Discharge characteristics of a brush-shaped argon plasma plume driven by a direct-current voltage

Abstract

A stable plasma plume in brush shape is generated with fairly large area in the ambient air at atmospheric pressure through using argon as the working gas and a direct-current (DC) excited line-plate discharge device. The discharge characteristics of the brush-shaped plume are investigated by optical method. Results show that both the light emission and the current signal are periodically pulsed despite that the discharge is excited by the DC power supply. The light emission frequency is investigated through a photomultiplier tube, and it is found that the discharge frequency increases with increasing the applied voltage or the gas flow rate. Spatially resolved measurements are conducted for the light emission from the plasma plume along the ground electrode and the gas flow, respectively. Results indicate that the uniform plume is composed of micro-discharges, which appear stochastically in time along the line electrode. Along the gas flow direction, the microdischarge propagates in the method of plasma bullets in a high velocity. The optical emission spectrum from the plume is detected by a spectrometer, and the molecular vibrational temperature is calculated based on the discharge spectrum. It is found that the molecular vibrational temperature increases with increasing the voltage or decreasing the gas flow rate.