Microdischarge dynamics of volume DBD under the natural convection airflow

Abstract

The dielectric barrier discharge (DBD) at ambient air conditions exhibits discrete structure and contains thin microdischarge plasma filaments. Understanding the formation, self-interaction, and dynamics of such filaments is crucial towards the generation of uniform diffuse-like DBD in air, and also for the study of the memory effects and self-organized complex patterns. In this paper, the impact of natural convective flow, driven by the temperature gradient between self-heated discharge cell electrodes and ambient air, on the collective dynamics of microdischarges was studied in parallel-plate volume dielectric barrier discharge for the different geometrical arrangements. The horizontal arrangement corresponds to the parallel direction of discharge propagation and convective flow, while in the vertical arrangement buoyancy flow transverse to the discharge propagation column. For the horizontal arrangement, the randomly directed motion of microdischarges was observed. While at the vertical arrangement of the discharge cell, the buoyancy flow initiates the directed motion of the microdischarges following the gas flow. The continuous self-heating of the barrier electrodes during the DBD operation leads to a larger thermal gradient and increasing in the microdischarge channels. The larger thermal gradient results in a more pronounced directed motion of microdischarges with a higher velocity. The velocity of convective flow in the discharge gap was estimated by the simulation and compared with the mean velocity of MD channels obtained by the particle image velocimetry method.