tokamak

American  

[toh-kuh-mak, tok-uh-] / ˈtoʊ kəˌmæk, ˈtɒk ə- /

noun

Physics.

1. a type of experimental nuclear fusion reactor in which a plasma of atoms circulates in a toroidal tube and is confined to a narrow beam by an electromagnetic field.

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tokamak British  

/ ˈtɒkəˌmæk /

noun

1. physics a toroidal reactor used in thermonuclear experiments, in which a strong helical magnetic field keeps the plasma from contacting the external walls. The magnetic field is produced partly by current-carrying coils and partly by a large inductively driven current through the plasma

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Etymology

Origin of tokamak

1960–65; < Russian tokamák, acronym from toroidálʾnaya kámera s aksiálʾnym magnítnym pólem toroidal chamber with an axial magnetic field

Example Sentences

China has invested heavily in its own tokamak program, achieving record plasma temperatures and confinement times.

From The Wall Street Journal • Dec. 28, 2025

Previously, researchers led by Kolemen successfully deployed a separate AI controller to predict and avoid another type of plasma instability in real time at the DIII-D tokamak.

From Science Daily • Jun. 5, 2024

"The model refines the thinking on stabilizing the edge of the plasma for different tokamak shapes," said Jason Parisi, a staff research physicist at PPPL.

From Science Daily • May 28, 2024

"If you could have a plasma in a tokamak that was all pedestal, and if the gradients were really steep, you would get a really high core pressure and a really high fusion power."

From Science Daily • May 28, 2024

Such momentary, explosive ELMs need to be avoided because they can damage the inner components of a tokamak, draw impurities from the tokamak walls into the plasma and make the fusion reaction less efficient.

From Science Daily • May 14, 2024