2016 年 11 巻 p. 2406044
In order to enhance the H− surface production in hydrogen negative ion sources, it is important to increase the density of the H atoms dissociated from H2 molecule and the resultant atomic flux towards the surface of the plasma grid. In this paper, the effect of the Electron Energy Distribution Function (EEDF) on the dissociation of H2 in Linac4 H− source has been studied using Electromagnetic Particle In Cell (EM-PIC) simulation with Monte Carlo method for Collision Processes (MCC). It has been shown that the rate coefficient of dissociation reactions can be enhanced in the lower H2 gas pressure regime, while the H atom production rate becomes larger in the higher pressure regime. It is suggested that the optimal H2 gas pressure to maximize the H atom production is determined by the balance of rate coefficient and the H2 density.
