There are many stumbling blocks on the racetrack to nuclear fusion, the reaction at the core of the sun that combines atoms to make energy: Generating more energy than it takes to power the reactors, developing reactor-proof building materials, keeping the reactor free from impurities, and restraining that fuel within it, to name a few. 

Now, researchers from Princeton University and its Princeton Plasma Physics Laboratory have developed an AI model that could solve that last problem. This model predicts, and then figures out how to avoid, plasma becoming unstable and escaping the strong magnetic fields that hold it inside certain donut-shaped reactors. They published their findings Wednesday in the journal Nature.

Donut-shaped tokamak reactors rely on magnets to squeeze plasma particles close together and keep them constantly spinning around a ring, creating a lasting fusion reaction. They're one of the front-runners in designs for a practical fusion reactor. But if there's one little disruption to the magnetic field lines running through the plasma, the delicate balance keeping it all contained gets out of whack: The plasma escapes the magnets' clutches and the reaction ends. 

Chijin Xiao, a plasma physicist at the University of Saskatchewan who wasn't involved in the study, explained that these instabilities can lead to catastrophic consequences. "When the plasma stops operating, there are several risks: one is that all the energy stored in the plasma is going to be released as thermal energy and may damage the wall of the reactor," she said. "More importantly, a sudden change in the [magnetic] current can introduce a great deal of force on the reactor that can really destroy the device."