Deposition of SiO_x on Metal Surface with a DBD Plasma Gun at Atmospheric Pressure for Corrosion Prevention

In this study, SiOx films were deposited by a dielectric barrier discharge （DBD） plasma gun at an atmospheric pressure. The relationship of the film structures with plasma powers was investigated by Fourier transform infrared spectroscopy （FTIR）, and scanning electron microscope （SEM）. It was shown that an uniform and cross-linking structure film was formed by the DBD gun. As an application, the SiOx films were deposited on a carbon steel surface for the anti-corrosion purpose. The experiment was carried out in a 0.1 M NaCl solution. It was found that a very good anti-corrosive property was obtained, i.e., the corrosion rate was decreased c.a. 15 times in 5% NaCl solution compared to the non-SiOx coated steel, as detected by the potentiodynamic polarization measurement.

Plasma Density Measurements in Cable Gun Experiments with a Sensitive He-Ne Interferometer

A time-resolved sensitive He-Ne laser interferometer without complicated active stabilization was built up and applied to low-density plasma measurements. A precision of about 0.2° in phase measurements was achieved with a minimum line-integrated plasma density as low as 8.3× 10^13 cm^-2. With this interferometer, the characteristics of the plasma generated by a cable plasma gun was investigated systematically. The reproducibility, spatial and temporal distributions and the averaged injection velocity of the plasma are presented. In addition, the interaction of the plasma flow with a conductor was studied by placing a metal plate in the downstream of the cable gun.

Characterization of Cable Gun Plasma with a Charge Collector Array

The density, drift velocity and reproducibility of the plasma produced by a cable plasma gun array have been measured with a charge collector array. The plasma is used to prefill a coaxial plasma-opening switch with a conducting time approaching 0.4 μs. The reproducibility of the plasma source in subsequent shots is better than 5%. Near the gun nozzle and the opposite electrode, the plasma density amounts to 1015cm-3, which is 2 times to 3 times that in the gap between the two coaxial electrodes. A plasma drift velocity of about 2.4 cm/μs is observed from the time of flight of the charged particles. Both plasma density and drift velocity increase almost linearly with the rise in charge voltage.

The Use of an Electron Microchannel as a Self-Extracting and Focusing Plasma Cathode Electron Gun

A new and simple type of electron gun is presented.Unlike conventional electron guns,which require a heated filament or extractor,accelerator and focusing electrodes,this gun uses the collimated electron microchannels of an inertial electrostatic confinement（IEC） discharge to achieve the same outcome.A cylindrical cathode is placed coaxially within a cylindrical anode to create the discharge.Collimated beams of electrons and fast neutrals emerge along the axis of the cylindrical cathode.This geometry isolates one of the microchannels that emerge in a negatively biased IEC grid.The internal operating pressure range of the gun is 35-190 m Torr.A small aperture separates the gun from the main vacuum chamber in order to achieve a pressure differential.The chamber was operated at pressures of 4-12 m Torr.The measured current produced by the gun was 0.1-3 m A（0.2-14 m A corrected measurement） for discharge currents of 1-45 m A and discharge voltages of 0.5-12 k V.The collimated electron beam emerges from the aperture into the vacuum chamber.The performance of the gun is unaffected by the pressure differential between the vacuum chamber and the gun.This allows the aperture to be removed and the chamber pressure to be equal to the gun pressure if required.

Comparative analysis of the effects of gunpowder and plasma ignition in closed vessel tests

This paper presents the results of a comparative investigation into the effects of the ignition method on the ballistic properties of a single-base gun propellant,as determined via closed vessel tests.Conventional gunpowder ignition and plasma jet ignition methods were used,and differences in the ignition time were analysed.The influence of the ignition method on the dynamic vivacity is discussed.It is shown that this influence is significant in the first phase of the combustion process,and with respect to the low values of the loading density.In the second phase of the combustion process,and for large values of the loading density,the dynamic vivacity plots for the two ignition methods converge.Regarding the burning law,close values of the exponent were obtained for the two ignition methods.The dynamic vivacity plots determined for plasma ignition reveal stronger dependence on the loading density than those determined for gunpowder ignition.The conclusion is that plasma ignition is not a solution to the problems inherent to the process of determining the ballistic properties of propellants,which results in deviation of the burning process from the geometric burning law.

Study on Performance Parameters of the Plasma Source for a Short-Conduction-Time Plasma Opening Switch

Plasma source performance parameters, including plasma ejection density and velocity, greatly affect the operation of a short-conduction-time plasma opening switch （POS）. In this paper, the plasma source used in the POS of Qiangguang I generator is chosen as the study object. At first the POS working process is analyzed. The result shows that the opening performance of the POS can be improved by increasing the plasma ejection velocity and decreasing the plasma density. The influence of the cable plasma gun structure and number on the plasma ejection parameters is experimentally investigated with two charge collectors. Finally a semi-empirical model is proposed to describe the experimental phenomenon.

同轴枪放电等离子体动力学与杂质谱特性

同轴枪放电可以产生高速度、高密度及高能量密度的等离子体射流,在等离子体空间推进、天体物理和高温核聚变等研究领域具有广泛的应用.基于同轴枪的实际应用,等离子体速度、密度、纯净度是评估等离子体特性的重要参量.本文通过对等离子体光电流信号和发射光谱的测量及放电图像的拍摄,研究了不同放电电流和气压对同轴枪放电等离子体的动力学特性、电子密度与杂质发射光谱的影响.实验结果表明:气压为10 Pa,放电电流为30—70 k A时,等离子体在枪内的加速时间随电流的增大而缩短,等离子体中阳极和阴极杂质光谱均随电流的增大而增强;放电电流为40 k A,气压为10—70 Pa时,等离子体加速时间随气压的增大而增长,等离子体中阴极杂质光谱强度随气压的增加不断降低,而阳极杂质光谱强度却是逐渐增加的,不过其增长速率逐渐减小.分析认为,不同放电电流和气压决定了等离子体获能、加速特性及电子密度,协同影响金属杂质特性.同轴枪喷口处发生等离子体箍缩效应与高密度电弧在枪内加速时间是影响阳极烧蚀的重要因素,阴极材料的杂质是离子轰击溅射产生的,主要依赖于离子携带的能量.

危险废物熔融炉辅助喷枪水力学模型试验研究及应用

以广东省某10000 t/a固体废物处置系统等离子体熔融炉为例,通过搭建水力学模型试验台,对危险废物等离子体熔融炉进行辅助喷枪水力学模型试验研究及工业应用。结果表明:随着喷枪负荷的增加,穿透深度、飞溅高度、振幅、物料排出比例逐渐增大;随着喷枪布置高度的增加,穿透深度、飞溅高度、振幅、物料排出比例逐渐减小;与错列布置相比,对称布置方案的穿透深度、飞溅高度、振幅、物料排出比例更小。最终确定原型炉体的辅助喷枪设计方案为喷枪布置高度250 mm、对称布置。根据此方案的现场改造取得了预期效果,等离子体炬电耗降低28.6%,考虑氧气制备后系统电耗降低13.2%,小时运行费用降低9.8%。

等离子喷涂枪冷却水流场数值模拟

基于计算流体力学技术,建立等离子喷涂枪冷却水流场分析模型,采用求解压力耦合方程的半隐算法(SIMPLE)对其进行数值模拟.结果表明,流场内存在着局部回流和紊流,在冷却水道前端的拐弯处易形成死水区.为此,对枪体冷却水道结构进行了改进,改进后的结构可以有效地防止死水区的产生,提高了等离子喷涂枪的使用寿命.

等离子体源参数对长导通等离子体断路开关性能的影响

研制了可工作在长导通时间(约1μs)的等离子体断路开关,实验研究了等离子体源参数,包括等离子体枪与主回路之间的触发延时、等离子体枪的工作电压以及等离子体枪的数目对开关性能的影响规律。研究结果表明,开关导通时间和开关电压随触发延时、枪工作电压和数目的增加而增加,但当开关导通时间接近主回路电流四分之一周期时,开关电压呈下降趋势。当Marx发生器工作电压为120kV且采用4个等离子体枪时,实验获得的最大电压倍增系数约为1.8。

等离子喷涂设备的现状与进展

简要介绍了等离子喷涂设备的现状和发展概况，分析了等离子喷涂电源和等离子喷枪的研究进展，表明等离子喷涂设备正向大功率小型化和等离子喷枪的高效大功率化发展，逆变化是等离子喷涂电源的发展方向。

大气压聚合SiOx薄膜用于新型印刷板材的研究

以六甲基二硅氧烷(HMDSO)为单体,采用DBD等离子体枪在大气环境下进行聚合物合成,对2种不同进样方式的放电特性、聚合效果作了比较,发现2种进样方式的放电特性相同,唯一不同在于等离子体区下游进样放电等离子体炬长在低流量时先增大后减小,而等离子体区直接进样方式放电炬长直接达到起弧最大值。FTIR显示单体不同的输入方式对聚合膜结构影响不大,但对聚合膜的沉积速度有明显的影响,单体输入到等离子体区下游成膜速度明显快于单体直接进入等离子体区。扫描电子显微镜(SEM)给出了聚合膜的表面形态,表面能测试显示其接触角可达110度,推墨实验表明等离子体下游区进样聚合膜斥墨性好,可做无水胶印板材。

DBD等离子体枪聚合SiOx薄膜用于金属表面防腐性能研究

用高频介质阻挡放电(DBD)等离子体枪,以六甲基二硅氧烷为单体,在大气下于铸铁表面聚合S iOx薄膜。采用红外光谱(FTIR)分析了等离子体功率对聚合膜的结构和沉积速度等影响、SEM对试样表面进行观察。实验发现铸铁表面沉积S iOx薄膜呈现致密纳米棒状交联结构,并随着厚度的增加粒子间出现团聚现象。在0.5%NaC l溶液中的腐蚀实验表明,S iOx薄膜能显著的提高铸铁的防腐性能,而通过在5%NaC l溶液中进行的动电位极化特性曲线计算得到,铸铁的腐蚀速率为4.72E-3mm/a,约为纯铸铁的1/15。

内送粉超声速等离子喷涂流场特性分析

应用流体控制方程、传热传质方程、粒子输运方程、Maxwell电磁场方程建立多场耦合数学模型，通过数值计算方法研究超声速等离子喷枪内外等离子体流动特性。所采用的内送粉三维模型包含阴、阳电极固体以及阳极边界层区域，考虑了等离子气体的电离与复合反应，以及局域热平衡效应，得到了超声速等离子喷涂在纯氩和氩氢混合气氛中的气流温度场、速度场分布以及电弧电压分布。结果表明：在加入氢之后，喷枪内等离子体温度提高了30%，速度提高了67%；喷枪外气流速度和温度在距喷嘴出口0~50mm间梯度变化大于喷涂距离50~100mm，且径向速度和温度梯度变化随着喷涂距离增大越来越小。计算得到的电弧电压与测量值相差4.4%，说明了考虑阳极边界层后计算模型的合理性。

HA 生物活性陶瓷涂层的爆炸喷涂与等离子喷涂

采用爆炸喷涂与等离子喷涂两种工艺制备ＨＡ生物活性陶瓷涂层，并对两种层进行对比研究．采有ＸＲＤ、ＳＥＭ等方法分析涂层的物相组成和显微结构．发现爆炸喷涂的涂层结构致密、结晶程度较高；等离子喷涂的涂层则具有较高的孔隙率，涂层非晶化现象明显．经适当温度热处理，两种涂层的结晶程度均可明显提高．

等离子枪体流场形态仿真分析

在确定合理的等离子枪体冷却水道模型的基础上,运用有限元分析软件对等离子枪体内冷却水流场进行了仿真分析.在施加合理的边界条件,设定合理的求解策略后,对问题进行了求解,并分析了求解结结果.说明了该软件在对等离子枪体流场形态仿真分析中的有效性.

等离子体喷枪中的射流脉动控制

电弧等离子体喷枪中的射流脉动是影响等离子体喷涂质量的一个非常重要的因素 ,射流脉动很大程度上是由于等离子体喷枪内电弧分流引起的。分析了电弧分流的机理及其对射流脉动的影响。在此基础上 ,设计了一种直流等离子体喷枪 ,采用在阳极和阴极中间设置隔离段的方法来限制电弧的大尺度分流。为了研究电弧分流对射流脉动的影响以及检验新喷枪对射流脉动的抑制作用 ,而建立了专门的试验装置并进行了相关的试验。试验结果表明 ,电弧分流和射流脉动的频谱特性是一致的 ,在使用新等离子体喷枪时 。

等离子体加速器动力学理论探索

等离子体驱动微小碎片加速器是利用大容量脉冲电容器组对等离子体同轴枪放电产生高温、高密度、高速等离子体,再用这些等离子体加速微粒(10～1000μm)至超高速(1～15km/s)以模拟mm级以下空间碎片撞击效应的地面试验装置。为了提高微粒速度,需要增加等离子体的动量,而等离子体的动量与工作气体的性质及定向速度密切相关。文章用数值模拟及解析计算等理论方法来探索等离子体轴向速度、密度和温度与放电条件、加速电极参数和工作气体之间的关系。通过研究等离子体束与微粒间相互作用的动力学行为,寻求优化试验装置效率的有效途径。

等离子枪体喷嘴结构和尺寸对电弧能量的影响

为了研究等离子枪体喷嘴结构和尺寸对电弧能量特征的影响,建立了等离子电弧的数学模型,并采用计算流体动力学(CFD)软件求解了等离子流体质量、动量及能量守恒方程和麦克斯韦方程组.通过对等离子枪体的电弧模型进行求解,得到了等离子电弧沿轴向的温度和速度分布.在此基础上研究了喷嘴通道长度、喷嘴直径和喷嘴压缩角对等离子枪体电弧的影响.结果表明:喷嘴通道长度的增加对等离子电弧的压缩效果影响较小;喷嘴孔径的减小对电弧的压缩效果则很明显.当通道比为1～1.2时,电弧温度和流动速度比较稳定,对阳极表面压力较小,对焊接成形有利.

改进型等离子喷枪的粒子飞行特性

对非转移型等离子喷枪改进设计,并用SprayWatch-2i喷涂粒子速度温度测试仪对喷涂粒子速度进行测试,比较了喷枪改进前后和不同喷嘴对ZrO2粒子速度和温度的影响。研究表明,改进型喷枪使粒子速度明显提高,超过音速;减小喷嘴孔径有助于提高粒子速度;随着粒子速度的提高,粒子加热时间缩短,粒子温度有所降低。