High-voltage electrode optimization towards uniform surface treatment by a pulsed volume discharge

A V Ponomarev,M S Pedos,Y I Mamontov,S V Ponomarev,S V Scherbinin

doi:10.1088/1742-6596/652/1/012035

Abstract

In this study, the shape and material of the high-voltage electrode of an atmospheric pressure plasma generation system were optimised. The research was performed with the goal of achieving maximum uniformity of plasma treatment of the surface of the low-voltage electrode with a diameter of 100 mm. In order to generate low-temperature plasma with the volume of roughly 1 cubic decimetre, a pulsed volume discharge was used initiated with a corona discharge. The uniformity of the plasma in the region of the low-voltage electrode was assessed using a system for measuring the distribution of discharge current density. The system's low-voltage electrode - collector - was a disc of 100 mm in diameter, the conducting surface of which was divided into 64 radially located segments of equal surface area. The current at each segment was registered by a high-speed measuring system controlled by an ARM™-based 32-bit microcontroller. To facilitate the interpretation of results obtained, a computer program was developed to visualise the results. The program provides a 3D image of the current density distribution on the surface of the low-voltage electrode. Based on the results obtained an optimum shape for a high-voltage electrode was determined. Uniformity of the distribution of discharge current density in relation to distance between electrodes was studied. It was proven that the level of non-uniformity of current density distribution depends on the size of the gap between electrodes. Experiments indicated that it is advantageous to use graphite felt VGN-6 (Russian abbreviation) as the material of the high-voltage electrode's emitting surface.

Highlights

A pulsed volume discharge is of great interest for the creation of significant volumes of lowtemperature plasma within gaps up to tens of centimeters [1]
Processes in the pulsed volume discharges are similar to processes in the classical stationary glow discharge, where cathode and anode fall off potentials, Faraday dark space and positive column exist
The volume discharge possesses some significant differences from the classical glow discharge

Summary

Introduction

A pulsed volume discharge is of great interest for the creation of significant volumes of lowtemperature plasma within gaps up to tens of centimeters [1]. Processes in the pulsed volume discharges are similar to processes in the classical stationary glow discharge, where cathode and anode fall off potentials, Faraday dark space and positive column exist. The volume discharge possesses some significant differences from the classical glow discharge. One of them is that to materialize such a discharge a pre-ionization of gas is needed, which can be performed with auxiliary discharges such as DBD, corona, spark. Another difference is that this type of discharge is not stationary. One more difference is its specific peak power which can exceed 1 MW/cm, that significantly exceeds the similar characteristics of a classical glow discharge.

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