A post-processing method to simulate the generalized RF sheath boundary condition

¹ Lodestar Research Corporation, Boulder, Colorado, 80301, USA
² Kyushu Institute of Technology, Iizuka, Fukuoka, 820-8502, Japan

^* Corresponding author: jrmyra@lodestar.com

Published online: 23 October 2017

Abstract

For applications of ICRF power in fusion devices, control of RF sheath interactions is of great importance. A sheath boundary condition (SBC) was previously developed to provide an effective surface impedance for the interaction of the RF sheath with the waves. The SBC enables the surface power flux and rectified potential energy available for sputtering to be calculated. For legacy codes which cannot easily implement the SBC, or to speed convergence in codes which do implement it, we consider here an approximate method to simulate SBCs by post-processing results obtained using other, e.g. conducting wall, boundary conditions. The basic approximation is that the modifications resulting from the generalized SBC are driven by a fixed incoming wave which could be either a fast wave or a slow wave. The method is illustrated in slab geometry and compared with exact numerical solutions; it is shown to work very well.