Modeling of Plasma Streamers Guided by Multi-Ring Electrodes in Atmospheric Pressure Plasma Jets

In atmospheric pressure plasma jets (APPJs), placing ring electrodes on the outer side of the capillary tube is an efficient way to ignite the plasma discharge and simultaneously assist to lead streamer/ionization wave to propagate inside and outside the dielectric tube. The streamer characteristics in APPJs, such as length, shape, and propagation speed inside the tube, heavily depend on the electric field built by the electrodes. To study the streamer propagation characteristics, needle-to-multi-ring electrode configurations are simulated by a 2-D fluid model. By placing a series of ring electrodes, the gradient of potential inside the dielectric tube determines the intensity of discharge, streamer behaviors, and plume formation. Proper arrangement and polarity of ring electrodes are essential for accelerating streamer propagation. By connecting the multi-ring electrode with positive and negative voltage alternatively, it may ignite discharge directly between adjacent ring electrodes, and the discharge mode seems to transform from a streamer discharge to a typical dielectric barrier discharge.