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 results also give researchers a clearer picture of the contrast between the two tokamak designs.

From Science Daily • May 28, 2024

"There is certainly a big difference between the stability boundary for the apple shape and the standard-shaped tokamak, and our model can now somewhat explain why that difference exists," he said.

From Science Daily • May 28, 2024

A tokamak is a donut-shaped device that uses magnetic fields to hold a plasma.

From Science Daily • May 14, 2024