A mathematical model is developed to calculate the flux and average energy of fast neutrals in a glow discharge based on the charge transfer model used to describe the energy distribution of ions. According to this model the average energy and relative distribution functions of both fast atoms and ions are found to be independent of pressure. Using experimental values found in the literature it is found that the fast atom flux is at least twice as large as the ion flux, but with an average energy similar to the ions. The sputter erosion of the cathode is therefore probably caused mainly by fast atom bombardment.

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