Atmospheric negative corona discharge using Taylor cone as a liquid cathode

Abstract

We examined the characteristics of atmospheric negative corona discharge using a liquid needle cathode. As a liquid needle cathode, a Taylor cone with conical shape was adopted. A micronozzle was filled with liquid, and a plate electrode was placed above the nozzle. By applying a dc voltage between electrodes, a Taylor cone is formed. To change the liquid property, we added sodium dodecyl sulfate to reduce the surface tension, sodium sulfate to increase the conductivity, and polyvinyl alcohol to increase the viscosity, in distilled water. Liquids with a high surface tension such as pure water could not form a Taylor cone. When we reduced the surface tension, a Taylor cone was formed and a stable corona discharge was observed at the tip of the cone. When we increased viscosity, a liquid filament protruding from the solution surface was formed and corona discharge was observed along the filament at a position 0.7–1.0 mm above the tip of the cone. Increasing the conductivity resulted in the higher light intensity of the corona and the lower corona onset voltage. Using a Taylor cone, different types of corona discharge were observed by changing the property of the liquid.

Electrohydrodynamic stability of a plasma-liquid interface

“…Another EHD effect, the deformation of a liquid surface into a Taylor cone, has recently been used to form the cathode of a corona discharge. 20 This paper investigates the EHD stability of a plasmaliquid interface with a linear perturbation analysis. Melcher's stability criterion is found to apply to short-wavelength perturbations of the surface.…”

Simulated dynamics of a plasma-sheath-liquid interface*

“…The recent experiments of Shirai et al have imaged the formation of corona discharges on the surface of a Taylor cone which are accompanied by the ejection of fine droplets from its tip [27,28]. The formation of droplet plumes is also reported by Schwartz et al [29].…”

“…The cones formed in Shirai's experiments also lead to the formation of droplets and detection of current pulses at the upper plate electrode. These current pulses, which are displayed in [28], figure 4(a), are accompanied by a sharp increase in the light intensity from the discharge. The numerical simulation in figure 2 provides one possible explanation for these current pulses; the ejection of a burst of droplets followed by the collapse of the protrusion over a timescale of around 10μs which roughly matches the duration of the experimental current bursts.…”

“…Various compounds were dissolved in the water: sodium dodecyl sulphate to lower its surface tension and sodium chloride to increase its conductivity. When the applied voltage reached 4.52kV the liquid surface deformed into a Taylor cone [28] and produced a fine jet of droplets. Assuming typical electron temperatures and densities of 1eV and 10 19 m −3 , for a humid air discharge [2], gives a normalised sheath potential drop of f »e k T 4500 w B e and the Debye length as 2.4μm.…”

Plasma and Aerosols: Challenges, Opportunities and Perspectives

“…will be mutual and the collaboration will provide new perspectives and tools to the cited domains (e.g., enhanced evaporation and introduction of reactive species in fuel droplets to increase flame control and reduce pollutant production). There were a few studies, which investigated the interactions of the sprayed charged aerosol droplets and the discharge, especially with respect to the space charges and ion mobility effects [56][57][58], or even studies that intentionally employed these complex interactions, e.g., for water treatment or surface decontamination [59][60][61]. Valuable information, methods, techniques and models can be extracted from these studies or reviews [54,62] and used for a deeper investigations of plasma-aerosol interaction.…”