For decades, fusion energy has promised humanity a revolutionary power source that is clean, safe,...
For decades, fusion energy has promised humanity a revolutionary power source that is clean, safe, and virtually limitless.
Unlike fossil fuels or even traditional nuclear power, fusion mimics the energy production of the sun, fusing atoms together to release massive amounts of energy without greenhouse gas emissions or long-lived radioactive waste.
However, one stubborn problem has kept this dream out of reach: the inability to reliably contain high-energy particles inside fusion reactors.
These particles — essential to keeping the plasma hot enough for sustained fusion — tend to escape through holes in the reactor’s magnetic field, draining energy and halting the reaction.
Now, a team of researchers from The University of Texas at Austin, Los Alamos National Laboratory, and Type One Energy Group has discovered a faster, more accurate way to fix those magnetic flaws.
This could accelerate the development of stellarators, one of the most promising fusion reactor designs, by a factor of ten.
Why particles keep leaking
Fusion reactors depend on superheated plasma confined within strong magnetic fields.
A major issue has been the escape of high-energy alpha particles, which are supposed to help maintain the plasma’s heat and pressure. When these particles leak, they weaken the reaction, preventing the conditions necessary for sustained fusion.
Stellarators particularly rely on intricate magnetic coils to create a “magnetic bottle” that traps these particles.
However, these magnetic fields often contain invisible “holes” through which alpha particles escape. Pinpointing and correcting these flaws using traditional methods based on Newton’s laws is computationally intensive and slow.
The design process becomes cumbersome as engineers need to simulate and test hundreds of coil variations.
New approach cuts design time by 90%
To make the process manageable, scientists have long used a faster but far less accurate technique called perturbation theory, which often leads to serious errors.
The new method, developed by the research team and detailed in their recent paper, uses symmetry theory to accurately locate and eliminate magnetic holes while requiring just a tenth of the computational power.
“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 first author of the paper. “It’s a paradigm shift in how we design these reactors.”
Impact beyond stellarators: Tokamak safety gains
Although the method was designed for stellarators, its applications extend to tokamaks — the more widely studied cousin of stellarators.
In tokamaks, the danger lies in runaway electrons, which can puncture the reactor walls if not properly contained. The new technique can help map the weak spots in magnetic fields, potentially improving reactor safety and durability.
“There is currently no practical way to find a theoretical answer to the alpha-particle confinement question without our results,” Burby said.
“Direct application of Newton’s laws is too expensive. Perturbation methods commit gross errors. Ours is the first theory that circumvents these pitfalls.”
Toward commercial fusion energy
This breakthrough not only addresses a specific technical bottleneck but also provides a concrete tool for companies racing to commercialize fusion power.
Type One Energy Group, which contributed to the research, is actively working to build next-generation stellarators for energy production.
The full study is published in Physical Review Letters.