Tokamak JET. (Source: Wikipedia.org)

A device for magnetic confinement of plasma by a combination of a toroidal magnetic field and a current flowing through the plasma in which conditions for thermonuclear fusion ignition can be achieved. The word “tokamak” is of Russian origin and is an acronym for “TOroidalnaya KAmera i MAgnitnye Katushki” — toroidal chamber and magnetic coils. The magnetic field necessary to keep the hot plasma inside the toroidal chamber is generated as a combination of the field of the toroidal coils and the magnetic field generated by the current flowing through the plasma. Since the current in the plasma is induced on the transformer principle, the tokamak is a pulse device. The first tokamak was commissioned in the 1950s. The world’s largest tokamak, ITER, is currently under construction, and its chamber will contain 840 m³ of plasma.