大气压沿面型介质阻挡放电光电特性实验和模拟研究

发布时间：2018-06-02 22:16

本文选题：沿面放电 + 放电模式　；参考：《大连理工大学》2016年博士论文

【摘要】：与传统的体相介质阻挡放电相比,沿面型介质阻挡放电更容易产生大面积等离子体层,并可以有效控制边界层气流分布,近年来在材料表面处理、等离子体流动控制、生物医学等领域表现出良好的应用前景。目前,放电模式转换机理和均匀性控制是沿面型介质阻挡放电研究中的两个重要方向。本文通过发射光谱、高速图像采集和数值仿真的方法对大气压空气中沿面放电的模式转换和均匀性等进行了研究。主要研究内容和结论如下：1.建立了一套大气压沿面型介质阻挡放电装置和光学诊断系统,设计了一个延时仅为10ns的同步触发控制系统,用于实时触发ICCD相机以捕捉瞬态放电过程。2.利用发射光谱技术和电流电压探测技术,研究了不同放电参数对发射光谱、电子激发温度、转振温度的影响及其空间分布规律。结果表明,电子激发温度沿轴向放电间隙变化不大,而沿径向最大值出现在暴露电极边缘。随着峰值电压升高,氧原子的电子激发温度和氮分子的转振温度均随之增大。3.利用ICCD高速相机对大气压空气沿面型介质阻挡放电的径向发展和模式转换过程进行了研究,观察到在正、负向电压阶段呈现出两种不同的放电模式,即丝状放电和弥散放电。利用时空分辨光谱测量的方法比较了丝状放电模式和弥散放电模式的发射光谱和转动温度,并分析了两种放电模式发生转换的原因。结果表明,丝状放电通道内的高能电子数密度大于弥散放电；随着丝状放电向弥散放电的转换,氮分子的转动温度减小；介质板表面积累的带电粒子以及表面二次电子发射,是导致正、负向电压阶段放电不对称性的主要原因。4.通过提取阈值后统计图像的像素点,对放电区域的面积进行了检测。同时,提出了一种利用数字图像处理技术中的灰度频率分布曲线来判定放电均匀性的方法,并讨论了激励频率、气体成分、气速、介质材料和厚度对沿面放电均匀性的影响。结果表明,本实验条件下电源频率对沿面放电均匀性的影响较小；惰性气体的加入有利于均匀放电的形成；气速的增加对丝状放电有一定的抑制作用；介电常数较大的陶瓷作为阻挡介质时放电均匀性较好,介质厚度的减小可以有效减弱丝状放电的发展。5.利用大气压空气沿面放电二维流体力学模型,对介质表面电荷密度的周期演变过程及电场强度的时空分布进行了详细分析,验证了一个电压周期内放电的不对称性,并模拟了激励电压、介质材料及电极配置对空气中沿面放电的影响。结果表明,放电区域中的电子雪崩导致初始电场分布发生改变；在电子密度最大位置处场强增大,反向电压阶段电子数密度最大可达3.6×10。6 m-3；最大电子密度随电压峰值的增大而增大,具有较高电子密度的区域也随之扩大。介质板二次电子发射系数的增加有效的减小了气隙击穿电压。滑动型沿面放电结构有利于产生大面积等离子体层。
[Abstract]:Compared with the traditional bulk dielectric barrier discharge, the dielectric barrier discharge along the face type is more likely to produce a large area of plasma layer, and can effectively control the distribution of air flow in the boundary layer. In recent years, it has shown good application prospects in the fields of material surface treatment, plasma flow control, biomedicine and other fields. The uniformity control is the two important direction in the study of the surface dielectric barrier discharge. This paper studies the mode conversion and uniformity of the discharge along the surface of atmospheric pressure air through the emission spectrum, high speed image acquisition and numerical simulation. The main contents and conclusions are as follows: 1. a set of atmospheric pressure along the face type dielectric resistance is established. A synchronous trigger control system with time delay of only 10ns is designed to trigger a ICCD camera to capture transient discharge process in real time..2. uses emission spectrum technology and current voltage detection technology to study the influence of different discharge parameters on the emission spectrum, electron excitation temperature, and vibration temperature and its space. The results show that the electron excitation temperature varies little along the axial discharge gap, and the maximum value along the radial direction appears at the edge of the exposed electrode. With the increase of the peak voltage, the electron excitation temperature of oxygen atom and the transfer temperature of nitrogen molecules increase with the.3. ICCD high-speed phase machine. There are two different modes of discharge in the positive and negative voltage stages, that is, filamentous discharge and dispersion discharge. The firing and rotation temperatures of filamentous discharge mode and dispersion discharge mode are compared by means of space-time resolution spectroscopy, and two kinds of discharge modes are analyzed. The results show that the number density of high energy electrons in the filamentous discharge channel is larger than the dispersion discharge, and with the conversion of the filamentous discharge to the dispersion discharge, the rotational temperature of the nitrogen molecules decreases; the charged particles accumulated on the surface of the dielectric plate and the two electron emission on the surface lead to the asymmetry in the positive and negative voltage stages. The main reason for.4. is to detect the area of the discharge region by extracting the pixel points of the image after extracting the threshold value. At the same time, a method to determine the uniformity of discharge is proposed by using the gray frequency distribution curve in the digital image processing technology. The excitation frequency, the composition of the gas body, the gas velocity, the dielectric material and the thickness of the discharge are discussed. The results show that the influence of the power frequency on the uniformity of discharge along the surface is less; the addition of inert gas is beneficial to the formation of uniform discharge; the increase of gas velocity has a certain inhibitory effect on the filamentous discharge; the dielectric thickness is better and the dielectric thickness is better when the dielectric constant is larger. The reduction of the filamentous discharge can effectively reduce the development of the filamentous discharge.5. using the two-dimensional hydrodynamic model of the atmospheric pressure air discharge. The periodic evolution of the charge density on the surface of the medium and the spatial and temporal distribution of the electric field intensity are analyzed in detail. The asymmetry of the discharge in a voltage cycle is verified, and the excitation voltage and dielectric material are simulated. The effect of the electrode configuration on the discharge in the air along the surface shows that the electronic avalanche in the discharge region causes the change of the initial electric field distribution, the maximum electron density at the maximum electron density and the maximum electron density in the reverse voltage phase can reach 3.6 * 10.6 M-3, and the maximum electron density increases with the increase of the voltage peak, which is higher. The area of the electron density also expands. The increase of the two electron emission coefficient of the dielectric plate reduces the air gap breakdown voltage effectively. The sliding surface discharge structure is beneficial to the production of large area plasma layer.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O461.2

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