The word tokamak is a Russian acronym for “тороидальная камера с магнитными катушками”, which means “toroidal chamber with magnetic coils”. They are donut-shaped machines that use magnets to confine very hot plasmas (gas heated at several million degrees).


Tokamaks are the most successful fusion device and some have produced megawatts of fusion power. More than 180 tokamaks have been built around the world. Today, there are three large tokamaks currently operating in Europe: TCV in Switzerland, WEST in France, and ASDEX-U in Germany. A fourth, JET, was just shut down in the UK after 40 years of record-breaking performance.