Twisty device explores alternative path to fusion

Is the search for fusion energy, long dominated by doughnut-shaped devices called tokamaks, about to undergo a shape shift? Just as ITER, the world’s largest tokamak—and at tens of billions of dollars the most expensive—nears completion in the hills of southern France, a much smaller testbed with a twistier geometry will start throttling up to full power in Germany. If the 16-meter-wide device, called a stellarator, can match or outperform similar-size tokamaks, it could cause fusion scientists to rethink the future of their field. Stellarators have several key advantages, including a natural ability to keep the roiling superhot gases they contain stable enough to fuse nuclei and release energy. Even more crucial for a future fusion power plant, they can theoretically just run and run, whereas tokamaks must stop periodically to reset their magnet coils. In runs of a few seconds, the €1 billion German machine, dubbed Wendelstein 7-X (W7-X), is already getting “tokamak-like performance,” says plasma physicist David Gates, proving adept at preventing particles and heat from escaping the superhot gas. If W7-X can achieve long runs, “it will be clearly in the lead,” he says. “That’s where stellarators shine.” Theorist Josefine Proll of the Eindhoven University of Technology is equally enthusiastic: “All of a sudden, stellarators are back in the game.” The encouraging prospects are inspiring a clutch of startup companies, including one for whic...
Source: ScienceNOW - Category: Science Source Type: news