For decades scientists have sought to generate clean energy by instigating the kind of sustained nuclear fusion reactions that power the sun. On Earth this feat requires taming plasma (electrically charged gas) at temperatures around 150 million degrees Celsius, 10 times as hot as the inferno at the sun's core. The most ambitious attempt: the 10 billion euro International Thermonuclear Experimental Reactor (ITER), being built in France.

Recent computer simulations incorporating the geometry of ITER's doughnut-shaped reaction chamber and its powerful, plasma-confining magnetic fields have helped researchers predict the behavior of turbulent plasma inside the machine. The long fibers seen here represent the concentration of electrons in the plasma flowing through the chamber, with red and orange showing higher-density regions. Because plasma makes up more than 99 percent of the visible universe, such simulations also offer insight into a wide range of astrophysical phenomena, including stellar formation and the energetic events that create cosmic rays.