Numerical model of the radio-frequency magnetic presheath including wall impurities

Abstract

Here, we present a numerical fluid plasma model able to capture the enhanced sputtering yield from the Faraday Screen and the Plasma-Facing Components of an Ion Cyclotron Resonance Heating antenna in a fusion machine. The model is a one-dimensional phase-resolved representation of a rectified radio frequency sheath in a magnetic field at an angle with respect to the material surface; the momentum transport of both ions and impurities is computed in the model. The sputtering behavior of the impurities coming off from the wall is obtained from the plasma-material interaction code Fractal-Tridyn. This study analyzes a range of magnetic angles and wave frequencies to parametrically investigate their effect on the energy-angle distributions of the impacting ions and sputtered impurities. Finally, an estimate of the impurity fluxes and of the gross-erosion rate is provided and compared with experimental data available in the literature.