Influence of discharge voltage on the length of atmospheric argon plasma jet

Abstract

In order to widely apply the high concentration of active substances in plasma jets in sterilization, material modification, environmental protection, etc It is necessary to continuously increase the length of the jet in the external environment of atmospheric pressure under certain conditions, to increase the contact area between the jet and the action object, and to better utilize the effect of plasma. In this demonstration, a needle-ring electrode argon plasma jet device was utilized. By measuring the discharge voltage during the discharge process and capturing images of the discharge, the effect of discharge voltage on plasma jet length was studied. At an argon volume flow rate of 30 l min−1, an electrode spacing of 80 mm, and a discharge voltage of 20.5 kV, a jet length of 81.96 mm in the surrounding air was produced. The results indicate that as the discharge voltage increases, the morphology of the plasma jet changes proportionately; as the discharge voltage increases, the jet morphology changes from a small, neutral discharge to a jet with a needle-like shape, and then to a violent ‘jump’ at the end of the plasma jet; correspondingly, the plasma jet length increases with the discharge voltage, exhibiting an overall trend of first increasing and then stabilizing, but the rate of increase changes from rapid to flat; the plasma jet length increases in the process of two peaks, and after reaching the second peak, it stabilizes and no longer grows significantly; the magnitude of the excitation voltage is proportional to the distance between the two electrodes under the initial test conditions, and the plasma excitation voltage grows with increasing distance between the electrodes while the argon gas flow rate remains constant; the excitation voltage produced by the plasma jet exceeds the minimum voltage necessary to sustain the plasma discharge.