An experimental study on plasma characteristics of a capillary atmospheric pressure plasma device using argon/air mixture gas stream

In this work, plasma jet devices have been developed on the basis of atmospheric pressure glow discharges. In the previous reports (CEIDP 2008 and 2009), discharge characteristics of plasma jet in which pure Ar and He gas were used as the working fluid was reported, respectively. Those results provide a suggestion for simplification of an atmospheric pressure plasma generation device. This paper discuss an experimental study on atmospheric pressure plasma jet using Ar and dry air mixed gas for the purpose of generating some useful radicals for surface treatments. The present device is constructed as a coaxial arrangement with a dielectric capillary tube (silica glass) and a discharge electrode (copper tube) where the silica glass tube is covered with a grounded discharge electrode (copper foil). When the dielectric barrier discharge (DBD) occurred along the inner surface of dielectric tube, the glow-like plasma of Ar and air mixture gas is generated and the ionized gas stream effuses as a plasma jet to air environment. Regarding the plasma diagnoses, a magnetic probe method and an emission spectroscopy method is applied to a quantitative analysis. The emission spectroscopy and plasma density characteristics be discussed as a function of air admixture to Ar gas.