The influence of Ar metastable atoms on the discharge structure in rf glow discharges is investigated in Ar and N2 mixed gas experimentally and theoretically. The purpose of adding a small amount of N2 is to control the metastable density. Time- and space-resolved optical emission spectroscopy is applied to investigate the behavior of high-energy electrons. The density profile of Ar metastables in Ar and N2 mixture is estimated from the optical emission intensity of the second positive band of N2, which results from the energy transfer from Ar metastables to N2 molecules. The decreases of current and optical emission intensity, as well as the Ar metastable density with increase of N2 ratio, are observed. It is concluded that ionization through metastables is one of the important processes in increasing the plasma density, especially at higher pressures.
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