modern designs can be 20% efficient. “NIF is built on laser technology from the 1980s,” he said Kim woke updirector of Lawrence Livermore National Laboratory, during a press conference.

However, achieving ignition is a major milestone and an important signal that scientists are on the right track. Carter said it “provides greater justification for an aggressive push to develop and deploy fusion energy as rapidly as possible, with the hopes of having an impact on climate change!”

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Target room at the National Ignition Facility

Researchers at Lawrence Livermore National Laboratory’s National Ignition Facility have announced that they have achieved ignition for fusion.Umair Irfan/Vox

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