OH and O radicals production in atmospheric pressure air/Ar/H2O gliding arc discharge plasma jet

Atmospheric pressure air/Ar/H2O gliding arc discharge plasma is produced by a pulsed dc power supply.An optical emission spectroscopic (OES) diagnostic technique is used for the characterization of plasmas and for identifications of OH and O radicals along with other species in the plasmas.The OES diagnostic technique reveals the excitation Tx ≈ 5550-9000 K,rotational Tr ≈ 135002700 K and gas Tg ≈ 850-1600K temperatures,and electron density ne ≈ (1.1-1.9) × 1014 cm-3 under different experimental conditions.The production and destruction of OH and O radicals are investigated as functions of applied voltage and air flow rate.Relative intensities of OH and O radicals indicate that their production rates are increased with increasing Ar content in the gas mixture and applied voltage.ne reveals that the higher densities of OH and O radicals are produced in the discharge due to more effective electron impact dissociation of H2O and O2 molecules caused by higher kinetic energies as gained by electrons from the enhanced electric field as well as by enhanced ne.The productions of OH and O are decreasing with increasing air flow rate due to removal of Joule heat from the discharge region but enhanced air flow rate significantly modifies discharge maintenance properties.Besides,Tg significantly reduces with the enhanced air flow rate.This investigation reveals that Ar plays a significant role in the production of OH and O radicals.