Generation of Non-Equilibrium Plasma in the Gliding Arc Discharge

本文研究了滑行弧放电在平面和同轴两种几何形状中，特别是在平衡到非平衡过渡点附近传播时产生的等离子体参数。平行于气流的平面上的滑行空气是基本情况；圆柱滑弧结构增加了切向速度，切向速度由外部磁场独立控制。电弧传播速度、几何形状、电场和功率输入由与电压电流测量同步的光学成像确定。等离子体条件的附加信息是通过光谱分辨成像、微波干涉测量和红外光谱获得的。伴随而来的理论研究侧重于从平衡态到非平衡态转变的动力学机制。在热电离和非平衡电离机制都很重要的条件下，模拟了激发态和带电粒子的动力学。确定了跃迁等离子体中电场和气体温度的临界值，并与实验结果进行了比较。滑动电弧是一种大气压空气放电的混合类型，它提供相对较高的电子密度、电流和功率（典型的热等离子体），同时提供相对较低的温度和高的电场（典型的冷非平衡等离子体）。滑动电弧放电在不同电极之间的气体流动中移动，包含周期性的自触发大气压热电弧向非平衡放电的转变。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。

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.