Discharge characteristics analyses of filament-arc ion sources for neutral beam injector by a primary electron orbits calculation code

The arc discharge characteristics of bucket-type negative and positive hydrogen ion sources for neutral beam injectors were studied by simulations and experiments. We calculated the orbits of primary electrons emitted from cathode filaments to obtain the spatial distributions of ionization points of H2 gas molecules. Simulation results for a negative ion source agreed well with the experimental results in which the spatial distribution of plasma parameters differs markedly according to the filament position. The operation efficiencies were quantified and their dependence on magnetic field configurations was discussed for a positive ion source. (author)