Analysis of H atoms in a negative ion source plasma with the non-equilibrium electron energy distribution function

In negative ion sources for the neutral beam injection, it is important to calculate H atom flux onto the plasma grid (PG) surface for the evaluation of H^- production on the PG surface. We have developed a neutral (H ₂ molecules and H atoms) transport code. In the present study, the neutral transport code is applied to the analysis of the H₂ and H transport in a NIFS-RD ion source in order to calculate the flux onto the PG surface. Taking into account non-equilibrium feature of the electron energy distribution function (EEDF), i.e., the fast electron component, we have done the neutral transport simulation. The results suggest that the precise evaluation of the EEDF, especially in the energy range 15 eV < E < 30 eV is important for the dissociation rate of H₂ molecules by the electron impact collision and the resultant H atom flux on the PG.