Oxygen Effects on a $\hbox {He/O}_{2}$ Plasma Jet at Atmospheric Pressure

A plasma jet has been developed that operates using RF power and produces a stable homogeneous discharge of He/O₂ at atmospheric pressure. An optical emission spectroscopy technique was used to observe the electronically excited species at the point 10 mm downstream from the nozzle generated by the He/O₂ plasma jet, and the discharge characteristics for the gas mixture of He/O₂ were studied with a current probe and a voltage probe. The results indicate that there is a relative optimum fraction of O₂ in the He/O₂ gas mixture from 0.5% to 1.5% for the relative larger intensity of the characteristic atomic oxygen line at 777 nm, the root-mean-square (rms) current and rms voltage of the discharge are also more sensitive to oxygen content than to total gas flow.