Spectral characteristics of argon and argon-methane plasma obtained in an RF-DBD reactor at low pressure

Abstract

This paper investigates the properties and spectral characteristics of low-temperature argon plasma and argon-methane mixture plasma formed in a high-frequency dielectric barrier discharge (RF-DBD) at various powers and pressures. The experiments were conducted at an argon flow rate of 100 sccm for argon plasma and at a ratio of Ar:CH₄ = 95:5 for argon-methane plasma in the power range from 2 to 12 W and pressures of 0.5 and 1.0 Torr. It is shown that with an increase in the supplied power, the discharge area expands and the intensity of spectral lines increases, which is due to an increase in plasma density and the degree of ionisation. When the pressure increases, there is a decrease in the overall intensity of radiation due to a reduction in the free path length of electrons and an increase in collision losses. The introduction of methane leads to a decrease in the intensity of the spectral lines of molecular nitrogen and hydroxyl radicals (OH) compared to argon plasma, which indicates a redistribution of electron energy in favour of the excitation of argon atoms and active methane particles. The results obtained contribute to a deeper understanding of the physicochemical processes in Ar–CH₄ plasma and open up prospects for the application of RF-DBD discharges in plasma chemistry and materials science.