Future Tech: Fusion

For a moment, a miniature sun lights up inside the Princeton Plasma Physics Laboratory, a small campus of anonymous white buildings three miles northeast of Princeton University in New Jersey. Within a tangled merry-go-round of wires and red copper coils, a ball of plasma—a charged gas of hydrogen nuclei and electrons—heats up to 70 million degrees Fahrenheit. The plasma blazes supernova bright, then instantly goes black. Although the whole episode lasts less than 500 milliseconds, physicist Masayuki Ono seems pleased. "For plasma that's a long time; the particles do a lot in a hundred milliseconds," he says.