Poloidal magnetic field (${\mathbf{B}}_p=B_R{\mathbf{e}}_R+B_z{\mathbf{e}}_z$)

A poloidal magnetic field lies in meridional planes through the symmetry axis, in contrast to a toroidal magnetic field. For an axisymmetric vector field, it is represented by a poloidal magnetic flux function as ${\mathbf{B}}_p=R^{-1}\nabla \Psi \times {\mathbf{e}}_{\varphi }$.