Poloidal field and Poloidal field coils

The poloidal field is one component of the magnetic field and essential for plasma confinement in a tokamak. It is generated by the plasma current; this is in contrast to the larger toroidal field, which is generated externally. In a tokamak, the poloidal field is induced both internally, by the current driven in the plasma (one of the plasma heating mechanisms), and externally, by poloidal field coils that are positioned around the perimeter of the vessel.