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The interior of the Massachusetts Institute of Technology’s (MIT’s) Alcator C-Mod tokamak. A team led by Princeton Plasma Physics Laboratory’s C.S. Chang recently used the Titan supercomputer

The same fusion reactions that power the sun also occur inside a tokamak, a device that uses magnetic fields to confine and control plasmas of 100-plus million degrees. Under extreme temperatures and pressure, hydrogen atoms can fuse together, creating new helium atoms and simulta...

Pellet selector

When it’s up and running, the ITER fusion reactor will be very big and very hot, with more than 800 cubic meters of hydrogen plasma reaching 170 million degrees centigrade. The systems that fuel and control it, on the other hand, will be small and very cold. Pellets of frozen gas will be shot int...