What is a Tokamak?

The most successful and promising fusion confinement device is known as a tokamak. The word tokamak is actually an acronym derived from the Russian words toroid-kamera-magnit-katushka, meaning "the toroidal chamber and magnetic coil." This donut-shaped configuration is principally characterized by a large current, up to several million amperes, which flows through the plasma. The plasma is heated to temperatures more than a hundred million degrees centigrade (much hotter than the core of the sun) by high-energy particle beams or radio-frequency waves.

>> Inside of the Princeton Plasma Physics Laboratory Tokamak TFTR.