Monte-Carlo Study Based on Real Coordinates for Perpendicularly Injected High-Energy Ions in the LHD High-Beta Plasma

Abstract

We present a study of ions produced by the perpendicular neutral beam in the high-beta plasma of Large Helical Device (LHD) that uses the Monte-Carlo code based on orbit following in real coordinates with Coulomb collisions. For no neutrals outside the plasma, the results indicate that there are remarkable differences in the distribution functions that depend on whether the loss boundary is set on the vacuum vessel wall or on the last closed flux surface (LCFS). Also, for finite neutral density n_H = 10¹⁸ m⁻³, we find that the minor radial profile of the distribution function slightly differs from that for the infinite neutral density case, which corresponds to the loss boundary being set at the LCFS.