Role of ions (N2+, N+) in the optical emission in nitrogen glow discharge plasma

Intensity distribution of optical emission caused by collisions between ions (N2+, N+) and nitrogen neutral ground-state molecular and the role of ions (N2+, N+)in the optical emission of nitrogen glow discharge plasma are investigated by a combined Monte Carlo model with electrons and the heavy particles. The various impact excitations and optical emissions produced by ions (N2+, N+) distribute in the cathode dark space and the light intensities gradually increase towards the cathode, and total intensities increase with the discharge voltage. Relative to impact excitations and emissions caused by electron, a secondary intensity maximum near the cathode is produced by the collisions between ions (N2+, N+) and molecule N2, and the effect of atomic ions N+ on the impact emission can be stronger than the molecular ions. When the voltage is rather low, the emission caused by the ions collisions can be disregarded. The simulating results offer a good explanation for the experimental data of optical emission spectroscopy under two typical kinds of N2 glow discharge and provide reference evidences for spectroscope data analysis in plasma diagnosis. (authors)