Poloidal magnetic flux function
= Poloidal magnetic flux function
{title2=$\psi$}
= Axisymmetric magnetic flux function
{synonym}
For $\mathbf B_p=\nabla\psi\times\nabla\phi$, surfaces $\psi=\text{constant}$ are poloidal magnetic surfaces and $2\pi\psi$ is magnetic flux up to the choice of axial reference value.