Stellarator
A magnetic confinement fusion device that produces a helical magnetic field using complex, 3D non-planar external electromagnetic coils without requiring net plasma current.
Governing formula
Rotational Transform ι = 1 / q (Generated entirely by 3D external coils)
SI unit
Dimensionless Magnetic Transform
In depth
Invented by Lyman Spitzer in 1951. Unlike tokamaks, stellarators do not require driven internal plasma currents, inherently eliminating current-driven plasma disruptions and enabling steady-state continuous fusion operation.
Examples in the real world
The Wendelstein 7-X (W7-X) advanced modular stellarator operating in Greifswald, Germany.