Numerical study on discharge modes in atmospheric dielectric barrier discharges and their transition excited by the medium frequencies

Abstract

The recent experimental observation shows that in the medium frequency range (300 kHz–3 MHz), there are two discharge modes, namely the Ω mode and hybrid mode. In this paper, a fluid model is explored to study the characteristics of these two discharge modes and their transitions. The numerical data indicate in the Ω mode the conduction current density is very low and the plasmas are mainly generated in the central region of gas gap, while the Ohmic heating takes place at the same region. For the hybrid mode, the ion density is very high in the sheath region, and the electrons are accelerated and produced in the sheath region, which are very similar to the characters of glow discharges in the low frequency region; meanwhile, a bulk plasma region with very high density is also formed in the center of gas gap, which is characterized by the α mode in the high frequency range. The mode transition among the glow discharge mode, hybrid mode and α mode is also investigated by varying the excitation frequency but with a fixed applied voltage. This simulation will deepen the understanding of mode transition in atmospheric discharges controlled by dielectric barriers for the whole excitation frequency range.