Physicists Crack Fusion Mystery

 One reason it's taking decades to develop fusion reactors that can generate electricity is that physicists don't completely understand what's going on in the high-temperature plasma inside a reactor. Under certain conditions, the plasma—which is where fusion reactions take place—disappears in under a millisecond.

A new theory developed by researchers at the U.S. Department of Energy's Princeton Plasma Physics Laboratory (PPPL) explains what happens just before the plasma disappears. The explanation could help engineers design better reactors. And that might help them increase the power output of a reactor, perhaps doubling the electricity they could produce, and making fusion reactors more economical.

Researchers have made a lot of progress on fusion technology—since 1970, the energy produced in experimental fusion reactors has increased by about 12 orders of magnitude, greater than the improvement in processing power in microchips over the same period, says Martin Greenwald, a fusion researcher at MIT. But for all the improvements in fusion research reactors, they still aren't useful—they don't produce more energy than they consume, and they can't be run continuously, both of which would be necessary for a power plant.