We now have a true fusion energy breakthrough

Researchers at the National Ignition Facility in Livermore, Calif., home to the world’s most powerful laser, announced Tuesday that they have crossed a tipping point in their quest for fusion power.

This is 1) a major scientific breakthrough and 2) we still have a long way to go to harness the reaction that powers the Sun, nuclear fusion, as a viable source of abundant clean energy. On December 5, the team fired 192 laser beams at small fuel pellets, producing slightly more energy than the lasers put in. Nuclear Security Administration, at a news conference on Tuesday.

To make fusion capable of actually producing electricity for the grid, we can’t just cross the ignition finish line. that should blow it away. While this announcement is an important incremental step forward, the breakthrough is far from usable. NIF itself is a research institute, so its technology is not intended for power generation. Therefore, designing a fusion reactor that utilizes this new approach presents itself as an engineering challenge.

NIF is part of the Lawrence Livermore National Laboratory operated by the US Department of Energy. Energy Secretary Jennifer Granholm said on Tuesday, “This is where America leads, and we’re just getting started.

The Financial Times first revealed on Sunday that a breakthrough fusion announcement is imminent.

Nuclear fusion is the reaction of small atomic nuclei such as hydrogen and helium colliding and sticking together to generate enormous amounts of heat, which could theoretically be used to make electricity. This is in contrast to the fission reaction used in conventional nuclear power plants. In nuclear fission reactions, large atoms like uranium are split up. The problem with nuclear fusion is that the nuclei are positively charged and therefore repel each other. In order for them to overcome their opposition, they must move very fast in the confined space, creating a high-energy state of matter known as plasma.

Scientists have struggled for decades to do this. He has two main approaches. One is NIF’s strategy of compressing small pellets of fuel with a powerful laser. Another method is to heat the plasma to a temperature higher than that of the Sun and confine it with a magnet. This is how ITER, the world’s largest fusion project, currently under construction in the south of France, generates reactions.

The Sun and other stars are able to pull this off because they have enough matter to generate enormous gravitational forces. This is because it creates a nuclear fusion reaction that accelerates and confines atoms to produce light and heat that can be experienced from millions of miles away.

Here on Earth, humans have practically known how to produce nuclear fusion since 1952 — with thermonuclear weapons. Scientists have been able to perform nuclear fusion in the laboratory, but it only occurs intermittently and requires a great deal of energy consumption. Imagine using a blow torch to light a match. .

In 1997, the National Academy of Sciences established Ignition as the goalpost for fusion at NIF. It defined ignition as “gain greater than 1”. This means that the fuel target puts out more energy than the amount of laser energy hitting the fuel target.

For months, NIF scientists have been intriguingly close. About a year ago they said they were about 70% of the way there. NIF plasma physicist Tammy Ma told his Vox in January 2022:

Now they have crossed that line.

University of Michigan plasma physicist Carolyn Kuranz said in an email.

Umair Irfan/Vox

Troy Carter, a plasma physicist at the University of California, Los Angeles, explained that while NIF has made significant breakthroughs, it falls short of what is needed. As noted by the National Academy of Sciences, the key metric is the fusion energy gain factor, also known as ‘Q’. It is the ratio of power used to start and sustain a fusion reaction compared to the power produced. A gain of 1 means that the response is balanced. The latest announcement at NIF shows an increase of about 1.5. This means that the reaction has become energetically positive.

But only if we narrowly define the energy input to be the laser energy striking the fuel target. Measured from the total amount of energy required to charge and fire the laser, it is about 300 megajoules, and recent results are still far short. A gain of 100 or more is needed to actually produce more energy from fusion than the laser requires from the power grid.

Another limitation is that the NIF can only fire a few laser shots per day. Also, the amount of power required can cause power outages in the lab. About 10 shots per second are required to run a real fusion reactor.

The fuel itself may also burn more efficiently. “The NIF shot burned only a fraction of the fuel in the capsule,” Carter said in an email. “If you can find a way to burn more fuel, the gains go up significantly.”

That requires tweaking the tiny fuel pellets to direct more laser energy into atom compaction.

When it comes to lasers, NIF uses outdated technology and has a lot of room for improvement. Lasers are only about 1% efficient at converting electricity into laser light, but modern designs give him 20% efficiency. “NIF builds on his 1980s laser technology,” said Kim Budill, Director of Lawrence Livermore National Laboratory, at a press conference.

Still, achieving ignition is an important milestone and an important signal that scientists are on the right track. Carter said, “It justifies an aggressive push to develop and deploy fusion energy as soon as possible in hopes of impacting climate change!”

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