Scientists have achieved a breakthrough in magnetic confinement that could potentially quicken the advancement for fusion energy by enabling faster and more accurate ways to trap high-energy particles within fusion reactors.
At the heart of the new design is a theoretical approach that offers a promising solution to one of fusion energy’s most demanding problems: how to prevent energy-draining particles from escaping reactor chambers.
The discovery, funded by the U.S. Department of Energy, was made by scientists from The University of Texas at Austin, Los Alamos National Laboratory, and Type One Energy Group, who report that their new method provides a more efficient means of designing leak-proof magnetic fields for fusion reactors, particularly stellarators, at a pace ten times faster than those of traditional techniques relied on by physicists.
Most promising of all, the new method can achieve this while still preserving the accuracy required for operating these high-energy reactors, a factor that has long hindered progress in magnetic confinement approaches in the past.
Magnetic Containment in Fusion Reactors
Fusion energy research has long been hampered by the challenge of how to keep high-energy alpha particles contained within magnetic fields in fusion reactors. Under the extreme conditions that occur within reactors, these particles can sometimes leak out, which cools plasmas within the reactor and degrades the fusion process.
Since these particles are such a critical component for maintaining extreme heat and density required for sustained fusion reactions, engineers have relied on complex systems in the past that employ magnetic confinement to trap these particles. However, identifying and sealing gaps in the magnetic fields requires a significant amount of computational power, as well as time.
“What’s most exciting is that we’re solving something that’s been an open problem for almost 70 years,” said Josh Burby, assistant professor of physics at UT and the first author of a new study detailing the team’s work.
Burby called the new work “a paradigm shift in how we design these reactors.”
Stellarators in Focus
A key focus for the team’s research involves stellarators, which are fusion reactors that feature a toroidal (donut-shaped) design that rely on elaborate external windings that control the magnetic fields produced within. The coils of these devices, which were first designed in the 1950s, generate what is known as a “magnetic bottle” to confine plasma and high-energy particles.
In the past, engineers have relied on Newton’s laws of motion to map particle trajectories and locate leaks, which involves highly precise, but computationally intensive work. When it comes to designing a stellarator, the simulation of hundred or even thousands of variations may be required in order to ensure the elimination of leaks, a task that can very quickly become impractical.
Moving toward streamlining the process, scientists often employ a less precise method known as perturbation theory, which allows them to determine the approximate locations where leaks are likely to form. This shortcut helps save time and work, but often sacrifices accuracy, which can impede progress in stellarator development.
The new method developed by Burby and his collaborators, leveraging symmetry theory instead, offers both speed and the kind of precision required for optimal fusion reactions.
“There is currently no practical way to find a theoretical answer to the alpha-particle confinement question without our results,” Burby recently said of the team’s work. “Direct application of Newton’s laws is too expensive.”
“Perturbation methods commit gross errors,” Burby said. “Ours is the first theory that circumvents these pitfalls.”
The new process could have applications beyond just stellarators, since the team believes there may be applications regarding tokamak reactors, another of the leading magnetic fusion devices currently in use. In tokamaks, runaway electrons can often damage the walls of reactors if they manage to escape.
With the team’s new method, researchers may be able to more accurately map out potential leakage points for these electrons, which may offer a valuable tool for improving reactor safety and efficiency.
The new findings were detailed in a paper, “Nonperturbative Guiding Center Model for Magnetized Plasmas,” in Physical Review Letters.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. He can be reached by email at micah@thedebrief.org. Follow his work at micahhanks.com and on X: @MicahHanks.