An experimental fusion reactor built by the Chinese Academy of Science has hit a major milestone. The Experimental Advanced Superconducting Tokamak (EAST) has maintained a plasma pulse for a record 102 seconds at a temperature of 50 million degrees – three times hotter than the core of the sun.

The EAST is a tokamak, or a torus that uses superconducting magnets to compress plasma into a thin ribbon where atoms will fuse and energy will be created. For the last fifty years, most research has been dedicated to the study of tokamaks in producing fusion power, but recently several projects have challenged this idea. The Wendelstein 7-X  stellarator at the Max Planck Institute for Plasma Physics recently saw first plasma and if results go as expected, the stellarator will be the design used in fusion power plants. Tokamaks have shortcomings; they can only be ‘pulsed’, not used continuously, and we haven’t been building tokamaks large enough to produce a net gain in power, anyway.

Other tokamaks currently in development include ITER in France. Theoretically, ITER is large enough to attain a net gain in power at 12.4 meters in diameter. EAST is much smaller, with a diameter of just 3.7 meters. It is impossible for EAST to ever produce a net gain in power, but innovations in the design that include superconducting toroidal and poloidal magnets will surely provide insight into unsolved questions in fusion reactor design.