Spherical tokamak - Wikipedia

A spherical tokamak is a type of fusion power device based on the tokamak principle. It is notable for its very narrow profile, or aspect ratio . A traditional tokamak has a toroidal confinement area that gives it an overall shape similar to a donut, complete with a large hole in the middle.

Mark Anthony Hernandez Motaghy

Source: Spherical tokamak - Wikipedia