A novel cold plasma jet generator based on atmospheric dielectric barrier capillary discharge

Summary form only given. An easily-run plasma generator is presented to generate a novel kind of atmospheric cold plasma millimeter jet. The jet is achieved in several kinds of gases at atmosphere pressure, such as Ar, He and N₂, in a capillary quartz dielectric barrier discharge (DBD) system powered by a sinuous power source with frequency of 33 kHz. There are two different discharge regions in the generator. The filament discharges in the DBD gap, the first discharge region, are found to be transited into diffusion discharges or glow-like discharges by the flowing gas through the DBD gap and then a plasma jet is formed near the outlet of the capillary, the second discharge region. The coexistence of the two discharge regions and the flow of the working gas are two basic requisites for generating the cold plasma jet. The critical gas flow velocity for the jet formation is determined to be 3-8 m/s for different gases by a static Pitot tube probe. The jet range for a special gas can be changed by varying the gas flow velocity, while the jet range for different gases varies a lot and the helium jet takes the longest range of about 44 mm when the helium flows at a velocity of about 20 m/s. Beyond the velocity limit of 20 m/s for laminar helium flow, the jet of helium plasma becomes torrent and unstable and its range turns shorter