For the last six decades, LLNL researchers and their colleagues have been striving to achieve one of the most challenging goals in all of science and a primary objective of NIF: fusion ignition. This effort drives excellence in every aspect of NIF operations—the laser, targets, optics, diagnostics, and, of course, the people who make it all possible.
In an inertial confinement fusion (ICF) experiment, the energy of NIF’s 192 lasers are concentrated into a tiny hollow cylinder called a hohlraum, generating x rays that drive the implosion of a capsule filled with hydrogen fuel. When the implosion reaches its peak, the deuterium and tritium atoms fuse and release a tremendous amount of energy. Ignition will be achieved when a self-sustaining thermonuclear reaction releases more energy than the amount of energy absorbed by the target.
“Nature does not give up her secrets easily.”
—NIF Senior Scientist John Lindl
While achieving ignition on NIF has proven more challenging than first expected, we gain new understanding of the process with every experiment. We have learned important lessons about the limitations of our simulations and have used that knowledge to address issues and continually improve implosion performance.
At the same time, each ignition experiment advances the science of ensuring the reliability of the nation’s nuclear stockpile as well as the eventual use of fusion as a safe, clean, and virtually unlimited energy source.
“Every time we make progress, we can better understand what challenges lie ahead. We understand our system a lot better than before, and we’ve been able to take that understanding and translate it into increased performance. I’m very excited about the progress we’ve been able to make, and where we can go next.”
—Laura Berzak Hopkins, lead designer for the high-yield experiments.
Since the first NIF laser shots, scientists have set records for neutron yield and the amount of energy generated. For the first time ever in a laboratory setting, we have seen the initial signs of “alpha heating”—when the alpha particles generated by fusion reactions in the target’s central hot spot deposit their energy in the surrounding cold fuel, stimulating additional fusion reactions. This process, if better contained, would lead to a self-sustaining “burning plasma” and eventually, as other issues are resolved, to fusion ignition.
We are now poised to further improve NIF’s performance by coupling more laser energy to the capsule while maintaining symmetry control. We also are pursuing strategies like novel hohlraum designs; larger capsules; magnetized targets; new methods for finishing, mounting, and filling capsules; and increased laser energy.
We owe our progress to the decades of remarkable work by previous generations of LLNL scientists and engineers who advanced the field of high energy density and ICF science to where it is today. A new generation of LLNL researchers, some of whom are pictured below, are carrying on this tradition of excellence.
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