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Nuclear fusion breakthrough to be tested with world's biggest laser

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The discovery took place in an impossibly small slice of time, less than it takes a beam of light to move an inch. In that small moment, nuclear fusion as an energy source went from a distant dream to reality. The world is now grappling with the implications of the landmark.

For Arthur Pak and countless other scientists who have spent decades getting to this point, the work is just beginning. Pak and his colleagues at Lawrence Livermore National Laboratory are now faced with a daunting task: to do it again, but better – and bigger.

That means perfecting the use of the world’s largest laser, housed in the lab’s National Ignition Facility, which sci-fi fans will recognize from the movie “Star Trek: Into Darkness” when it was used as the backdrop for the Starship’s warp core. Enterprise.

Shortly after 1am on December 5th, the laser fired 192 beams in three carefully modulated pulses into a cylinder containing a tiny diamond capsule filled with hydrogen, in an attempt to trigger the first fusion reaction that produced more energy than was needed. to create it. He did, starting the path toward what scientists hope will one day be a new carbon-free energy source that will allow humans to harness the same source of energy that lights the stars.

Pak, who joined the Lawrence Livermore lab outside San Francisco in 2010, woke up at 3 am that day, unable to resist checking the initial results from his home in San Jose. He tried to stay awake for the injection itself, finally giving up when the experiment’s meticulous preparations dragged on late into the night. “If you stayed awake for every shot, every single time for 10 years, you would go crazy,” he said.

Over the past few months, it had become clear that his team was getting close, and in the pre-dawn darkness, he checked a key number that could show whether they had made it – a count of neutrons produced by the explosion.

“When I saw that number, I was blown away,” he said.

“You can work your entire career and never see this moment. You’re doing this because you believe in fate and you like the challenge,” said Pak, the experiment’s lead diagnostics. “When humans come together and work collectively, we can do amazing things.”

The team at Lawrence Livermore – a government-funded research lab – will likely run their next test in February, with several more experiments in the months to come. The objective will be to continue increasing the amount of energy produced in the reaction. That means more tweaks: use more laser energy. Adjust the laser burst. Generate more x-rays inside the target – a key step in the process – using the same amount of energy. Perhaps eventually upgrading the facility itself, a decision that would require buy-in from the Department of Energy and a large amount of funding.

All of this will take years, if not decades, starting with experiments at the Lawrence Livermore lab that last just nanoseconds.

“We need to figure out: Can we simplify? Can we make this process easier and more repeatable? Can we start doing it more than once a day?” said Kim Budil, director of the Lawrence Livermore laboratory. “Each of them is an incredible scientific and engineering challenge for us.”

Most experts predict that the world is still at least 20 to 30 years away from fusion technology becoming viable on a scale large and affordable enough to produce commercial power. This timeline puts fusion beyond the scope of being significantly used to achieve the world’s net zero emissions targets by 2050. In this sense, fusion may be the carbon-free energy source of the future, but not of the current global energy transition. that we face. continuous obstacles.

Fusion captured the scientific imagination for decades. It is already used to give modern nuclear weapons their devastating power, but the dream is to domesticate it for civilian energy demand. If it can be scaled up, it will lead to power plants that provide abundant electricity day and night without emitting greenhouse gases. And unlike today’s nuclear power, generated through a process called fission, it wouldn’t create long-lived radioactive waste. Entire generations of scientists pursued it. President Joe Biden’s top science adviser, Arati Prabhakar, spent a summer working on the lab’s laser fusion program as a 19-year-old college student in bell-bottoms – in 1978.

“This is a tremendous example of what perseverance can achieve,” she said at a press conference last week. “That’s how you do really big and difficult things.”

merging atoms

The successful laser shot produced fusion reactions generating 3.15 megajoules of energy, surpassing the 2.05 megajoules transmitted by the laser. It was an important threshold, the first time that more energy came out of the laser than came in. But the equation needs to lean much more in the direction of how much comes out to become commercially viable.

While today’s nuclear power plants employ fission, pulling atoms apart, fusion brings atoms together. Fusion researchers have followed two main paths. Lawrence Livermore, using a process called inertial confinement, blasts targets with laser beams, imploding a small amount of hydrogen until it fuses into helium. A commercial power plant using this approach would need to repeat the process several times, extremely quickly, to generate enough energy to feed the electrical grid.

Several companies are developing inertial confinement systems, although there are significant differences. Some are looking for different materials for the target, while others are using particle accelerators instead of lasers, triggering the fusion reaction when the atoms collide.

The main competing idea is called magnetic confinement, with systems that create a cloud of plasma, superheated to hundreds of millions of degrees, that can trigger a fusion reaction. Powerful magnets control the plasma and sustain the reaction. This approach has yet to achieve a net energy gain, and the approach faces challenges, including developing better magnets and creating materials that can withstand superheated temperatures and be used in the vessel to contain the plasma.

To date, about $5 billion in funding has gone to fusion companies, with the vast majority going towards magnetic confinement technologies, according to the Fusion Industry Association trade group.

Inertial confinement may be better suited to prove that fusion can work, said Adam Stein, director of nuclear power innovation at The Breakthrough Institute, a research group based in Oakland, Calif. But in the long term, when it comes to commercialization, “plasma magnetic confinement has a better chance of success,” he said.

‘Be an optimist’

Years have been spent refining every part of the process in the Lawrence Livermore laboratory.

Much of the success has come down to precision. All fuel capsules contain small imperfections that can make a significant difference to how the reaction takes place. As well as the hydrogen frozen inside, a mixture of deuterium and tritium isotopes. The team used to produce the hydrogen ice, melt it and try again several times before a shot, hoping to get the best possible target and increase the chances of success.

Everyone working on fusion “has to be optimistic,” said Denise Hinkel, a physicist who focuses on improving the predictive ability of the program’s computer simulations and has worked at Lawerence Livermore for 30 years. “Otherwise you wouldn’t stay in the field.”

This summer, the giant laser will be able to deliver about 8% more energy than it did during this month’s shoot, according to Jean-Michel Di Nicola, chief laser engineer at the National Ignition Facility. Michael Stadermann, the target fabrication program manager, said the lab is also developing a computer program that can examine fuel capsule casings for flaws much faster than humans can. They are also working with the capsule manufacturer to improve the manufacturing process.

It’s possible that Lawrence Livermore’s discovery will remain just a moment in scientific history and not herald the beginning of a new fusion industry powering the world. Bridging the gap between experiment and commercialization could take decades, if ever. And magnetic confinement may eventually be the fusion method that wins, providing the world with abundant clean energy. Pak, a soft-spoken man with brown hair and a quick wit, said the result would not disappoint him.

“They can learn from us – we can learn from them,” said Pak, 40. “When I’m old, I’ll be very pleased with my contributions.”


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