Hot plasma in a tokamak is like a temperamental beast: you need to hold it in, but not let it overheat. In the ASDEX Upgrade reactor, researchers found a regime where plasma eddies solve this problem on their own. Stochastic modeling showed that oscillations at the plasma edge fling out blobs, like bubbles from a boiling pot. These blobs carry away excess heat, while the main plasma stays stable.
The secret lies in the teamwork of two types of waves: some rock the plasma from within, others tear at its very edge. Together, they create rhythmic ejections that keep the reactor walls from overheating. Previously, turbulence was thought to only hinder confinement, but here it turns out to be beneficial.
Now engineers can more accurately design future reactors. Instead of fighting the eddies, they can harness them, like a sail uses the wind.
The plasma temperature in a tokamak reaches 150 million degrees — ten times hotter than the Sun's core.
In Liu Cixin's novel "The Three-Body Problem," fusion is the key to saving civilization, but controlling plasma remains a stumbling block.