Tokamak reactor

The structure that will house one of the largest and most ambitious energy experiments in history is now complete, with engineers working on the ITER Tokamak Building swinging their last pylon into place in readiness for the reactor's assembly stage.

Nuclear fusion could be an essentially unlimited energy source, but large eruptions in the plasma can damage reactors. But now physicists have found a way to prevent those large eruptions, by triggering lots of small ones through the injection of tiny pellets of beryllium.

A relatively new player on the nuclear fusion scene, a UK company called Tokamak Energy, is claiming a new milestone in the area after heating its ST40 device to 15 million degrees Celsius, similar to temperatures found at the center of the Sun.