Furthering Fusion

Generating abundant, low-cost, clean energy took one step closer to reality, as a team of researchers, including UT Austin assistant professor of physics Josh Burby, solved a longstanding problem in fusion energy.

Leakage of high-energy alpha particles from reactors is common, but such leakage prevents plasma from getting hot and dense enough to sustain a fusion reaction. To prevent leakage, engineers design elaborate magnetic confinement systems, but a tremendous amount of computational time is required to predict the locations of holes in the magnetic field and eliminate them.

Burby and his team discovered a computational shortcut that can help engineers design leak-proof magnetic confinement systems 10 times as fast as the gold standard method, without sacrificing accuracy. This advance addresses the biggest challenge that’s specific to the stellarator, a type of fusion reactor proposed in the 1950s.

A stellarator uses external coils carrying electric currents that generate magnetic fields to confine plasma and high-energy particles, called a “magnetic bottle.”

Currently, scientists can identify where the holes are in the magnetic bottle using Newton’s laws of motion. The method is precise but takes an enormous amount of computational time. To save time and money, scientists and engineers routinely use perturbation theory, a simpler but less accurate approach for approximating where the holes are. The new method relies on symmetry theory, a different way of understanding the system.

“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.”

A computational shortcut can help lower the time and cost of designing fusion reactors.