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开发了氮空心阴极放电PIC/MC二维自洽模型。研究了N2传统空心阴极向微空心阴极放电转变过程中电势和电场的变化。结果表明,不同尺寸的空心阴极放电的电势及电场分布规律几乎类似,但空心阴极孔径减小且气压增加时,电场近似线性增加;典型微空心阴极电场比传统空心阴极放电电场约大3个量级;微空心阴极放电产生的电子,氮分子离子和氮原子离子的密度比传统空心阴极放电约大3个量级,且微空心阴极放电中,N2+密度比N+密度大8倍以上。     

Electromagnetic interaction between local surface plasmon polaritons and an atmospheric surface wave plasma jet

We analyze the electromagnetic interaction between local surface plasmon polaritons （SPPs） and an atmospheric surface wave plasma jet （ASWPJ） in combination with our designed discharge device. Before discharge, the excitation of the SPPs and the spatial distribution of the enhanced electric field are analyzed. During discharge, the critical breakdown electric field of the gases at atmospheric gas pressure and the surface wave of the SPPs converted into electron plasma waves at resonant points are studied. After discharge, the ionization development process of the ASWPJ is simulated using a two- dimensional fluid model. Our results suggest that the local enhanced electric field of SPPs is merely the precondition of gas breakdown, and the key mechanism in maintaining the discharge development of a low-power ASWPJ is the wave-mode conversion of the local enhanced electric field at the resonant point.     

The influence of the axial heterogeneity of the plasma of high-frequency torch discharge on its electrodynamic characteristics

Measuring results for axial distribution of gas temperature of high-frequency torch discharge burning in the air at atmospheric pressure are presented. The distribution of electric field over the discharge axis was calculated based on the model of discharge in the form of heterogeneous electric line of finite length. It is shown that the experimentally observed linear character of electric field change along the discharge axis is conditioned by its axial heterogeneity.     

Self-organization of the channel structure of a nanosecond diffuse discharge in a wire-plane electrode system

The results of an experimental study of the spatial structure of a high-voltage diffuse discharge in a wire-plane electrode system are presented. Self-organization of the discharge current channels into regular cells is observed in the plane perpendicular to the electric field vector. The dependences of the structural parameters of the discharge in centimeter-sized gaps on the interelectrode distance are studied at air pressures within the range 220–760 torr. Self-organization of the discharge structure is explained in terms of the electric interaction among charges of the diffuse channel heads during bridging of the gap.     

Experimental study of the discharge glow structure in the initial phase of a nanosecond breakdown of an insulating gap

The diffuse phase of high-voltage nanosecond atmospheric-pressure discharges in insulating gaps with a highly nonuniform electric field has been studied experimentally with the purpose of developing methods for protecting power supply equipment from natural and man-caused overvoltages. The structure of the discharge glow in 6- to 12-cm rod-plane gaps has been investigated for five configurations of the rod cathode. It is found that the discharge can exist in different forms and that the occurrence of one or another type of discharge is probabilistic in character. The electric characteristics of the discharge have been studied as functions of the electrode gap length for two types of cathode that provide the preferential development of volume and multichannel discharges. It is shown that the main factors governing the shape of the discharge glow are the distribution of the electric field near the cathode in the voltage growth phase and the dynamics of the accompanying discharge processes.     

Effect of relative humidity on current–voltage characteristics of monopolar DC wire-to-plane system

This paper deals with the DC monopolar corona discharge in wire-to-plane geometry under variable humid air conditions. The classical formulas of Townsend commonly used for the current–voltage characteristics were used to determine the various corona parameters for the both polarities of the corona discharge. A circular biased probe has been adapted to the plane and is used to measure the ground plane current density and electric field during the monopolar corona discharge. A new approach to the problem of corona discharge in transmission system has been described in this paper. The effect of varying the humidity and wires diameter is also investigated. The values of the electric field and the current density are maximum beneath the corona wire and decrease when moving away from them and the current–voltage characteristics follow the quadratic Townsend's law. The experimental results show that the monopolar corona discharge is strongly affected by the air humidity. The current density and the electric field are measured and compared with the computed values. The agreement between the calculated values and those obtained experimentally is satisfactory. The per unit electric field and current density are also represented by a unique function.     

Partial discharge-induced crack growth in dielectric materials

Partial discharge(PD) of an air-filled semi-permeable crack in a dielectric material is studied based on the streamer-type discharge mechanism to explore the effects of applied mechanical-electric fields on crack growth.Within the frame of two-dimensional deformation,the electric field inside the crack is first derived by taking the crack deformation into account.Then,the effects of electric field before PD are discussed through considering the contribution of the induced electric field inside the deformed ...     

微空心阴极放电时空特性

为了揭示微空心阴极放电的放电机理,利用流体模型研究了矩形微空心阴极放电的时间和空间分布特性。在氩气环境下计算得到了压强为1.3×10~4Pa时电流、电势、电场、电子和离子密度等随时间的发展变化。结果表明,整个放电过程分为四个阶段,即预放电阶段、电场由轴向向径向转换阶段、电流缓慢增长向空心阴极效应过渡阶段和稳态放电阶段。稳态放电时出现明显的空心阴极效应,阴极位降区存在很高的径向电场和较高的电子平均能量,而负辉区径向电场很弱,电子平均能量较低,电子和离子密度峰值出现在负辉区,二者数值基本相等,而在阴极位降区离子密度远高于电子密度。     

Electric ignition energy evaluation and the energy distribution structure of energy released in electrostatic discharge process

Ignition energy is one of the important parameters of flammable materials, and evaluating ignition energy precisely is essential to the safety of process industry and combustion science and technology. By using electric spark discharge test system, a series of electric spark discharge experiments were conducted with the capacitor-stored energy in the range of 10 J, 100 J, and 1000 J, respectively. The evaluation method for energy consumed by electric spark, wire, and switch during capacitor discharge process has been studied respectively. The resistance of wire, switch, and plasma between electrodes has been evaluated by different methods and an optimized evaluation method has been obtained. The electric energy consumed by wire, electric switch, and electric spark-induced plasma between electrodes were obtained and the energy structure of capacitor-released energy was analyzed. The dynamic process and the characteristic parameters(the maximum power, duration of discharge process) of electric spark discharge process have been analyzed. Experimental results showed that, electric spark-consumed energy only accounts for 8%–14% of the capacitor-released energy. With the increase of capacitor-released energy, the duration of discharge process becomes longer, and the energy of plasma accounts for more in the capacitor-released energy. The power of electric spark varies with time as a damped sinusoids function and the period and the maximum value increase with the capacitor-released energy.     

Influence of wire mesh electrodes on the volume and surface characteristics of dielectric barrier discharge of atmospheric pressure helium

The dielectric barrier discharge of helium in a 6 mm gap at atmospheric pressure was studied. In this paper, the influence of electric field distribution on the uniformity of DBD is analyzed theoretically and verified by experiments. The experimental results show that the mesh electrode produces a local enhancement effect by affecting the electric field and then produces corona discharge, which provides seed electrons for the subsequent discharge process. The effects of mesh diameter and size on discharge uniformity and stability are analyzed, the electrode structure parameters are optimized, the method of a segmented electrode is proposed, and the discharge process and charge distribution are studied. The electrical diagnosis results of plasma technology show that the segmented mesh electrode reduces the breakdown voltage of DBD and increases the charge deposition.     

基于D-dot传感器的弓网离线放电瞬态电场时域测试方法

弓网离线放电电磁辐射具有瞬态、宽频带的特性,可使用D-dot传感器对其进行时域瞬态电场测量,但在对传感器所测微分信号积分还原时,存在信号恢复失真问题严重。搭建了包含脉冲电场发生装置和测量装置的瞬态电场时域波形还原系统,开展了基于D-dot传感器的去直流、数值积分、消除趋势项以及系统辨识低频补偿在内的瞬态电场时域波形测试方法的研究,利用该方法测试了不同电压下弓网离线放电电磁辐射的电场时域波形。理论与实验结果表明:本文所提出的方法能准确、稳定地还原弓网离线放电所辐射瞬态电场的原始时域波形,还原信号与实测微分信号的主要频率分量均在7.5 MHz,二者的相关系数达到93%以上。     

Longitudinal DC electric discharge in a supersonic air flow

A longitudinal dc electric discharge in a submerged high-pressure supersonic air jet is described. Photographs of the discharge are provided. The experimental voltage across the discharge gap and the discharge current are given for two resistances of the resistor that limits the discharge current over a certain range of the discharge channel length along the air flow. The current-voltage discharge characteristic is provided at a constant discharge length. The main discharge characteristics are obtained from a comparison of the experimental and theoretical results calculated on the basis of the simplest model.     

氦气空心阴极放电动力学过程的模拟研究

利用流体模型模拟研究了氦气空心阴极放电的时空动力学过程,计算得到了不同放电时刻电子和亚稳态氦原子密度、电势、电场、基态电离速率和分步电离速率等的时空分布特性。特别是讨论了亚稳态原子和分步电离对于放电的影响。结果表明,随着电流的增长,放电处于五个不同的放电模式:第一阶段电流上升非常缓慢,为汤生放电模式,带电粒子密度、亚稳态原子密度和径向电场均很弱;第二阶段电流迅速上升,放电模式由汤生放电向空心阴极放电过渡,带电粒子密度、亚稳态原子密度和径向电场迅速增强;第三阶段达到准稳态阶段,放电电流增长速度变缓,形成了明显的阴极鞘层结构;第四阶段为空心阴极效应形成阶段,向稳态阶段过渡;第五阶段为稳态放电阶段。研究结果同时表明,亚稳态氦原子和分步电离在放电的初始阶段对于放电的发展作用较弱,在前三阶段中,电子的产生以基态电离为主。随着放电的发展,由亚稳态原子引起的分步电离对新的电子产生的作用逐渐接近并超过基态电离,对总电离的贡献率越来越高。     

基于麦克斯韦电磁场理论的神经元动力学响应与隐藏放电控制

钙、钾、钠等离子在细胞内连续泵送和传输时产生的时变电场不仅会影响神经元的放电活动,而且会诱导时变磁场去进一步调节细胞内离子的传播.根据麦克斯韦电磁场理论,时变的电场和磁场在细胞内外的电生理环境中会相互激发而产生电磁场.为了探究电磁场影响下的神经元放电节律转迁,本文在三维Hindmarsh-Rose(HR)神经元模型的基...     

Numerical studies of atmospheric pressure glow discharge controlled by a dielectric barrier between two coaxial electrodes

The glow discharge in pure helium at atmospheric pressure, controlled by a dielectric barrier between coaxial electrodes, is investigated based on a one-dimensional self-consistent fluid model. By solving the continuity equations for electrons, ions, and excited atoms, with the current conservation equation and the electric field profile, the time evolution of the discharge current, gas voltage and the surface density of charged particles on the dielectric barrier are calculated. The simulation results show that the peak values of the discharge current, gas voltage and electric field in the first half period are asymmetric to the second half. When the current reaches its positive or negative maximum, the electric field profile, and the electron and ion densities represent similar properties to the typical glow discharge at low pressures. Obviously there exist a cathode fall, a negative glow region, and a positive column. Effects of the barrier position in between the two coaxial electrodes and the discharge gap width on discharge current characteristics are also analysed. The result indicates that, in the case when the dielectric covering the outer electrode only, the gas is punctured earlier during the former half period and later during the latter half period than other cases, also the current peak value is higher, and the difference of pulse width between the two half periods is more obvious. On reducing the gap width, the multiple current pulse discharge happens.     

Optical breakdown in a CO2 spark afterglow

The threshold for optical breakdown in the presence of an electric discharge in CO₂ is measured as a function of the time delay between the electric spark and the laser pulse. The results are qualitatively explained by the cascade theory with the initial conditions determined by the dynamics of the discharge.     

Wave dynamics of electric explosion in solids

A mathematical model of an electric explosion is developed that consistently describes the expansion of the explosion channel with regard to the parameters of the discharge circuit of a high-voltage pulse generator, radiation, and propagation of stress waves in a solid. The dynamics of conversion of the stored energy to a wave and the formation of mechanical stresses due to electric explosion in a solid immersed in a liquid are considered. In the context of electro-discharge destruction of hard materials, the resulting stress field and the relationship between the discharge circuit parameters and characteristics of the wave are analyzed and the most efficient discharge modes are determined.     

介质材料二次电子发射特性对微波击穿的影响

以介质填充的平行板放电结构为例,本文主要研究了介质填充后微波低气压放电和微放电的物理过程.为了探究介质材料特性对微波低气压放电和微放电阈值的影响,本文采用自主研发的二次电子发射特性测量装置,测量了7种常见介质材料的二次电子发射系数和二次电子能谱.依据二次电子发射过程中介质表面正带电的稳定条件,计算了介质材料稳态表面电位与二次电子发射系数以及能谱参数的关系.在放电结构中引入与表面电位相应的等效直流电场后,依据电子扩散模型和微放电中电子谐振条件,分别探讨了介质表面稳态表面电位的大小对微波低气压放电和微放电阈值的影响.结果表明,介质材料的二次电子发射系数以及能谱参数越大,介质材料的稳态表面电位也越大,对应的微波低气压放电和微放电阈值也越大.所得结论对于填充介质的选择有一定的理论指导价值.     

Experimental study of electric discharge treatment of nanodiamond particles in water

A novel type of high voltage pulsed electric discharge in water flow in a Venturi tube is proposed. The influence of the novel discharge on sizes and properties of nanodiamond particles has been studied. Experiments were carried out in water media with purified detonation nanodiamonds made impure by non-diamond carbon material. The ability of high voltage pulsed electric discharge in water to modify nanoparticle conglomerates in water solution and to relieve spherically shaped nanodiamond conglomerates from the initial mixture with non-diamond material can be seen. Prolonged treatment of the suspension made it possible to relieve primary nanodiamond crystals from conglomerates. Formation of ordered and unordered structures from primary (3?C5 nm) nanodiamond crystals has been observed. Study of the electric discharge in water was carried out at the pressure region from atmospheric down to 0.02 atm to reproduce conditions which are typical for the discharge in the Venturi tube in liquid flow and different gap lengths. Two ??types?? of discharge behavior depending on the geometry of the discharge system and other external parameters have been observed. Characteristics that are critical for understanding the behavior of the discharge in the Venturi tube in water flow have been investigated.     

介质面刻槽抑制二次电子倍增蒙特卡罗模拟

利用蒙特卡罗方法,针对介质表面刻槽抑制二次电子倍增的实验现象,进行了数值模拟研究。给出了二次电子倍增动力学方程、刻槽边界条件、二次电子初始能量与角度分布以及发射率分布关系;讨论了槽深、槽宽对二次电子倍增的抑制效果,以及同一刻槽结构对不同微波场强度和频率的二次电子倍增抑制能力;分析了双边二次电子倍增区域。数值研究结果表明:增加槽深、缩短槽宽可以抑制二次电子倍增;同一刻槽结构,更易于抑制高频场、场强较低或较高下的二次电子倍增;刻槽尺寸的选择还应避开双边二次电子倍增区间。将数值模拟结果与相关实验现象进行了对比,吻合得较好。