Droplet Emission in a 1 ATM DC Glow Discharge with Liquid Anode: Mechanism and Analysis

Abstract

The interaction between plasma and liquid can provide chemically reactive species useful for many applications, though it is limited by the mass transport of species and their generation from the plasma-liquid interaction. The emission of aerosol droplets from the liquid cathode discharge due to the sheath electric field is widely found [1] - [3] while only limited studies explore droplet emission in liquid anode configuration [4] . In this work, we present detailed observations of droplet emission from the interface into the plasma in a glow discharge with a liquid anode. These droplets’ size and speed are found highly coupled suggesting the interfacial bursting gas bubbles as the production mechanism [5] which can greatly enhance the mass transport of liquid species into the plasma. For validation, we mechanically excite droplet emission through gas injection to initiate interfacial rupturing. After the emission event, droplets will evaporate or abruptly explode thus introducing the electrolyte ions into the gas phase. Here we report on spectroscopically observed species of tracer molecules from the droplets originating in the liquid phase. This finding highlights another mechanism for discharge maintenance and mass transport and suggests an approach to dispersing plasma-activated liquid into gas phase.