World's largest laser used to initiate groundbreaking fusion reaction

This is a historic milestone in the quest for a clean nuclear energy source.
Thomas Velasquez
Nature Laser
Nature Laser

llnl.gov  

Scientists at Lawrence Livermore National Laboratory in California have made a major breakthrough in the field of nuclear fusion, sparking hope for a new carbon-free power source.

The team used the world's largest laser to initiate a fusion reaction that produced more energy than it took to create, marking a historic milestone in the quest for a clean nuclear energy source. Nuclear fusion has long been seen as a potential solution to the world's energy needs, as it could provide abundant electricity without emitting greenhouse gasses or producing long-lasting nuclear waste.

How did they do it?

The team at Lawrence Livermore Lab used a method called inertial confinement at the National Ignition Facility (NIF) to target a tiny sphere of deuterium-tritium fuel with 192 lasers, generating X-rays inside a gold can and imploding the sphere of fuel. The lasers delivered 2.1 megajoules of energy and yielded 3.15 megajoules in return, achieving a fusion energy gain above 1. This result was verified by diagnostic tools developed by the MIT Plasma Science and Fusion Center  (PSFC). The PSFC's magnetic recoil neutron spectrometer (MRS) was one of the key systems used to measure the absolute neutron yield from the experiment, as it can accurately interpret the neutron signals from an implosion.

Researchers worldwide have been working towards achieving fusion ignition and energy gain in a laboratory setting since the late 1950s, recognizing it as a major challenge for the 21st century. To achieve ignition, the internal fusion heating power must be strong enough to overcome the processes that cool the fusion plasma, creating a positive feedback loop that quickly increases the plasma temperature. The inertial confinement method the NIF (National Ignition Facility) researchers use can initiate a "fuel burn propagation" into the surrounding dense and cold fuel that leads to energy gain from fusion.

What does this mean for the future?

The achievement at Lawrence Livermore Lab brings the dream of nuclear fusion as a viable energy source closer to reality, but it is important to note that the technology is still some 20-30 years away from being viable on a commercial scale. That timeline puts fusion beyond the scope of significantly being used to reach the world's net-zero emissions goals by 2050, which means that fusion could be the carbon-free energy source of the future but not of the current global energy transition.

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Still, the team at Lawrence Livermore Lab is determined to keep pushing the boundaries of what is possible with nuclear fusion. In order to do this, they will need to perfect the use of the laser and keep increasing the amount of energy produced in the reaction. This will require a lot of precision calibration, as well as possibly upgrading the facility itself, which would require funding and approval from the Department of Energy.

Arthur Pak, leader for diagnostics on the experiment, spoke about the significance of the team's achievement in an interview with Bloomberg News: "You can work your whole career and never see this moment. You're doing it because you believe in the destination, and you like the challenge. When humans come together and work collectively, we can do amazing things."

The ultimate goal is to make the process of nuclear fusion simpler, easier, and more repeatable

The next fusion test for the team at Lawrence Livermore Lab is scheduled for February, with several more experiments planned in the months following. Pak and his fellow researchers are now faced with the daunting task of reliably repeating this process with increasingly higher energy yield. The ultimate goal is to make the process of nuclear fusion simpler, easier, and more repeatable so that it can be done more than once a day. This is an incredible scientific and engineering challenge, but one that the team is more than ready to take on.

The potential of nuclear fusion as an energy source has captured the scientific imagination for decades. It is already used to give modern nuclear weapons their devastating power, but the dream is to tame it for civilian energy demand. This latest breakthrough brings us one step closer to harnessing the power of nuclear fusion as a practical and reliable source of energy for homes, businesses, and entire communities. The potential for this discovery to revolutionize the way we generate and use energy is truly exciting and holds great promise for a cleaner, more sustainable future.