NaOH对苯胺气液两相介质阻挡放电特性的影响

研究气液两相介质阻挡放电(DBD)的特性,对于深入理解其放电机理、促进其在环保等工业领域中应用具有重要意义。通过电压电流波形和Lissajous图形等电气特性诊断及发射光谱和发光图像等光学特性诊断,研究了液体成分对大气压气液两相DBD放电特性的影响。比较了苯胺和苯胺加NaOH溶液中气液两相DBD放电特性,利用实验结果计算得到放电功率和传输电荷,并结合放电理论对放电机制进行了分析。结果表明,苯胺加NaOH溶液中气液两相DBD,其放电特性与纯苯胺溶液有明显不同,相同电压下其放电电流约为纯苯胺溶液的两倍,其发光强度更强,放电功率和传输电荷更大,且在光谱特性图波长589nm处出现Na原子谱线,NaOH的加入增加了溶液的电导率,同时促进了气相放电强度,使得放电增强。     

放电参数对爆燃模式下同轴枪强流脉冲放电等离子体的影响

同轴枪强流脉冲放电常见有爆燃模式和预填充模式两种放电模式,爆燃模式放电可以得到杂质少、准直性高、输运速度更快的等离子体射流.本实验主要对不同电压及进气量下同轴枪强流脉冲爆燃模式放电的等离子体特性进行了研究.结果表明,在相同放电电压下,进气量少时会有多团等离子体从枪口喷出.随着进气量的增加,同轴枪放电产生的等离子体密度增加,输运速度减小,最终等离子体只有一团从枪口喷出;而在相同进气量下,随着电压的增加,等离子体密度增加,输运速度增大,开始出现有多团等离子体从枪口喷出的现象.产生该现象的原因主要是在放电过程中,当气体持续进入枪底部时,同轴枪底部会产生新的电流通道向前运动,使得在同轴枪出口处观察到了多团等离子体喷出的现象;随着放电电压的增加,在放电过程中回路电流也增加.当电流增加到一定程度时,同轴枪底部就会产生新的电流通道,从而有多个等离子体团从枪口喷出.通过改变充电电容以及对磁探针信号的分析,进一步分析并验证了同轴枪底端多次放电的现象.     

Rate of localized gas discharge etching of silicon

The dependence of the etching rate of silicon on the technological, design, and electrophysical parameters that characterize the glowing conditions and the properties of a localized gas discharge is studied. Experiments are performed at a gas pressure of 104–105 Pa and a discharge gap of 50–500 μm. Emission spectroscopy is shown to be an efficient method for controlling the beginning and the end of localized gas discharge etching of different materials.     

Study on the transition from filamentary discharge to diffuse discharge by using a dielectric barrier surface discharge device

Discharge characteristics have been investigated in different gases under different pressures using a dielectric barrier surface discharge device. Electrical measurements and optical emission spectroscopy are used to study the discharge, and the results obtained show that the discharges in atmospheric pressure helium and in low-pressure air are diffuse, while that in high-pressure air is filamentary. With decreasing pressure, the discharge in air can transit from filamentary to diffuse one. The results also indicate that corona discharge around the stripe electrode is important for the diffuse discharge. The spectral intensity of N电介质 表面放电 扩散放电 发射光谱学dielectric barrier surface discharge, diffuse discharge, optical emission spectroscopyProject supported by the National Natural Science Foundation of China (Grant Nos 10575027 and 10647123), the National Science Foundation of Hebei Province, China (Grant No A2007000134), the Education Department of Hebei Province, China (Grant No 2006106),2006-10-24Discharge characteristics have been investigated in different gases under different pressures using a dielectric barrier surface discharge device. Electrical measurements and optical emission spectroscopy are used to study the discharge, and the results obtained show that the discharges in atmospheric pressure helium and in low-pressure air are diffuse, while that in high-pressure air is filamentary. With decreasing pressure, the discharge in air can transit from filamentary to diffuse one. The results also indicate that corona discharge around the stripe electrode is important for the diffuse discharge. The spectral intensity of N＋ （391.4nm） relative to N2 （337.1 nm） is measured during the transition from diffuse to filamentary discharge. It is shown that relative spectral intensity increases during the discharge transition. This phenomenon implies that the averaged electron energy in diffuse discharge is higher than that in the filamentary discharge.     

高功率脉冲磁控溅射的阶段性放电特征

本文从放电靶电流出发,采用一种新的研究方法,即将靶电流分解为多个代表具体放电特性的特征参数,全面而系统的研究了不同的工作气压条件下,靶电流各特征参数随靶电压的增加而进行的演化.结果发现高功率脉冲磁控溅射技术(HPPMS)放电靶电流在靶电压由低向高增加的过程中,出现靶电流峰值和平台值的交替变化,体现出明显的阶段性放电特征,且不同的放电阶段在不同气压下出现一定的移动,会在测量范围内出现某些放电阶段的缺失.本文还通过等离子体发射光谱对HPPMS放电靶前等离子体测量发现五个不同的放电阶段分别主要对应氩原子、铬原子、氩离子、铬离子和氩、铬高价离子的放电,但不同的放电条件下相邻的阶段会出现一定程度的交叠.     

Characterization of brush type discharge electrodes and impact of enhanced corona discharge on operation of electrostatic precipitators

This project presents the results of investigation of current/voltage characteristics of brush type discharge electrodes (BTDE) in tube type electrostatic precipitators and the effect on operation. Experimental investigations were conducted with discharge electrodes of different wire diameter and different brush diameter. The effect of electrode geometry on current/voltage behavior was recorded. Corona current with brush type discharge electrodes was modeled and compared with experimental data. Brush type discharge electrodes produce an enhanced corona current compared with wire type discharge electrodes. Limited enhanced corona has improving effect on collection efficiency. An adjusted correlation was therefore deduced from experimentally obtained current/voltage data with BTDE.     

介质阻挡放电中电介质参量对放电时间特性的影响

采用介质参量不对称的装置,在大气压氩气介质阻挡放电中,研究了不同电介质温度及不同电介质材料对放电时间特性的影响.实验发现,外加电压较低时,正负半周的放电时间波形没有明显的差别;外加电压较高时,正负半周的放电脉冲个数不同.分析表明,电介质温度以及材料均影响壁电荷的积累,进而使放电特性发生改变. 关键词： 介质阻挡放电 时间特性 壁电荷 介电常数     

大气压氦气介质阻挡放电中的周期一不对称放电实验研究

大气压介质阻挡放电不仅具有对称周期一的放电形式, 还会在一定参数下呈现不对称周期一(AP1)放电. 本文采用具有平行电极结构的介质阻挡放电装置, 分别在气隙宽度1 mm, 3 mm, 7 mm和10 mm下的大气压氦气中进行了一系列放电实验, 研究了气隙宽度和外施电压频率对周期一放电对称性的影响. 实验结果表明: 在较宽的气隙宽度和外施电压频率参数区间内可以观察到显著的AP1放电; 气隙宽度越大越容易产生AP1放电, 同一气隙宽度下外施电压频率较高时则相对更容易观察到AP1放电; 随着气隙宽度增加, 首次击穿即呈现AP1 放电的外施电压频率临界值逐渐减小. 本文的研究初步验证了之前关于气隙宽度对AP1放电影响的数值仿真结果, 由此可以推测AP1放电并不只是由系统参数的不对称引起的, 也很可能是一种在一定的气隙宽度和外施电压频率下系统固有的、内在的高频不稳定放电行为. 关键词： 介质阻挡放电 不对称放电     

Radio emission structure of cloud-to-ground lightning discharge

Cloud-to-ground lightning discharge radio frequency emission is analysed on the base of measurements with high temporal resolution allowed to fully resolve its structure. Discharge radio emission mainly consists of independent random bi-polar pulses. Pulse length, amplitude and interpulse period distributions are studied at different stages of lightning discharge. The significant change of radio frequency emission structure during discharge development is demonstrated.     

接近速度对空气静电放电特性的影响

 通过理论分析和实验测量,研究了导体接近速度对空气放电的影响。理论计算了两导体相互接近时导体的自（互）电容系数、导体电势差、导体电势差随导体间的间隙（放电间隙）的变化率和导体电势差的时间变化率。实验研究了5 kV和10 kV放电电压下放电电流峰值和耦合电压峰-峰值随接近速度的变化关系。接近速度直接决定了空气击穿时导体电势差的时间变化率,同时也就决定了不同速度下的空气放电特性;接近速度影响了火花击穿的时间延迟,从而对空气放电产生了时间效应。     

Different modes of capacitively coupled radio-frequency discharge in methane

Two different modes of capacitively coupled radio-frequency (RF) discharge in methane at gas pressures between 0.01 and 1.00 Torr are examined by numerical simulation based on a combined approach. It is shown that transition between volume-dominated and active-sheath modes is caused by variation of discharge current or gas pressure. Hysteretic behavior is revealed as the discharge current density is varied along the growing-and falling-current branches of the current-density curve. A phase diagram representing the domains of different discharge modes is obtained in wide current and pressure ranges.     

New color-enhancing discharge mode using self-erasing discharge in AC plasma display panel

A new color-enhancing discharge mode using a self-erasing discharge is proposed based on an analysis of the Ne emission mechanism in a Ne-Xe gas mixture. The effects of the new color-enhancing discharge mode produced by a ramped-square sustain waveform on improving the color reproducibility are examined in an alternate current plasma display panel (ac-PDP) filled with a Ne-Xe gas mixture. When the ramped-square sustain pulses are applied at 150 kHz, the color purities of the blue and green visible emissions are both improved, thereby expanding the color gamut area by about 5.4% without reducing the luminance.     

Numerical simulation of a direct current glow discharge in atmospheric pressure helium

Characteristics of a direct current(DC) discharge in atmospheric pressure helium are numerically investigated based on a one-dimensional fluid model. The results indicate that the discharge does not reach its steady state till it takes a period of time. Moreover, the required time increases and the current density of the steady state decreases with increasing the gap width. Through analyzing the spatial distributions of the electron density, the ion density and the electric field at different discharge moments, it is found that the DC discharge starts with a Townsend regime, then transits to a glow regime. In addition, the discharge operates in a normal glow mode or an abnormal glow one under different parameters, such as the gap width, the ballast resistors, and the secondary electron emission coefficients, judged by its voltage–current characteristics.     

脉冲气体放电管特性测量实验

用TDS210型存贮示波器测量了脉冲气体放电管(闪光灯)的放电特性，同时用PIN型硅光电池测量脉冲光的波形，测量了它们之间的延迟，并计算了脉冲气体放电管的动态电阻，讨论了放电过程从触发到结束的物理图象．     

非链式HF激光器SF6气体介质放电特性

采用放电图像拍摄和放电波形测量两种方法研究了放电激励HF激光工作介质SF6气体的放电特性。实验结果表明:SF6气体放电可以分为主放电、剩余电压维持和电弧放电3个阶段。主放电阶段为均匀体放电,电容储能大部分在此阶段沉积于放电等离子体中;剩余电压维持阶段无明显放电;在电弧放电阶段激光器以电弧形式消耗剩余储能。通过对放电波形的分析,获得剩余电压及主放电阶段能量沉积效率随充电电压的变化规律。随着充电电压提高,剩余电压下降,沉积效率逐渐提高。沉积效率最大值对应于主放电与电弧放电相接的时刻。     

介质阻挡放电不同边界放电区域的光谱分析

利用大直径双水电极介质阻挡放电装置,在氩气和空气的混合气体中观察到了相同实验条件下不同边界的放电区域出现不同放电模式的实验现象.其中正方形封闭边界内可形成规则的斑图,而半开放放电区域只能看到随机游走的放电丝.通过采集发射光谱发现封闭边界内激发能较高的几条谱线如696.5,727.3,750.4和772.4nm的相对强度...     

气压对微束射频容性放电模式调制的研究

微束射频容性放电在纳米晶体颗粒等离子体增强气相合成有着潜在的应用前景.本论文利用ICCD、单反相机、高压探头和电流探头等对微束射频容性放电特性进行了实验诊断研究.结果发现:在纯氩气微束射频放电中,随着气压的增加,放电从辉光放电模式向多通道丝状放电模式转换;在99%氩/1%氢混合气体微束射频放电中,丝状放电模式消失,而是从低气压全空间分布的辉光放电模式,到中等气压向轴心收缩的辉光放电模式,最后到高气压的“环状”辉光放电模式;而在纯氢气微束射频放电中,随着气压的增加,放电模式直接从全空间分布的辉光放电模式向“环状”辉光放电模式转换.最后通过射频电场中电子加热、趋肤效应和气体热传导的共同作用解释了产生不同放电模式的物理机制.     

Mechanisms controlling the transition from glow silent discharge tostreamer discharge in nitrogen

Low-energy dielectric-barrier controlled discharges in nitrogen are studied by undertaking electrical measurements to determine mechanisms controlling the transition from glow to streamer-like discharge. The highest and the lowest values of the frequency and the amplitude of power supply voltage leading to a glow discharge have been found dependent on the gas flow and the nature of the surface in contact with the discharge. These boundary values have been related to the criteria necessary for initiating a Townsend breakdown rather than a streamer breakdown commonly observed under such conditions. This implies: (1) that the seed electron density just before the breakdown is high enough to allow the development of numerous small avalanches under a low field avoiding the formation of only one large avalanche mechanism at the origin of the streamer formation; and (2) to let the time for ions issued from the first avalanches to reach the cathode before the electrical field becomes large enough to induce the formation of large avalanches. Practically, the transition from a Townsend breakdown to a streamer breakdown is analyzed from electrical measurements data coupled to the visual aspect of the discharge. Without any gas flow, the obtaining of an atmospheric pressure glow discharge (APGD) is mainly limited by the species etched from the surface in contact with the gas. Indeed, these species can be quenchers of the nitrogen metastable molecules, which are the species at the origin of the formation of seed electrons via the Penning effect. This limitation can be overcome by the use of a laminar gas flow. However, this type of gas flow through the discharge induces a depletion of N₂ metastables and, consequently, influences the electron density at the entrance of the discharge, leading to a tendency on this part of the discharge to transit to a streamer-like one     

大气压He-Ar射频容性放电Ar亚稳态粒子数密度

利用发射光谱法测量大气压He-Ar混合气体射频容性放电中的Ar亚稳态1s5(3s23p54s［3/2］2)粒子数密度。在不同的放电功率和气体组分下测量放电等离子体中的重要参数:气体转动温度、电子激发温度和Ar亚稳态1s5粒子数密度。结果表明:气体温度在不同放电功率及Ar气压在5103 Pa以内时变化不大,范围为300~350 K;电子激发温度随着放电功率的增加而增加,并且在Ar气压为4103 Pa时最大,在放电功率为70 W时达到0.58 eV;1s5粒子数密度随着放电功率以及电子激发温度的增加而增加,在放电功率为70 W、Ar气压为4103 Pa时达到1.53109 cm-3。