Nuclear Fusion researchers at the Lawrence Livermore National Laboratory working in the National Ignition Facility have recorded the highest ever energy output from an experiment to date. Totaling 1.3 megajoules, the record achievement moves fusion researchers incredibly close to the ultimate goal of “greater gain than unity,” the definition adopted by the National Academy of Sciences back in 1997 for a fusion reactor that puts out more energy than it takes in.
BACKGROUND: HISTORIC NUCLEAR FUSION ENERGY PROGRESS
Fusion energy pioneers have spent decades working on inertial confinement fusion research, resulting in a range of improvements. These include new diagnostic tools, improvements in the fabrication of the capsule shell, improved fill tube and hohlraum, (a gold cylinder that holds the target capsule) more refined laser precision, and additional overall design changes to increase the energy coupled to the implosion and to the compression of that implosion.
These efforts led to a record output in 2018, a figure that was dwarfed by the latest test results.
ANALYSIS: A NEW WORLD RECORD FOR FUSION ENERGY OUTPUT
According to the release from LLNL, “the experiment was enabled by focusing laser light from NIF — the size of three football fields — onto a target the size of a BB that produces a hot-spot the diameter of a human hair, generating more than 10 quadrillion watts of fusion power for 100 trillionths of a second.”
All in all, 192 laser beams are used in the ignition experiments, with their total output lasting only a few billionths of a second. In that time, the NIH heats the target sample up to more than 180 million degrees F, and under pressures more than a billion Earth atmospheres.
Although more analysis of the data is required to pinpoint the actual output of the reaction, estimates show an 8x improvement over similar experiments in the spring of 2021, and a 25x improvement over the 2018 record. By achieving a roughly two thirds output to input ratio, meaning the system put out about 2/3 the input energy from the laser array, this is the closest researchers have come to greater than unity output.
“This result is a historic step forward for inertial confinement fusion research, opening a fundamentally new regime for exploration and the advancement of our critical national security missions. It is also a testament to the innovation, ingenuity, commitment and grit of this team and the many researchers in this field over the decades who have steadfastly pursued this goal,” said Kim Budil, Director of LLNL. “For me it demonstrates one of the most important roles of the national labs – our relentless commitment to tackling the biggest and most important scientific grand challenges and finding solutions where others might be dissuaded by the obstacles.”
OUTLOOK: FUTURE OF NUCLEAR FUSION EXPERIMENTS
More tests are planned by the NIF team, but those are expected to take several months to prepare and execute.
“Gaining experimental access to thermonuclear burn in the laboratory is the culmination of decades of scientific and technological work stretching across nearly 50 years,” said Los Alamos National Laboratory Director Thomas Mason. “This [result] enables experiments that will check theory and simulation in the high energy density regime more rigorously than ever possible before and will enable fundamental achievements in applied science and engineering.”
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