Numerical Simulation of Radio-frequency Dielectric Barrier Atmospheric Pressure Glow Discharges
|Keywords||Dielectric barrier discharge Radio frequency glow discharge Numerical simulation Pulse modulation|
Much attention has been paid on atmospheric pressure glow discharges (APGDs) for their wide application scopes, such as surface modification, semiconductor etching, thin film deposition and biological sterilization. APGDs can be generated by electrical excitation with repetition frequency from kilo hertz to mega hertz., Especially with mega hertz excitation, radio frequency (RF) APGDs can be obtained stably due to the trapping of electrons and other active species in the region of discharge bulk.The discharge characteristics of RF dielectric barrier APGDs are mainly affected by the following factors. Firstly, the properties of dielectric barrier, gap size and electrode configuration et al. Secondly, the difference of electrical excitation, such as the waveforms and repetition frequency. Thirdly, environmental influence, the impurity gases, pressure and flow rate are all important to the discharge under atmospheric pressure without airtight chamber. It is difficult to measure the discharge parameters and characteristics experimentally due to the limitation of diagnostics for APGDs. In order to further understand the discharge characteristics and mechanism, the numerical simulation is carried out here for studying.The low-temperature plasma is a complicated system composing of a variety of charged particles, which involves particle dynamics, diffusion and transport equation, Maxwell equations, surface reactions. The fluid model is normally proposed in order to simplify simulation by demonstrating the overall characteristics of discharge. Here, the one-dimensional and two-dimensional dielectric barrier APGDs models are developed to study the discharge characteristics and mechanism. The simulated results show the spatio-temporal evolution of electron, electron energy and electric field, et al to demonstrate the discharge dynamics of dielectric barrier RF APGDs. It is also studied the modulate RF APGDs by pulse modulation, which helps to show the ignition characteristics of RF APGDs. All the simulated results provides a theoretical basis for further in-depth understanding of RF dielectric barrier APGDs, and provides theoretical guidance on the development of uniform and stable RF APGDs with reduced power consumption and gas temperature of plasmas.