大气压氦气同轴双气隙介质阻挡辉光放电研究

为进一步探究大气压流动环境中生成均匀等离子体的条件和机理,本文针对一种新型的针-管同轴双气隙介质阻挡放电结构,采用高频高压交流电源,在大气压下,对流动的氦气进行了气体放电实验。利用高速相机记录了放电演化过程图像,利用示波器测量了电流电压波形,利用光谱仪测量了放电发射光谱,分析了氦气的大气压辉光放电过程。实验结果表明,在该种介质阻挡放电结构中,氦气可实现大气压辉光放电。电流波形在正负半周期存在明显的不对称性,放电主要发生在正半周期。放电产生了激发态的He原子。     

基于质谱法的大气压介质阻挡放电等离子体中O3和N2O组分的测量

为提高介质阻挡放电(DBD)在大气压条件下低温等离子体的产率以及设备的稳定性和可靠性，降低处理成本，提高航天发射废水的降解率，利用四极杆质谱仪设计了一套基于质谱法的大气压DBD等离子体中O₃和N₂O组分测量系统，通过测量等离子体组分和未放电时的大气组分来证实该方法的可行性。结果表明，在101.325 kPa大气压条件下，使用6管同轴介质阻挡放电，在控制电压为200 V时，O₃和N₂O的组分浓度达到最高；在控制电压为200 V,空气流量为7.8 L/min时，O₃的组分浓度达到最高；在空气流量为3.8 L/min时，N₂O的组分浓度达到最高。综上所述，控制电压和空气流量对等离子体组分浓度有较大影响，解决了传统质谱法难以应用于大气压条件下DBD等离子体活性产物测量和强电场对质谱仪干扰的问题。本研究结果在DBD反应器的优化、关键参数的调控和实现大气压DBD在降解航天推进剂废水的工程实际应用方面具有参考价值。     

敞开式离子源和微型气泵集成的微型针-柱放电结构芯片设计与实验分析

采用LIGA(Lithographie,Galvanoformung,Abformung)工艺设计加工了一种微型针-柱放电结构芯片,可实现敞开式离子源和微型气泵的系统集成。此微型放电结构由采用电镀铜加工而成的针电极、上圆柱电极和下圆柱电极组成,针-柱间距有1mm、2mm两种规格。在室温、大气压环境、无外界通入气流的条件下,通过在针-柱电极上加载负直流高压,可产生稳定的气体放电。利用风速计testo 405-V1测量芯片气体放电产生的离子风风速,结果表明针-柱间距为2mm时产生的离子风流速最大,可达0.79m/s。对针-柱间距2mm规格的微型芯片进行乙酸进样电离实验,当针-柱之间产生稳定的电晕放电后,可发现位于芯片出口处已被去离子水润湿的PH试纸变红。此时利用微弱电流检测系统采集电离产生的离子,当放电电压为-3300V时,通过微弱电流采集系统检测到的电流信号可达120pA。采用LTQ XL离子阱质谱仪,对芯片电离丙酮、无水乙醇和乙酸乙酯的离子产物进行检测,所得到的主要物质为质子化单体离子和二聚物离子。放电产生离子风风速以及乙酸的进样和电离实验表明,基于LIGA的微型针-柱结构芯片可实现大气压环境下敞开式离子源和微型气泵的双重功能。     

电源类型对短电弧-电化学复合加工放电凹坑影响研究

放电凹坑大小影响着加工表面形貌的一致性,放电凹坑的凸起高度及凹坑表面的重铸层对加工表面质量有重要影响。文章基于短电弧-电化学复合加工方法,在直流与脉冲两种常用电源类型下对钛合金TC4进行单次放电实验,分析两种电源类型下的短电弧-电化学复合加工单次放电凹坑尺寸及影响规律;结合单次放电凹坑实验所采集到的波形与电弧放电过程仿真模型对电弧放电过程的等离子体放电通道变化进行研究。研究结果发现,直流与脉冲放电凹坑的尺寸与影响规律差异与电弧的断弧方式有关,不同的断弧方式对等离子体放电通道产生影响,直流电弧倾向于通过流体介质运动和极间距离改变进行断弧,而脉冲电弧通过脉冲后沿电压变化和极间距离改变进行熄弧。这两种断弧方式不仅影响了凹坑的尺寸形貌,也影响了断弧后的电化学腐蚀效果。     

基于回归模型的SDBD-PA击穿特性试验研究

近年来,表面介质阻挡放电等离子体激励器（Surface dielectric barrier discharge plasma actuator,SDBD-PA）已经成为流动控制领域的研究热点。为研究SDBD-PA的击穿特性,为SDBD-PA相关研究的参数区间选取提供参考,首先采用控制变量法研究各激励器参数对SDBD-PA击穿电压和放电稳定性的影响,然后选取对击穿电压有影响的激励器参数,基于DOE方法进行试验,使用Isight软件建立二次回归模型并分析激励器参数对击穿电压的影响。研究结果表明,对SDBD-PA击穿电压和放电稳定性有影响的参数包括频率f、电极间隙d₁和激励器长度L;拟合所得三元二次回归模型经验证具有良好的精确度,可作为SDBD-PA击穿电压的预测模型;对SDBD-PA击穿电压影响最大的参数是f,其次为L和d₁;f和L对击穿电压的影响为负效应,d₁对击穿电压的影响为正效应;d₁和f之间以及f和L之间的交互作用对击穿电压也有很大影响,d₁和L之间的交互作用对击穿电压的影响非常小。     

超高功率体放电的形成及其应用

研究了氮气中的高压体(扩散)放电特性,实验中施加的极间隙脉冲电压达数百千伏,持续时间为数纳秒,上升时间为几个纳秒,给出了实验结果.研究了氦气压强为((0.4-2)×105Pa时,从扩散形式到火花放电的放电转换过程.确定了在氮气压强下电流幅度与逃逸电子束电流脉宽的关系.结果表明,导致隙间扩散放电的超短雪崩电子束(SAEB...     

用于介质阻挡放电的占空比可调的电源的研制

为了探究在不同电压频率和幅值的条件下,高压电源发出的方波占空比对所产生的等离子体性质的影响,研制了基于滞回比较器频率在5.4kHz～17kHz、占空比在0～100%可调的高压脉冲电源。提出使用UC4832电源芯片研发用于介质阻挡放电的占空比可调电源的方案,并对所设计电路进行了仿真。同时提出了适用于基于法拉第盘的等离子体检测仪器接口的同心型介质阻挡等离子体发生器的结构。仿真及实验结果表明:所设计的电源及放电装置能稳定产生等离子体,放电强度可调。     

低功率水工质脉冲等离子体推进器的工作特性

为了解决Teflon脉冲等离子体推进器存在的性能低、有污染等问题,设计了以水为工质的脉冲等离子体推进器系统,并研究了它的主要工作指标的能量阈值.分析了水工质脉冲等离子体推进器系统的放电类型形成条件及原因,通过放电电压和电流测试实验,对工作能量阈值进行了实验研究,得到了稳定运行能量对应的储能电容值.实验结果表明:在足够高...     

过电状态下高铁齿轮油失效研究

高铁齿轮箱在用油在过电状态下会提前失效,影响列车的正常运维。通过台架实验模拟高铁齿轮油在过电状态下的失效,探究过电电压和击穿时间与油品的色度、黏度、酸值、生成物、电极损伤之间的对应关系。实验结果表明:在实验设定条件下,临界击穿电压约为1 500 V;在实验加载电压达到2 500 V,击穿次数58次后,油中生成物明显增多;实验电极表面在实验完毕出现少量点蚀剥落。     

针-柱结构敞开式离子源和微型气泵集成系统的放电特性

设计了一种小型针-柱电晕放电结构,实现了敞开式离子源和微型气泵的系统集成。通过数码相机拍摄的针-柱放电图像和示波器记录的特里切尔放电波形,验证了该针-柱结构在没有外界气流、间隙仅2 mm的实验条件下实现了稳定的电晕放电。对针-柱结构电晕放电特性进行了研究,讨论了放电电压、镇流电阻、柱直径大小、针-柱间距等参数对针-柱电晕放电的影响,通过伏安特性曲线分析得出在放电电压为-3 800 V、镇流电阻为10 MΩ、柱直径为4 mm、间距为2 mm的实验条件下,产生的离子风气体流速最大（采用testo 405-V1风速仪测得最大气体流速为1.15 m/s）。该针-柱结构可采用微机电系统（MEMS）工艺加工实现,有望应用于质谱仪、离子迁移谱、高场非对称波形离子迁移谱等便携式分析仪器中,实现敞开式离子源和微型气泵的双重功能。     

Cold plasma brush generated at atmospheric pressure

A cold plasma brush is generated at atmospheric pressure with low power consumption in the level of several watts (as low as 4 W) up to tens of watts (up to 45 W). The plasma can be ignited and sustained in both continuous and pulsed modes with different plasma gases such as argon or helium, but argon was selected as a primary gas for use in this work. The brush-shaped plasma is formed and extended outside of the discharge chamber with typical dimension of 10-15 mm in width and less than 1.0 mm in thickness, which are adjustable by changing the discharge chamber design and operating conditions. The brush-shaped plasma provides some unique features and distinct nonequilibrium plasma characteristics. Temperature measurements using a thermocouple thermometer showed that the gas phase temperatures of the plasma brush are close to room temperature (as low as 42 degrees C) when running with a relatively high gas flow rate of about 3500 ml/min. For an argon plasma brush, the operating voltage from less than 500 V to about 2500 V was tested, with an argon gas flow rate varied from less than 1000 to 3500 ml/min. The cold plasma brush can most efficiently use the discharge power as well as the plasma gas for material and surface treatment. The very low power consumption of such an atmospheric argon plasma brush provides many unique advantages in practical applications including battery-powered operation and use in large-scale applications. Several polymer film samples were tested for surface treatment with the newly developed device, and successful changes of the wettability property from hydrophobic to hydrophilic were achieved within a few seconds.     

金刚石砂轮金属结合剂的气中单脉冲电火花放电去除机理

针对金属结合剂金刚石砂轮修锐困难的问题,提出采用气中电火花接触放电修锐的方法。为有效地实现微细金刚石砂轮的修锐,建立单脉冲电火花放电去除加工的试验系统,研究金属结合剂的气中和液中电火花放电去除机理。在试验研究中,主要分析无负荷电压和放电极性对脉冲放电电流、脉冲放电间隙、脉冲放电去除量、电极磨耗比等的影响。结果表明,正极性不易发生短路现象,而且气中的脉冲放电间隙小于液中的 ,适应于微细金刚石砂轮的修锐。此外,在气中放电中存在由绝缘破坏引起的火花放电向附有电弧柱的电弧放电转变的临界无负荷电压,且电火花放电的去除量可以明显小于电弧放电的去除量,但是当无负荷电压小于某一定值时电极消耗比会快速增加。修锐的试验结果显示,利用气中单脉冲电火花放电去除加工条件可以实现金属结合剂微细金刚石砂轮的修锐,产生较好的砂轮出刃形貌,改善磨削表面质量。     

A compact repetitive high-voltage nanosecond pulse generator for the application of gas discharge

Uniform and stable discharge plasma requires very short duration pulses with fast rise times. A repetitive high-voltage nanosecond pulse generator for the application of gas discharge is presented in this paper. It is constructed with all solid-state components. Two-stage magnetic compression is used to generate a short duration pulse. Unlike in some reported studies, common commercial fast recovery diodes instead of a semiconductor opening switch (SOS) are used in our experiment that plays the role of SOS. The SOS-like effects of four different kinds of diodes are studied experimentally to optimize the output performance. It is found that the output pulse voltage is higher with a shorter reverse recovery time, and the rise time of pulse becomes faster when the falling time of reverse recovery current is shorter. The SOS-like effect of the diodes can be adjusted by changing the external circuit parameters. Through optimization the pulse generator can provide a pulsed voltage of 40 kV with a 40 ns duration, 10 ns rise time, and pulse repetition frequency of up to 5 kHz. Diffuse plasma can be formed in air at standard atmospheric pressure using the developed pulse generator. With a light weight and small packaging the pulse generator is suitable for gas discharge application.     

MEMS起爆器研究现状与发展趋势

随着微纳技术的广泛应用,以MEMS技术为支撑的新一代起爆器成为含能器件领域的研究热点。MEMS起爆器可以实现大规模高密度的集成制造,并且器件输出性能一致性较好,具有微型化、集成化、高能化的特征。MEMS起爆器按结构不同,可以分为爆炸箔结构、半导体桥结构以及多孔硅结构三大类。爆炸箔起爆器主要采用电爆炸原理,结构简单,安全性能较高。半导体桥起爆器起爆电压低,应用领域广泛,可通过增加含能材料来提高器件的能量输出。多孔硅起爆器反应活性高,与由碳氢氮氧组成的传统含能药剂相比,多孔硅含能材料的环境友好性更好。通过分析与对比MEMS起爆器的结构组成、起爆方式、制作工艺以及输出能量等方面,指出MEMS起爆器结构微型化、输出高能化、起爆可控化的特征,并提出能够兼顾高能性与安全性的MEMS起爆系统为未来重要的发展方向。     

A synchronized emissive probe for time-resolved plasma potential measurements of pulsed discharges

A pulsed emissive probe technique is presented for measuring the plasma potential of pulsed plasma discharges. The technique provides time-resolved data and features minimal disturbance of the plasma achieved by alternating probe heating with the generation of plasma. Time resolution of about 20 ns is demonstrated for high power impulse magnetron sputtering (HIPIMS) plasma of niobium in argon. Spatial resolution of about 1 mm is achieved by using a miniature tungsten filament mounted on a precision translational stage. Repeated measurements for the same discharge conditions show that the standard deviation of the measurements is about 1-2 V, corresponding to 4%-8% of the maximum plasma potential relative to ground. The principle is demonstrated for measurements at a distance of 30 mm from the target, for different radial positions, at an argon pressure of 0.3 Pa, a cathode voltage of -420 V, and a discharge current of about 60 A in the steady-state phase of the HIPIMS pulse.     

半导体硅电极多通道放电机理研究

为了实现电火花加工同一时刻形成多个放电通道蚀除工件,克服现有放电加工理论中同一时刻仅有一个放电通道蚀除工件的限制,提出了采用半导体材料作为电极进行放电加工的新方法。首先,通过试验证明以半导体硅为电极加工金属可以形成多通道放电;其次,建立了半导体电极单通道放电等效电路模型,发现半导体电极在放电加工时不是一个等势体,并进行了电势差分布试验,验证了多通道放电形成的原因是远离放电点处的电势较高,可以同时形成击穿产生放电;最后,进行了半导体硅电极单脉冲放电试验及成型加工试验。试验结果显示,半导体硅电极通过1次脉冲放电同时形成多个放电通道,有效地分散放电能量,相较于金属电极,每个放电坑的直径和深度都显著减小。在相同放电参数下,对比钢电极,用硅电极进行电火花加工的表面粗糙度值下降71.7%。     

NON-THERMAL PLASMA AT ATMOSPHERIC PRESSURE: SYSTEM DESIGN AND DEVELOPMENT

The low-current non-thermal atmospheric plasma source is a useful cost-effective tool for many applications. One of the major applications of this source is to reform hydrocarbons to produce hydrogen. Here, the focus is on the design and development of a system for this process. The system described uses much lower current compared to the other thermal plasma systems and operates at atmospheric pressure eliminating the need for an expensive vacuum system. The system consists of a plasmatron, a fuel injection system for both liquid and gaseous forms, a window for inserting diagnostics systems, and a system to collect output signals from plasma. The non-thermal plasma was produced at high pressure with an AC high-frequency power supply. A three electrode system (copper, stainless steel 314, and nickel) were used with four different configurations. Initial discharge characteristics have been measured for all electrode configurations. The breakdown properties of the system with the electrode configurations and corresponding ionization coefficient (α) have been estimated. A cylindrical Langmuir probe was used to measure and estimate relevant plasma parameters.     

Study of unidirectional conductivity on the electrical discharge machining of semiconductor crystals

This paper investigates the unidirectional conductivity of semiconductor crystals machined by electrical discharge machining (EDM) by analyzing the properties of current–voltage (I–V) curves of the equivalent circuit. The simplified equivalent circuit of a semiconductor EDM consists of reverse-biased diodes and linear resistance. The I–V curve has three typical parameters, namely, conduction angle, breakdown angle, and breakdown point. The values of the conduction angle and the breakdown point are determined by the contact area of the reverse-biased diode, and the breakdown angle is determined by the value of linear resistance. Two diodes exist in the model with two metal electric feeders. To increase the current in this model, the diode with larger contact area should be reverse-biased. If the work piece is connected to anode in semiconductor EDM, the diode in the conduction side is reverse-biased and the avalanche voltage is only 42 V. If the work piece is connected to the cathode in semiconductor EDM, then the arc plasma, which is a termination with a small area, becomes reverse-biased. The temperature in the arc plasma side is high, causing the breakdown voltage to be much higher than the theoretical calculation value 88.5 V. As a result, when the work piece is connected to the cathode, spark production is difficult. Holes are bored on the P-type semiconductor crystals by positive and negative polarity, which could prove that machining with positive polarity is suitable for P-type semiconductor crystals during EDM. When the no-load voltage is set to 150 V, the penetration speed by positive polarity can reach 533 μm/min.