Calculation of Hamada coordinates for a large-aspect-ratio tokamak

The application of the well-known moment equation approach to neoclassical transport requires the use of Hamada coordinates in three-dimensional toroidal plasmas. The lack of analytical expressions and the difficulty associated with the numerical calculation of these coordinates has strongly limited the use of this approach. In this paper analytical calculations of Hamada coordinates for a large-aspect-ratio tokamak are presented. Knowledge of these coordinates for this relatively simple two-dimensional case will allow, for the first time, a general analytical application of the moment equation approach, and also a check of this approach against well-known results. In particular, it is shown here that the approach correctly reproduces the Pfirsch–Schlüter diffusion rate.