大气压沿面介质阻挡放电等离子体特性研究

发布时间：2018-08-23 19:46

【摘要】：沿面介质阻挡放电(Surface Dielectric Barrier Discharge,SDBD)等离子体产生技术由于放电空间受限制较小,结构简单,动态响应快,可以在介质表面产生面积大且较为均匀的等离子体层,避免了电弧的产生,并具有较高的功率密度,还会产生种类繁多的活性粒子,例如臭氧(O3)、氧原子(O)、双氧水(H2O2)、羟基(OH)等以及它们的激发态粒子,在空气动力学、生物医学以及环境保护等领域有着广阔的应用前景,是近年来的研究热点。目前,国内外对沿面介质阻挡放电及其应用的研究尚处于探索阶段,对其放电特性的影响因素缺乏规律性认识。因此开展不同参数下沿面介质阻挡放电特性的研究,对于推动其应用具有重要的理论意义和工程价值。本文搭建了大气压空气沿面介质阻挡放电产生装置和光电特性检测平台,可以实现放电电压和电流波形等电学参数测量,以及发光图像和发射光谱等光学特性诊断。并基于放电的物理过程和实验结果,分别建立了正弦波交流电源与纳秒脉冲电源作用下等离子体激励器集总参数等效电路模型,通过实验和电路仿真,对大气压沿面介质阻挡放电进行研究,主要包含以下内容：系统地研究了纳秒脉冲电源作用下沿面介质阻挡放电的基本特性,并进一步分析了不同纳秒脉冲电源重复频率作用下,激励器电极对称性、背面电极封装以及对称电极电源接线方式(HV-GND和GND-HV)对沿面介质阻挡放电伏安特性、沉积能量、传输电荷、N2 (C3nu→B3∏g)及N2+(B2∑u+→X2∑g+,0-0, 391.4nm)谱线强度、N2(C3∏u)振动温度与转动温度的影响。得到了如下结果：随着脉冲重复频率增加,沉积能量与传输电荷减小,对应的发射谱线强度出现明显的上升,N2(C3∏u)转动温度增加,振动温度下降。与非对称激励器相比,对称激励器结构对应的放电起始时刻早,具有较高的电流值、沉积能量、传输电荷、N2(C3∏u)振动温度和转动温度和发射光谱强度。背面电极封装后发射光谱强度增强,N2(C3∏u)振动温度与转动温度增加,封装有利于提高能量利用效率。由于极性效应,HV-GND对应的放电起始时刻晚于GND-HV形式,但是具有较高的电流峰值、沉积能量、传输电荷、N2(C3∏u)振动温度和转动温度。对比研究了正弦波电源作用下沿面介质阻挡放电伏安特性、放电功率和传输电荷、N2 (C3∏u→B3∏g)及N2+(B2∑U+→X2∑g+,0-0,391.4nm)谱线强度、N2(C3nu)振动温度和转动温度等参数的特点,并给出了随着电源频率的变化,激励器电极对称性、背面电极封装以及对称电极的电源接线方式(HV-GND和GND-HV)对上述等离子体参量的影响。得到的主要结论包括：与纳秒脉冲电源作用下SDBD等离子体特性相比,正弦波作用下SDBD对应的N2(C3nu)转动温度较高,但N2(C3nu)振动温度低,放电电流幅值远低于同等条件下纳秒脉冲放电电流。两种电源作用下发射光谱组成相同。频率的增加有利于放电的加强,正弦波电源作用下激励器电极对称性、背面电极封装对放电参数的影响与纳秒脉冲电源规律一致,但由于正弦波为交流电源,因此HV-GND和GND-HV两种电源对应的SDBD放电等离子体参数变化不大。在正弦波电源作用下沿面介质阻挡放电实验平台的基础上,研究了引入氩气气流之后伏安特性、放电图像、发射光谱特性、N2(C3∏u)振动温度和转动温度的变化以及氮分子的激发和电离过程。进一步分析了加入氩气之后N2 (C3∏u→ B3∏g,0-0,337.1nm)、N2+(B2∑u+→X2∑g+,0-0,391.4nm:)以及Ar I (2P1→ 1S2,750.39nm)发射谱线强度、N2(C3 ∏u)振动温度和转动温度等参数空间分布特点。深入探讨了改变氩气流量、管距、电源电压幅值以及频率对放电等离子体特性参数的影响。结果表明,氩气引入之后,放电强度和均匀性明显增加,产生了稳定的大面积放电等离子体,N2(C3∏u)转动温度升高,有利于增加动量传递效率,提高气流诱导速度。空间测量结果表明：谱线强度、转动温度在中心处最强,且随着到极板边缘距离的减少而减弱；N2(C3∏u)振动温度的变化与转动温度相反。另外,随着氩气流量增加,放电强度先增加后减弱,N2(C3∏u)转动温度升高,加入氩气之后N2(C3∏u)振动温度先下降,之后随流量增加先增加后减小并趋于稳定,电子激发温度受流量影响较小；随着管距的增加,放电减弱,发射光谱强度、放电功率、电子激发温度以及N2(C3∏u)转动温度出现了大幅下降,但N2(C3∏u)振动温度增加；增加电源电压幅值和频率,谱线强度增加,N2(C3∏u)转动温度、放电功率以及电子激发温度增加,但对N2(C3∏u)振动温度的影响比较小。以非对称结构沿面介质阻挡放电等离子体激励器为研究对象,基于放电的物理过程和实验结果,分别建立了正弦波电源与纳秒脉冲电源作用下等离子体激励器集总参数等效电路模型,通过拍摄高速放电图像,估测了等离子体几何尺寸,借助matlab/simulink软件,联立波尔兹曼方程求解器,求解基尔霍夫电压方程、电子连续性方程,估算两种电源分别作用下电流、平均电子密度和电子温度、气隙电压、介质表面电压等等离子体特性参数随时间的变化规律。得出的结论主要包括：使用可变电阻表示等离子体放电的过程,减少了开关函数,可实现电子密度和电阻推算,有利于对电路进行阻抗匹配,提高电源效率。正弦波交流源作用下的仿真发现,给定电源条件下,平均电子密度和电子温度最高可达1.01×1016m-3和6.1eV,电阻的最小值为0.5MΩ,容抗为8.99GΩ。电阻、容抗随着电流密度的增大非线性减小,电子温度略有增加。单极性纳秒脉冲电源作用下,存在反向放电,电子温度与电子密度分别为2.7×1018m-3和8.5eV,均高于正弦波电源作用的情况。电源斜率对放电有重要的影响,随着电压上升率增加,第一次放电的电流增大。放电时刻提前,但是对应的第二次放电电流略有减小,下降率的增加则对应着第二次放电电流幅值的增加,第一次放电的电流则略有减小。
[Abstract]:Surface Dielectric Barrier Discharge (SDBD) plasma generation technology can produce a large and uniform plasma layer on the dielectric surface because of its small discharge space constraints, simple structure and fast dynamic response, avoiding the generation of arcs, high power density and variety. Various active particles, such as ozone (O3), oxygen (O), hydrogen peroxide (H2O2), hydroxyl (OH) and their excited state particles, have been widely used in aerodynamics, biomedicine, environmental protection and other fields, and have been the research hotspot in recent years. In the exploratory stage, the factors affecting the discharge characteristics are not regularly understood. Therefore, it is of great theoretical and engineering significance to study the characteristics of dielectric barrier discharge along the surface with different parameters for promoting its application. Based on the physical process and experimental results of discharge, the equivalent circuit models of lumped parameters of plasma actuator under the action of sine wave alternating current power supply and nanosecond pulse power supply are established respectively. The experiments and circuit simulation are carried out. True, the study of atmospheric surface dielectric barrier discharge mainly includes the following contents: The basic characteristics of surface dielectric barrier discharge under the action of nanosecond pulse power supply are systematically studied, and the electrode symmetry, back electrode packaging and symmetrical electrode power supply under the action of different repetition frequency of nanosecond pulse power supply are further analyzed. The effects of wiring modes (HV-GND and GND-HV) on the voltage-ampere characteristics, deposition energy, transfer charge, N2 (C3nu_B3_g) and N2 + (B2_u +X2_g +, 0-0, 391.4 nm) spectral intensity, N2 (C3_u) oscillation temperature and rotation temperature of surface dielectric barrier discharge (DBD) were investigated. Compared with the asymmetrical exciter, the symmetrical exciter has a higher discharge starting time, higher current value, deposition energy, transmission charge, N2 (C3_u) vibration temperature and rotational temperature, and emission spectrum intensity. Because of the polarity effect, the discharge initiation time of HV-GND is later than that of GND-HV, but it has higher peak current, deposition energy, transmission charge, N2 (C3_u) vibration temperature and rotation temperature. The voltage-ampere characteristics, discharge power and transmission charge, N2 (C3_u_B3_g) and N2 + (B2_U+X2_g+, 0-0, 391.4 nm) spectral line strength, N2 (C3nu) oscillation temperature and rotational temperature were investigated under sinusoidal wave power supply. The main conclusions are as follows: compared with the plasma characteristics of SDBD under nanosecond pulse power supply, the rotational temperature of N2 (C3nu) corresponding to SDBD under sinusoidal wave is higher, but the vibrational temperature of N2 (C3nu) is lower, and the discharge current amplitude is much lower. Under the same conditions, the emission spectra of nanosecond pulsed discharge current are the same. The increase of frequency is beneficial to the enhancement of discharge. The electrode symmetry of the actuator under sinusoidal wave power supply is good. The influence of back electrode packaging on discharge parameters is consistent with that of nanosecond pulsed discharge power supply. The parameters of SDBD discharge plasma corresponding to GND-HV power supply have little change. Based on the experimental platform of dielectric barrier discharge along the surface under the action of sinusoidal wave power supply, the voltammetric characteristics, discharge image, emission spectrum characteristics, N2 (C3_u) vibration temperature and rotational temperature, as well as the excitation and sum of nitrogen molecule are studied. The spatial distributions of N2 (C3_u_B3_g, 0-0, 337.1 nm), N2 + (B2_u +X2_g+, 0-0, 391.4 nm:) and Ar I (2P1_1S2, 750.39 nm) emission line strength, N2 (C3_u) vibration temperature and rotation temperature are further analyzed. The results show that the discharge intensity and uniformity increase obviously after the introduction of argon, a stable large area discharge plasma is produced, and the rotational temperature of N2 (C3_u) increases, which is conducive to increasing momentum transfer efficiency and airflow induced velocity. The dynamic temperature is the strongest at the center and decreases with the decrease of the distance to the edge of the plate; the change of N2 (C3_u) vibration temperature is opposite to the rotational temperature. In addition, with the increase of argon flow rate, the discharge intensity increases first and then decreases, and the rotational temperature of N2 (C3_u) increases. With the increase of tube spacing, discharge decreases, emission spectrum intensity, discharge power, electron excitation temperature and N2 (C3_u) rotation temperature decrease significantly, but N2 (C3_u) vibration temperature increases; with the increase of voltage amplitude and frequency, spectral line intensity increases, N2 (C_u) vibration temperature increases. 3_u) rotational temperature, discharge power and electron excitation temperature increase, but the effect on N2 (C3_u) vibrational temperature is relatively small. Based on the physical process of discharge and experimental results, plasma ionization under the action of sinusoidal wave power supply and nanosecond pulse power supply is established respectively. The lumped parameter equivalent circuit model of the daughter exciter is used to estimate the plasma geometry size by taking high-speed discharge images. With the help of matlab/simulink software and simultaneous Boltzmann equation solver, Kirchhoff voltage equation and electron continuity equation are solved to estimate the current, average electron density and electron temperature under the action of two power sources respectively. The main conclusions are as follows: using variable resistance to represent the process of plasma discharge, reducing the switching function, realizing the calculation of electron density and resistance, facilitating the impedance matching of the circuit, improving the efficiency of power supply. The simulation results show that the maximum average electron density and temperature can reach 1.01 *1016m-3 and 6.1eV, the minimum resistance is 0.5M, the capacitance reactance is 8.99G. The capacitance reactance decreases nonlinearly with the increase of current density, and the electron temperature increases slightly. The electron temperature and electron density are 2.7 *1018m-3 and 8.5eV, respectively, which are higher than those of the sinusoidal power supply. The slope of the power supply has an important effect on the discharge. With the increase of the voltage rise rate, the current of the first discharge increases, the discharge time is advanced, but the corresponding second discharge current is slightly reduced, and the decrease rate increases correspondingly with the second discharge current. The current of the first discharge decreases slightly when the amplitude of secondary discharge current increases.
【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O461;O53

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