Tokamak
A tokamak is a toroidal, (doughnut shaped) magnetic plasma confinement device, the leading candidate for magnetic fusion energy. The term tokamak comes from the Russian words: "toroidalnaya", "kamera", and "magnitnaya", which mean "toroidal, chamber, magnetic". The last letter g was replaced by k to avoid analogy with the word magic. It was invented in the 1950s by Igor Yevgenyevich Tamm and Andrei Sakharov.The tokamak is characterized by the use of the plasma current to generate the helical component of the magnetic field necessary for stable equilibria. This can be compared to another toroidal magnetic confinement device, the stellarator, in which all of the confining magnetic fields are produced by external coils and there is a negligible current flowing in the plasma.
The "Novillo" tokamak, the smallest in the world
See also: plasma physics, nuclear fusion, stellarator, Reversed field pinch, magnetic mirror, magnetohydrodynamics, Farnsworth-Hirsch Fusor, JET, ITER