Influence of gas flow on argon microwave plasma jet at atmospheric pressure

Many kinds of an atmospheric-pressure plasma jet have been developed and used for widespread applications such as a surface treatment and modified. This study focused on the argon atmospheric-pressure microplasma jet generated by discharging of RF power of 2.45 GHz microwave. The plasma jet shows sensitivity to surrounding environment: pressure, temperature and gaseous species. It is therefore absolutely imperative that a nature of atmospheric-pressure plasma jet should be understood from a point of fluid dynamics. This study, therefore, focused on the interrelationship between the plasma jet and the working gas. Motion of the plasma jet and the working gas was evaluated by velocity measurement and fast photography. As a result, the unsteady sinusoidal waving motion in the radial direction of a torch was observed. Advection velocity of the plasma in just downstream region of the torch exit increases with the supplying flow rate, and the velocity ratio is in the range of 0.75–0.87.