Impure tokamak pedestals with strong radial electric field

A high confinement mode pedestal has density and potential variation on the poloidal ion gyroradius scale. As a result, the ExB-drift associated with radial electric field can compete with the poloidal projection of parallel ion streaming, making alternate neoclassical descriptions necessary. In addition, Alcator C-Mod experiments\footnote{C. Theiler et al., \textbf{Nucl. Fusion} 54,083017} make it clear that the impurity diamagnetic drift contribution must be allowed to be comparable to the impurity poloidal and toroidal flows to measure the radial electric field. Furthermore, Churchill et al.\footnote{R.M. Churchill et al., \textbf{Nucl. Fusion} 53,122002} experimentally observe stronger poloidal variation of the impurity density than predicted by the most comprehensive theoretical models developed to date. A neoclassical ordering valid for slowly varying background ion temperature profiles in subsonic pedestals has been formulated that allows impurity diamagnetic flow effects to enter to lowest order. It results in strong poloidal impurity variation and possibly provides a more realistic model for pedestal observations, by extending the seminal work of Helander.\footnote{P. Helander, \textbf{Phys. Plasmas} 5,3999}