Flux coordinate system

In the above, we do not specify which coordinate system to use. In this article, we will use the straight-line magnetic surface coordinate system (i.e. flux coordinate system) $(\psi, \theta, \zeta)$. The details of this coordinate system are given in my notes on tokamak equilibrium (/home/yj/theory/tokamak_equilibrium/tokamak_equilibrium.tm).