二维对称结构纳秒脉冲介质阻挡放电数值模拟

Modeling of the Two-dimensional Nanosecond SDBD Discharge with Symmetry Electrodes

为具体分析放电过程中电场强度、电子密度、平均电子能量及鞘层的变化规律,通过简化化学反应动力学模型以及采用全时域漂移-扩散模型方程,对N2-O2混合气体的二维平行电极纳秒脉冲介质阻挡等离子体放电的发展演化过程进行数值模拟。计算结果发现:放电从电极处开始发展形成约化场强约为5×10-19 V?m2的强电场,高电压电极附近形成0.2 mm的鞘层区域,鞘层边缘存在数密度为1.6×1019 m-3的薄电子层,且其边缘分层结构与低气压辉光放电鞘层分层结构一致;电子沉积在介质表面,等离子体从强电场中获得的能量使得其在脉冲结束后的余辉过程中继续维持,进而有效地将能量耦合给等离子体。数值模拟结果表明,提出的简化化学反应动力学模型能够有效地模拟复杂的介质阻挡纳秒脉冲放电的物理过程及其各个物理参数的变化规律。

To study the variation of electrical field intensity, electron density, mean electron energy and sheath of surface dielectric barrier discharge （SDBD）, with the reduced chemical kinetics model and the full time-domain drift-diffusion mode, we conducted 2-D simulation of the SDBD plasma formation between parallel electrodes in N2-O2 mixture air at low-pressure under nanosecond impulses. It turns out that during the discharge, there is a strong electric field of about 5×10^-19 V·m^2 from the electrodes, as well as a sheath about 0.2-mm thick near the anode. The edge of the sheath has a thin shell composed of electrons of about 1.6×10^19 m^-3 in number density; its structure of layers is as same as that of the sheath of low-pressure glow discharge. Meanwhile electrons deposit on the surfaces of dielectric barriers and form a strong electric field that provide enough energy to the plasma to sustain it then in the afterglow at the end of pulse, which effectively couples energy to the plasma. The simulation results shows that the simplified chemical kinetics model is ef- fective in simulating the complex physical process of nanosecond-pulse electrical discharges including the variations of multiple physical parameters.