Fusion
Tokamak
A toroidal magnetic-confinement device that uses plasma current as part of the confining field.
Labelled system
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Original ENERGY ATLAS schematic. Interactive 3D is opt-in on this page.
Create the main toroidal magnetic field around the plasma.
Overview
The tokamak is the most developed magnetic-fusion configuration. Toroidal field coils create a donut-shaped magnetic field. A central solenoid drives current in the plasma, adding a poloidal field so field lines twist helically. That twist is essential: a purely toroidal field lets particles drift out of the plasma.
How it works
Fuel is ionized into plasma inside a vacuum vessel. Magnetic fields keep the hot plasma away from the walls. Additional heating — neutral beams and radio-frequency waves — raises temperature. A divertor guides particles and heat to target surfaces. Because the plasma current is typically transformer-driven, many tokamaks are pulsed, though current-drive research aims at longer pulses.
Components
Toroidal field coils
Create the main toroidal magnetic field around the plasma.
Central solenoid
Acts as the primary of a transformer that drives plasma current.
Poloidal field coils
Shape and position the plasma.
Vacuum vessel
High-vacuum chamber that contains the plasma.
Divertor
Exhausts heat and particles from the plasma edge.
Keep exploring
Articles
Tokamaks
The word "tokamak" is of Russian origin and means "toroidal chamber and magnetic coils." This magnetic confinement system holds plasma in magnetic fields of toroidal shape. The first tokamak, the T-1, started operation in 1958 in Russia, and since then the greatest advances in th
16 min read
Material for Magnetic Coils
The word "tokamak" is of Russian origin and means "toroidal chamber and magnetic coils." This magnetic confinement system holds plasma in magnetic fields of toroidal shape. The first tokamak, the T-1, started operation in 1958 in Russia, and since then the greatest advances in th
5 min read
Magnetic Confinement
Charged particles follow magnetic field lines. Tokamaks and stellarators twist those lines into a torus so plasma cannot leak out too quickly.
8 min read