Generation of Non-Equilibrium Plasma in the Gliding Arc Discharge

本文研究了滑动弧放电在平面和同轴两种几何结构中传播时产生的等离子体参数，特别是在平衡态向非平衡态转变点附近。 在平行于气流的平面中的滑行空气是基本情况;圆柱形滑行弧配置增加了由外部磁场独立控制的切向速度。 电弧传播速度，几何形状，电场，和功率输入确定的光学成像与电压-电流测量同步。 通过光谱分辨成像、微波干涉测量和红外光谱法获得关于等离子体条件的附加信息。 伴随的理论研究侧重于平衡到非平衡转变的动力学机制。 激发和带电粒子的动力学建模的条件下，热电离和非平衡电离机制是重要的。 在过渡等离子体的电场和气体温度的临界值被确定，并比较实验结果。滑动弧是一种混合型的大气压空气放电，提供相对较高的水平的电子密度，电流和功率（典型的热等离子体）沿着与相对较低的温度和高电场（典型的冷非平衡等离子体）。 滑动电弧放电，在发散电极之间的气体流中移动，包含大气压热电弧到非平衡放电的周期性自触发过渡。 在这种转变中，等离子体迅速冷却，而电子密度保持在热等离子体水平上。

This is a study of plasma parameters generated in the gliding-arc discharge propagating in both plane and coaxial geometries , especially near the equilibrium-to-nonequilibrium transition point. The gliding air in the plane parallel to the gas flow is the base case; a cylindrical gliding-arc configuration adds tangential velocity independently controlled by external magnetic fields. Arc propagation velocities, geometry, electric fields, and power inputs are determined by optical imaging synchronized with voltage-current measurements. Additional information on plasma conditions is obtained by spectrally resolved imaging, microwave interferometry, and infrared spectroscopy. A concomitant theoretical study focuses on kinetic mechanisms of the equilibrium-to-nonequilibrium transition. Kinetics of excited and charged particles are modeled under conditions when both thermal ionization and nonequilibrium ionization mechanisms are important. Critical values of the electric field and gas temperature in the transition plasmas are identified and compared to experimental findings.The gliding arc is a hybrid type of atmospheric-pressure air discharge that provides relatively high levels of electron density, current, and power (typical of thermal plasmas) along with relatively low temperature and high electric field (typical of cold nonequilibrium plasmas). The gliding-arc discharge, moving in a gas flow between divergent electrodes, contains periodic self-triggered transitions of atmospheric-pressure thermal arc into a nonequilibrium discharge. In this transition, the plasma cools rapidly while electron density remains on the thermal-plasma level.