A tokamak parameter that indicates the distance from the centre of the plasma to the edge of the chamber. If we imagine the tokamak chamber as a jam-filled donut, then the minor radius is the distance from the centre of the jam to the nearest edge of the donut. In the case of a tokamak chamber, which is D-shaped in cross-section and therefore not exactly circular, the parameter elongation is also given, indicating how much the chamber is elongated in the vertical direction.