Generation of Non-Equilibrium Plasma in the Gliding Arc Discharge

研究了滑动弧光放电在平面和同轴两种几何结构中产生的等离子体参数，特别是在平衡到非平衡转变点附近的等离子体参数。在平行于气流的平面内滑动的空气是基本情况；圆柱形滑动弧形结构增加了独立于外部磁场控制的切向速度。通过与电压-电流测量同步的光学成像来确定电弧传播速度、几何形状、电场和功率输入。有关等离子体条件的附加信息可通过光谱分辨成像、微波干涉测量和红外光谱分析获得。伴随而来的理论研究集中在平衡到非平衡转变的动力学机制上。在热电离和非平衡电离机制都很重要的情况下，对激发粒子和带电粒子的动力学进行了模拟。确定了过渡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型，它提供相对较高的电子密度、电流和功率(热等离子体的典型)以及相对较低的温度和较高的电场(冷非平衡等离子体的典型)。滑动弧光放电在发散电极之间的气流中运动，包含了大气压热弧到非平衡放电的周期性自触发转变。在这个转变中，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.