Experimental evaluation for plasma diagnoses of gas-jet type atmospheric pressure plasma

In this work, a device of atmospheric pressure plasma source was experimentally investigated and constructed as a coaxial arrangement with a discharge electrode and a dielectric tube of 6 mm in an inner diameter. The plasma source at the atmospheric pressure condition was formed into a noble gas (He) jet exposed to dielectric barrier discharges on pulse high-voltage applications. The plasma ignited by the barrier discharge was observed as a plasma bullet which was traveled from a nozzle of the dielectric barrier discharge tube to the room air. Since the electron temperature and the electron density were required in the plasma diagnoses, the important plasma parameters were quantitatively evaluated by an optical emission spectroscopy method and a magnetic probe method. The plasma density was evaluated from the traveling current density and the traveling velocity of plasma bullets along the noble gas jet axis, which were monitored by a magnetic probe. For analyzing the plasma generation mechanism, this paper presents the electrical discharge characteristics, plasma emission photograph, the plasma density and the electron temperature of plasma bullets. The fundamental characteristics of the electron temperature and the electron density are discussed in detail from the atmospheric pressure plasma conditions as a function of the experimental parameter such as the applied voltage and the gas flow rate.