Morphology evolution of an atmospheric pressure glow discharge initiated in the air gap between a liquid cathode and a needle anode

Self-deformation has been observed for an atmospheric pressure diffuse discharge initiated in the air gap between a needle anode and a water cathode, which undergoes a morphology scenario from a cone, an axially symmetric horn, to a rectangular horn as time elapses. During the self-deformation process, pH value and electric conductivity of the water cathode vary with time. Moreover, electrical measurements indicate that applied voltage and discharge current are time-invariant for the conical discharge, while periodically pulsed for the other two discharges. This may suggest different formation mechanisms of them. Hence, fast photography is implemented by a high-speed video camera and an intensified charge coupled device. Results indicate that the diffuse discharges with different morphologies belong to a glow discharge regime. Among them, the conical discharge is composed of stationary micro-discharge, and the horn-shaped discharges consist of moving micro-discharge. Moreover, the axially symmetric horn is a self-rotating version of the rectangular horn. Furthermore, the rectangular horn originates from the swing of a micro-discharge filament like a pendulum motion. Finally, qualitative explanations are given for the experimental phenomena mentioned above.

Automated summary

This study investigates self-deformation of an atmospheric pressure diffuse discharge initiated between a needle anode and a water cathode, showing a morphological transition from a cone to asymmetric shapes over time. The pH value and electrical conductivity of the water cathode vary during this process. The electrical measurements indicate that the different discharge morphologies may have different formation mechanisms, with conical discharge showing time-invariant behavior while the other two discharges exhibit periodic pulsing. Visual results show that the different discharge morphologies belong to a glow discharge regime, with each type consisting of stationary or moving micro-discharges.