The ratio between the major radius and the minor radius of a tokamak. Aspect ratio describes what the toroidal chamber in which the plasma is created exactly looks like. The major radius is the distance from the centre of the tokamak to the centre of the plasma, while the minor radius is the distance from the centre of the plasma to the edge of the chamber. High aspect ratio tokamaks are shaped like a tyre with a large central hole, while low aspect ratio tokamaks are called spherical tokamaks and more resemble a cored apple.