Electronic and ionic processes and ionic bombardment of the cathode in a DC hydrogen glow discharge

The ionic and electronic reactions occurring in the cathode dark space (CDS) and negative glow (NG) of a hydrogen glow discharge with operating parameters typical of those used in surface treatments are modelled to calculate the angular and energy distributions of the ions incident on the cathode. The self-consistent model comprises three interactive sub-models, two of which are based on Monte Carlo simulations of electrons and positive ions, the third on conservation and mobility equations and is used for the determination of the ions' diffusion current from the NG to the CDS. Where available, reaction cross sections are taken from the literature with estimates being made for those such as H₃⁺ to H⁺ which are not documented. An experimental determination of the energy of H⁺, H₂⁺ and H₃⁺ ions arriving at the cathode of the discharge is described and it is shown that the hydrogen ion currents predicted by the model are in accordance with those measured experimentally.