Monte Carlo Study Based on a Real Coordinate System for Tangentially Injected High-Energy Particles in the Large Helical Device

Abstract

A new Monte Carlo code based on particle tracing using real coordinates has been developed to properly treat the re-entering particles that repeatedly pass in and out of the last closed flux surface (LCFS). The particle loss due to the charge-exchange reaction has also been taken into account in this code. We apply this new code to the analysis of high-energy particles produced by tangential neutral beams (NBs) of the large helical device (LHD). It is confirmed that reasonable solutions of distribution functions are obtained for particles produced by the tangential-NBs. It is also confirmed that the effect of the particle orbit and the charge-exchange loss on the distribution function is properly included. The shapes of the distribution functions of particles, produced by the tangential-NBs in two temperature cases (1 keV and 0.1 keV), are the same. It is found that the re-entering particles play an important role in the analyses of the distribution function of particles produced by the NBs.