Fusion reactors--the near-mythic energy sources that have been on the horizon for half a century--may be coming one step closer. The U.S. Department of Energy's Princeton Plasma Physics Laboratory has begun building a machine called a compact stellarator to perfect the magnetic fields needed to control the thermonuclear activity involved. Inside are 18 of the most complex electromagnets ever designed. Engineers are creating 6000-pound coils in three shapes. When linked, the coils form a precisely shaped magnetic field that can manipulate superhot ionized gas, called plasma. No matter what is learned, fusion power plants remain decades, and billions of dollars, away from reality.
>> 100 million degrees Celsius: To get like-charged nuclei to bond, the plasma must be hotter than the sun's core.
>> $74 million: Federal outlay, to date, to build the stellarator project.
>> 1000 Megawatts: The power a future fusion reactor could generate.
>> Late 2011: Year in which the National Compact Stellarator Experiment is due to start operations.