Numerical simulation studies on negative hydrogen ion source for uniformity of H− ion beam

Based on the full three-dimensional Particle-in-Cell/Monte Carlo algorithm(PIC/MCC), two special form of multi-peak magnetic field configuration, external magnetic filter and tent-shaped filter, were analyzed respectively, their influences on electronic energy distribution were compared. The simulation results show that they all can confine diffusion of particles and can extract negative hydrogen ions, their electronic energy distributions are basically similar, presenting double energy state, both of them are consistant with plasma discharge basic mechanism; the former is stronger in confining diffusion of particles, is significantly better able to produce more particles, but the latter can efficiently prevent electronic drift caused by inhomogeneous longitudinal magnetic field, leading to more uniform spatial distribution of negative hydrogen ions. Results of simulation are consistent with those from the foreign experiment.