An Etymological Dictionary of Astronomy and Astrophysics

A machine producing a → toroidal magnetic field for confining a → plasma in
→ nuclear fusion research.

See also: From Rus. Tokamak, acronym from toroidal’naya kamera s magnitnymi katushkami “toroidal chamber with magnetic coils.”
It was invented in the 1950s by Soviet physicists Igor Yevgenyevich Tamm and Andrei Sakharov (who had been inspired by an original idea of Oleg Lavrentyev).