American scientists confirm a “major breakthrough” in nuclear fusion | Nuclear Energy

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Scientists have confirmed that a major breakthrough has been achieved that could pave the way for future abundance of clean energy after more than half a century of research in nuclear fusion.

Researchers at the US National Ignition Facility in California said fusion experiments released more energy than was pumped out by the lab’s massive high-energy lasers, a landmark achievement known as ignition or energy gain.

The technology is far from ready to turn into viable power plants — and it’s not on the verge of solving the climate crisis — but scientists have hailed the breakthrough as proof that the power of the stars can be harnessed on Earth.

“Last week…they fired a bunch of lasers at a pellet of fuel and more energy was released from that fusion ignition than laser energy was emitted at the White House,” said Dr. Arati Prabhakar, director of policy in the White House Office of Science and Technology. This is a great example of what can be done. That perseverance really pays off.”

Fusion energy raises the prospect of abundant clean energy: the reactions release no greenhouse gases and no radioactive waste. One kilogram of fusion fuel, which is made up of heavy forms of hydrogen called deuterium and tritium, provides energy equivalent to 10 million kilograms of fossil fuels. But it took 70 years to get to this point.

Speaking at Tuesday’s announcement, Jill Hruby, of the National Nuclear Security Administration (NNSA), said the United States has “taken the first tentative step toward a clean energy source that has the potential to revolutionize the world.”

The National Ignition Facility is a huge complex at Lawrence Livermore National Laboratory, near San Jose. It was built to conduct experiments that recreate, briefly and in miniature, the processes launched inside nuclear bombs, enabling the United States to maintain its nuclear warheads without the need for nuclear tests.

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But experiences are also a stepping stone to the clean power of fusion. To achieve the interactions, the researchers fired up to 192 giant lasers into a centimeter-long golden cylinder called a hohlraum. The intense energy heats the container to more than 3mC — hotter than the surface of the Sun — and bathes a peppercorn-sized fuel pellet inside in X-rays.

X-rays strip the surface of grain and trigger a rocket-like implosion, pushing temperatures and pressures to extremes seen only inside stars, giant planets, and nuclear detonations. The implosion reaches speeds of up to 400 kilometers per second and results in the fusion of deuterium and tritium.

Each pair of fused hydrogen nuclei produces a lighter helium nucleus, a burst of energy according to Einstein’s equation E=mc2. Deuterium is easily extracted from seawater, while tritium can be synthesized from lithium found in the earth’s crust.

In the latest experiment, the researchers pumped in 2.05 megajoules of laser energy and got about 3.15 megajoules—an increase of nearly 50% and a sign that fusion reactions in the grains lead to more fusion reactions. “It took less time to produce energy than it takes light to travel an inch,” said Dr. Marvin Adams, of NNSA.

Nuclear scientist Marv Adams explains the successful fusion experiment – video

However, enormous hurdles remain in the search for fusion power plants. While the pellet fired more energy than the laser entered, the calculation does not include the 300 megajoules or so needed to power the laser in the first place. The NIF laser fires about once a day, but the power plant would need to heat targets 10 times a second. Then there are the cost goals. Those used in the American experiment cost tens of thousands of dollars, but for a viable power plant it needed to cost a penny. Another issue is how the energy is released as heat.

With enough investment, “a few decades of research can put us in a position to build a power plant,” said Dr. Kim Podell, director of the Lawrence Livermore National Laboratory. It added that a power plant based on the alternative technology used at Joint European Toros (JET) in Oxfordshire could be ready soon.

“In some ways everything changes; in another case, nothing changes,” said Justin Wark, Professor of Physics at the University of Oxford and Director of the Oxford Center for High Energy Density Science. This result proves what most physicists have always believed — fusion in the laboratory is possible. However, the hurdles that must be overcome to make anything like a commercial reactor are huge, and they should not be underestimated.”

Asking how long it would take to overcome challenges, he said, is like asking the Wright brothers how long it would take to build an airplane to cross the Atlantic right after their first flight. “I understand that everyone wants to think of this as the perfect solution to the energy crisis. It is not, and whoever said it with any certainty is misguided.

“It is very unlikely that the merger will have an impact on a timescale that is short enough to affect the current climate change crisis, so we must not slacken our efforts in this regard.

The latest results also show that basic science works – the laws of physics do not prevent us from achieving the goal – the problems are technical and economic. As Niels Bohr, the Nobel Prize-winning atomic physicist once said: “Prediction is very difficult, especially when it comes to the future.”

Dr Mark Weinman, Reader of Nuclear Materials at Imperial College London, called the achievement “a remarkable scientific achievement – something we haven’t achieved in 70 years of trying”. But he said, “There are still challenges with how to get energy out of the system, how do you conserve energy long enough for it to be useful, how to increase that energy, and whether energy can be cheap enough to compete with other sources.”

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