For the first time on the morning of December 5th, 2022, humans got more power from a fusion reaction than they needed to start it. They put 2.05 mega joules in and got 3.15 mega joules out for a 1.1 net energy gain.
Fusion is not the same as fission, where the energy comes from splitting atoms, as in today’s nuclear reactors and bombs. Instead, a fusion reaction combines the atoms that release the energy, as in stars like the Sun.
Fusion releases prodigious amounts of energy. One joule equals a watt by second; 3.15 mega joules represent enough power to set two gallons of ice to a boil. All that power came from a fuel ball the size of a peppercorn.
The fuel used for the fusion reaction was a combination of deuterium and tritium, two forms of hydrogen, wrapped in diamond and suspended in helium inside a gold cylinder no bigger than a short piece of macaroni, described with the scientific name “hohlraum.”
Lasers entered the top and bottom of the cylinder and hit its inside walls producing X-rays. The radiation eroded (“ablated” is the exact term) the diamond, compressing the fuel inside it until it ignited into a fusion reaction with a “rocket-like” implosion, according to a special report on the experiment by the lasers team at the Lawrence Livermore National Laboratory.
Folks at the Livermore Lab, one hour east of San Francisco over the Oakland Bridge, had done similar experiments 100 times before. On December 5th they were the first humans anywhere to gain energy from fusion.
They announced it on December 13th in an event with the Department of Energy and the National Nuclear Security Administration. A reporter asked Livermore Lab director Dr. Kim Budil why they waited eight days to break the news. “There were a lot of neutrinos,” she said, explaining that they did a peer review of all the experiment’s data before announcing the results.
- 192 high-intensity lasers
- 1 gold cylinder or hohlraum
- Diamond (artificial)
- Precise measuring equipment (abundant)
Schedule some time at the National Ignition Facility in the Lawrence Livermore National Laboratory in California, the only place with enough lasers for this recipe. Prepare a fuel capsule by combining the deuterium and tritium and wrapping the mix in a tiny diamond ball, making sure the surface is completely clear of imperfections (it helps to scan the ball with an electronic microscope).
Suspend the fuel capsule inside a 1-centimeter-tall cylinder made of gold or other high atomic number material (check instructions to get your hohlraum right). Point your laser beams to enter the target through the laser entrance holes at the ends of the cylinder and strike the inside of the hohlraum until it’s hot enough to generate X-rays, about 100 million degrees kelvin.
The capsule needs to ablate in a perfectly symmetrical way so that the extreme pressures and temperatures cause the deuterium and tritium atoms inside to fuse. Measure the output at subatomic level to confirm if you got more energy than you burnt with the lasers.
Hohlraum or tokamak?
They’ve been working on lasers at Livermore Lab for over 60 years, and the National Ignition Facility is one of a kind. Presenters made clear during the announcement on December 13th that it could be decades until we get fusion power plants. To get there, startups are working on another fusion technology which instead of hitting a hohlraum with lasers confines the fuel in a magnetic field inside a donut-shaped device called a “tokamak.”
In either configuration, fusion power plants would help combat climate change because they are a source of renewable energy when compared to the alternatives we use today. Their fuel is hydrogen, which does not produce emissions like fossil fuels, they would leave no long-lasting radioactive waste like nuclear plants, and they would not present the risk of a meltdown.
Reporter Benjy Sarlin of Semafor newsletter asked former U.S. Secretary of Energy and fusion investor Ernest Moniz when we could expect fusion power plants. Moniz told him that he believes that could start happening in the 2030s. Whether by compressing fuel in a hohlraum or by confining it in a tokamak, “otherworldly conditions of high temperature must be not only attained by also reliable sustained for an economically viable power plant,” Moniz said. In any case, he said the Livermore Lab demonstration is a major accomplishment to establish fusion science, a necessary step before any power plant.
See you in 2023
That was all for issue #27 of Verb’s Else newsletter. We’ll be back on January 9th, 2023. Meantime, here’s a little celebratory video to thank you for reading: