The energy distributions of major ions in the cathode zone of a strongly abnormal nitrogen DC glow discharge

Energy distributions of N+ and N-2(+) ions bombarding the aluminium cathode of a glow discharge at high current densities (few mA cm(-2)) have been calculated and compared with experimentally determined values. The results show a high proportion of N+ compared to (N-1(+) + N-2(+)) which are characteristic of a nitrogen discharge and arise from the small value of the cross-section for the process N-1(+) + N-2 --> N-1+ N-2(+). Energy distributions calculated with the analytical model based on the Boltzmann equation are close to the experimental distributions measured by mass spectrometry in the higher range of ion energy (normalised to anode cathode voltage). This agreement is closer at higher pressures (similar to 0.1 mbar) when the condition of plane geometry of a discharge is more closely satisfied than at lower pressures (few 0.01 mbar). (C) 1998 Elsevier Science Ltd.