On the influence of energy transfer efficiency on the electron energy distribution function in HF sustained rate gas plasmas: experimental and numerical study

In this paper the influence of the energy transfer efficiency on the elastic part of the electron energy distribution functions in HF sustained plasmas is investigated theoretically as well as experimentally. The gases considered are the rare gases argon, neon and helium. The different shapes of the observed electron distribution functions in their low-energy part are related to he energy transfer rate, which may be strongly energy-dependent via the momentum transfer collision frequency. The importance of the Ramsauer minimum of argon for the formation of the shape of its electron energy distribution is pointed out. The different shapes observed for the distribution functions in helium and neon are interpreted in terms of the less energy-dependent energy transfer rates, due to the less pronounced variation of their momentum transfer cross sections.