Monte Carlo simulation of edge ion dynamics in the presence of collisions and a radial electric field

The dynamics of ions in the vicinity of the last closed flux surface in tokamaks is a topic of current interest because of its significance to the first wall and divertor surfaces as well as to the LH-transition. In the presence of a radial electric field, the ion trajectories and the structure of the ion phase space are altered. The fields can have secondary effects e.g. through the radial current resulting from the direct ion orbit loss. A Monte Carlo method for studying the edge ion behaviour is presented here. The direct ion orbit loss of the main plasma ions is analyzed under various plasma conditions, and the effect of boundary conditions on direct ion orbit loss is studied. (orig.)