And the results are even more spectacular.

• In December of 2022, Lawrence Livermore National Laboratory achieved ignition, meaning that scientists successfully created a fusion reaction that produced more energy than it took in.
• Now, eight months later, the same laboratory has reproduced the experiment—only this time, with even better energy results.
• We currently don’t know how much excess energy the reaction produced, but a spokesperson says tha the lab will report the results at “scientific conferences and in peer-reviewed publications.”

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On December 5, 2022, scientists at the Lawrence Livermore National Laboratory (LLNL) achieved something truly remarkable. After firing 192 lasers at a small pellet filled with deuterium-tritium fuel, the resulting reaction essentially created a tiny star for a few nanoseconds. Crucially, the energy created by this reaction was more than the energy put into the reaction. In other words, science had finally achieved nuclear fusion ignition.

Until that point, humans had never been able to recreate the life-giving power generated in the center of our Sun on Earth. But for the first time, the clean energy promise of nuclear fusion—arguably the greatest energy source imaginable—suddenly seemed possible. Now, fast forward only eight months, and LLNL has achieved ignition again. But this time, they had even greater results.

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LLNL spokesperson Paul Rhien spoke with The Financial Times on Sunday, and said that “in an experiment conducted on July 30, we repeated ignition at NIF. Analysis of those results is underway, but we can confirm the experiment produced a higher yield than the December test.”

Although we don’t know the exact amount of energy gained (the December experiment got 3.15 megajoules (MJ) out after putting 2.05 MJ of energy put in), Rhein goes on to say that the lab fully intends to report the results “at upcoming scientific conferences and in peer-reviewed publications.”

LLNL pulled off this second ignition using what’s known as an “inertial confinement” reactor, a kind of fusion reactor that relies on the inertial implosion of the fuel pellet to sustain a reaction. This works in stark contrast to other fusion reactor designs, specifically tokamaks and stellarators, that use a complicated array of superconducting electromagnets to contain super-hot plasma many times hotter than the sun.

In LLNL’s inertial confinement reaction, 192 lasers—fired from a complicated series of laser banks and power amplifiers—converged and superheated a capsule called a hohlraum. This created an X-ray bath that squeezed the deuterium-tritium pellet inside. The pellet then collapsed so quickly that a fusion reaction took place before the fuel could fully disassemble (hence inertial confinement), and for only 100 trillionths of a second, a star was born.

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Now that LLNL has reliably recreated their first experiment—this time, reportedly with even better energy results—it’s clear that inertial confinement is a reliable way to achieve ignition. However, this technique does come with some downsides. Because inertial confinement doesn’t need to contain any superhot plasma, it’s easier to achieve this initial ignition. But it’s another thing entirely to make some sort of inertial confinement energy plant. For one, LLNL’s lasers need to cool down for hours before taking another shot, something that can be improved with more modern laser diodes, but is still a far cry from the many explosions a second that’d need to take place for such an energy source to be economically viable.

But reliably achieving ignition is a huge breakthrough, allowing scientists to continue to learn about the complicated physics happening at the center of countless stars—and, hopefully, devise a way to use that physics to one day power our world.