Diagnostics of parameters by optical emission spectroscopy and Langmuir probe in a discharge of Ar/N2/CH4 ternary mixture

A low-pressure DC plasma discharge sustained in a 85.0%N2-12.0%Ar- 3.0%CH4, 82.3%N2-13.7%Ar- 4.0%CH4 and 79.6%N2-15.4%Ar- 5%CH4 ternary mixtures is studied. These plasmas were generated in the total pressure range of 1.0 to 10.0 Torr, power of 7 W and 50 l/min flow rate gas. The diagnostic has been made by optical emission spectroscopy (OES) using a spectrometer. The species observed were: N2; N2+; CH+; CN; C2; H and Ar. We present the behavior of the bands and lines intensities as a function of the pressure and concentration of Ar, N2 and CH4 gases. Also, we display more quantitatively the ratios of intensities of N+2 (391.44 nm), CN (392.08 nm), and H (486.13 nm) to that of the N2 (337.13 nm) as function of pressure. The ratios show an almost constant behavior as a function of the pressure. Being the CH/N2 ratio more highest and H/N2 ratio the lowest one.