Global modelling of tungsten impurity transport based on the drift-kinetic equation

A global kinetic simulation model of collisional impurity transport is developed for evaluating the radial particle flux of tungsten impurity in the edge region of a tokamak plasma. Here, the plasma including the impurity and the background ion is presupposed to be quasi-steady. The simulation model is based on the drift-kinetic equation of the impurity affected by the friction force and the thermal force, which were formulated in the previous study (Homma et al 2016 Nucl. Fusion 56 036009). The model is implemented in a drift-kinetic δf simulation code. We find that the magnetic drift term in the drift-kinetic equation causes the 'global effect' on the impurity transport. Here, the global effect means that the solution δfz of the drift-kinetic equation (and also the radial particle flux) on a magnetic flux surface is influenced by the values of the solution δfz all over the edge region.