Volumetric Plasma Discharge in a Coaxial Electrode Configuration Using Repetitively Pulsed Nanosecond Discharges

Abstract

Transient plasma discharges can be created in different electrode geometries and the use of a coaxial electrodes can assist in initiating ignition at multiple points at the same time to create volumetric ignition. The current study investigates discharge formation in a coaxial electrode in quiescent, atmoshpheric and non-reacting conditions. This is the first systematic study to understand the behavior of such a discharge as a function of different pulse parameters like pulse width (40-110 ns), repetition frequency (1-50 kHz) and input voltage (14-20 kV). Additionally, the polarity of the central electrode was changed between positive and negative. An intensified ccd camera was used to visualize the discharge formation. The exposure of the camera is set to capture 500 discharges in a single frame. The discharges were found to behave differently for positive and negative polarity discharges. The positive polarity discharge tends to form a strong arc and spins around the outer cylinder which is confirmed using a high speed camera. The negative polarity discharges form a uniform streamer discharge for most of the pulse parameters. The current study has provided an initial understanding of the dynamics of plasma discharges in a coaxial electrode.