In the earliest days of the Cold War, physicists on both sides of the Iron Curtain raced to harness energy from nuclear fusion, which could, in principle, provide nearly limitless electricity. Innovative devices with names like pinch machines, levitrons, and superstators flourished, and for most of the 1950s it was unclear which would eventually prove most promising. But in 1968, at the Third International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Soviet scientists announced that their tokamak—which confined a thermonuclear plasma within a donut-shaped magnetic field—had achieved temperatures 10 times higher than any other experiment (1). The interior of the Wendelstein 7-X stellarator. Visible are the plasma vessel, one of the stellarator coils, a planar coil, part of the support structure, and the cryostat together with a lot of cooling pipes and power supply lines. Photo by Wolfgang Filser and image courtesy of Max Planck Institute for Plasma Physics. Although the figure was initially met with shock and skepticism, it was quickly confirmed by British physicists (2). The tokamak has remained the dominant research avenue for pursuing fusion until today, with machines like the multibillion-euro International Thermonuclear Experimental Reactor (ITER), the world’s largest confined plasma physics experiment, currently under construction in France. But another invention, a close cousin of the tokamak called a stellarator, has lately begun to receive renewed attention. Despite their complexity, stellarators offer ways around many of the instabilities that plague tokamaks. “In simple words, the stellarator is just tamer,” says plasma physicist Thomas Klinger, codirector of the Wendelstein 7-X (W7-X) stellarator experiment in Greifswald, Germany. “It’s difficult to build, but easier to run.” Researchers now think the advantages of stellarators might extend to one more area that’s crucial to any real-world fusion reactor: the management of turbulence. Scientists have put enormous effort into …