电极移动速度效应的空气动力学分析

基于空气动力学原理解释了电极向靶运动过程中放电间隙形成局部低真空的机理.结合小间隙放电的双过程模型, 初步阐释了气体压强变化对放电间隙内部相关电参量的影响机理, 进而分析电极速度对放电参数的影响.基于我们团队自主研制的电极移动速度效应检测仪,进行反复实验, 对大量的试验数据进行仿真分析, 探索小间隙静电放电过程中放电参数对电极移动速度的依赖性.结果表明:电极移动速度与放电电流峰值、放电电流脉冲上升速度, 具有高度的正相关性; 与放电电流脉冲下降速度具有高度的负相关性.研究结果对于推进非接触静电放电测试标准的提出具有一定的参考意义.     

BP神经网络预测电极速度影响放电参数分析

文中结合小间隙放电的双过程模型,探讨电极移动引起放电场强和压强的变化对放电间隙内部相关因子的影响。文中同时利用BP神经网络预测分析电极移动速度对放电参数的影响。基于静电放电电极移动速度效应检测仪,不断改变电极移动速度,反复多次进行放电实验并统计试验数据。利用BP神经网络对已测实验数据进行训练、学习,从而预测不同速度与压强下对应的电流上升时间和峰值电流大小。实验结果表明,放电电流的上升时间与电极移动速度不存在相关性。根据新方法预测出的不同速度下的峰值电流和实际大小相比准确率更高。研究结果对探寻非接触式静电放电的规律和制定静电放电标准有一定的参考价值。     

非接触静电放电测试低重复特性分析研究

基于自主研发的新型测试系统,对小间隙静电放电(Electrostatic Discharge,ESD)中电极移动速度和气体压强引起放电参数的低重复离散特性进行探讨.新型测试系统采用机电一体化设计,解决了带电体与受电体高速相向运动与避免强烈撞击损坏仪器的难题,并实现对多种影响因素的有效测量.用新型测试系统测量了气体压强变化和向放电靶移动电极速度等放电参数.静电放电模拟器移动距离控制在(10～40 cm)的范围.电极移动速度变化(v)为14 cm/s,则放电电流峰值改变(J)达到0.5A,空气压强变化对放电电流最高峰值的影响十分明显,压强变化(p)为0.06个大气压时,则峰值电流变化(D为0.5A,证明了电极移动速度和空气压强对放电参数产生的影响;对放电参数受电极移动速度和气体压强变化而出现显著差异的可能机制给出了初步分析.     

人体静电放电参数对带电电压的依赖关系研究

在带电电压为200～3000V的范围内测量了带电人体放电电流和上升时间,计算了其他放电参数;研究了放电参数与电压和电板速度的相关性.将RampeWeizel定理用于空气中带电人体的小间隙静电放电模型.观察发现在电压为800V时放电参数在电极运动速度影响下出现临界值.当电压高于1000V,或低于600V时,电极移动速度对放电参数的影响出现降低的趋势.     

在小间隙放电中用Bernoulli定理分析电极移动速度效应

小间隙静电放电中电极移动速度对放电参数影响的内部因素,是受到很多研究者关心的问题.通过对实验数据的系统分析,应用流体力学中Bernoulli定律,对放电参数电极速度效应的内部原因,提出了较好的理论解释.电极的快速运动速度造成了放电间隙气体压强的下降,从而加速了载流子从电极到靶的运动过程,进而明显改变了放电参数的数值.初步的数值计算表明,表面过程因电极快速移动得到了加强.这对于电极移动速度效应进一步的研究,给出了一种较为明确的方向.     

小间隙静电放电中的电极移动速度效应研究

分析已发表的静电放电研究文献,设计了电极移动速度效应测试仪。该新型测试系统通过独特的机电一体化设计,为带电电极既要高速向靶运动放电以研究快速移动速度对放电结果的影响,又要避免二者可能产生强烈碰撞损坏仪器,就静电放电领域长期困扰研究者的难题提供了解决方案。对电极移动速度效应用模型方法和流体动力学理论进行了分析推导,将Townsend放电理论结合小间隙放电模型给出气体压强影响放电电流结果的算法。基于电极移动速度效应测试仪的功能和数据,对所提出的理论分析结果和算法进行了初步验证和讨论。     

静电放电参数对电极速度的相关性与机理分析

同步测量了带电人体手握金属小棒电极放电电流的参数和电极运动速度.金属小棒电极与靶电极相撞时的速度对放电电流参数(放电电流峰值、放电电流时间变化率的峰值、火花放电的弧长)的影响,用统计软件SPSS进行了考察,获得了在不同人体电压情况下小棒电极运动速度与放电参数的相关系数.结果表明:充电电压为0.3kV时,放电参数与电极运动速度无关.充电电压为0.5kV及其以上电压时,电极运动速度与放电电流峰值、电流最大上升斜率有极强的正相关性;与放电火花弧长有极强的负相关性.电极向靶的快速接近改变放电间隙的空气压强,改变间隙两端的电场强度,从而引起放电参数的显著变化.     

基于Attention-LSTM-XGBoost的电极移动速度影响放电参数预测分析

基于具有Attention机制的长短期记忆(attention long short-term memory,Attention-LSTM)神经网络模型,设计了一种由Attention-LSTM神经网络与极端的梯度增强(extreme gradient boosting,XGBoost)法共同组成的变权组合模型,用以分析预测静电放电过程中电极移动速度对放电参数造成的影响。该组合模型充分利用静电放电参数的时序特性,并采用Attention机制突出对放电参数预测起到关键作用的输入特征。首先基于由新型电极移动速度效应测试仪的实验结果提供的原始实验数据,采用分箱法对其进行预处理得到新的实验数据;然后将得到的新实验数据集作为两种模型的输入数据,分开训练Attention-LSTM模型和XGBoost模型,求解出各自模型的预测结果及误差;最后利用误差倒数法,重新计算出两种模型预测结果的占比权重,并根据计算的权重求解出最终预测结果。预测结果表明：与Attention-LSTM神经网络模型、XGBoost模型、Attention-LSTMXGBoost定权组合模型相比,本文构建的Attention-L...     

空气ESD辐射电磁场和放电间隙区分布研究

在固定放电空气间隙条件,利用电流靶和半圆环天线对空气静电放电(ESD)的辐射电磁场进行了探测和记录,根据空气ESD辐射电磁场的特征研究了空气ESD的放电特性和放电间隙区分布规律。提出了空气ESD存在"增长间隙区"、"跌落间隙区"、"平坦间隙区"和"零放电间隙区"4个放电间隙区,放电间隙区的分布主要与放电电压的大小相关,且在高电压时各放电间隙区分布更明显;一定电极接近速度下的空气ESD与一定放电间隙区的空气ESD相对应。     

电晕风干燥实验的研究

在自制的电晕风干燥装置上,对水进行了干燥实验.通过改变放电间隙、针状电极的数目和放电电压,对影响电晕风干燥速率的因素做了初步的研究.实验结果表明:放电间隙越小,针状电极数目越多,输出电压越高,干燥速度越快.在此基础上,又对土豆片进行了干燥试验.     

Voltage dependence property of parameters for human body discharge in air through a small metal rod

Discharge parameters are measured and calculated in electrostatic discharge （ESD） from charged human body through a small moving handheld metal rod. Correlation study has been performed on discharge parameters with charge voltage as well as approach speed. At charge voltage 800 V, difference of discharge parameters caused by fast and slow approach speed of electrode is found to reach extreme values. To explore the reason for this special case, an analysis with a short-gap ESD model is carried out.     

A measurement of very fast transition durations due to gapdischarge in air using distributed constant line system

Very fast transition durations (rising time in positive polarity and falling time in negative polarity) due to starting of gap discharge were investigated in time domain. The gap space was set very small for voltages below 1500 V as a simulation of the charged device model (CDM) electrostatic discharge (ESD) and the gap discharge of switch devices. The measurement system consists of a distributed constant line system with a tapered coaxial electrode, which has a matched impedance for the characteristic impedance of the distributed constant line system. The insertion loss of the tapered coaxial electrode was within -3 dB in the frequency range below 4.5 GHz. The atmosphere around the electrode is ordinary air. This experimental system enables one to measure the high-speed transients of about 100 ps due to gap discharge in time domain. As a consequence of the experiment, the relationship between the discharge voltage and transition duration was confirmed. The voltage rise time was slowed down gradually in positive polarity, while the voltage fall time was slowed down remarkably in negative polarity for the 0.1-mm needle     

Correlation investigation between contact approach speed of handheld metal rod and discharge parameters from charged human body

Characteristic measurement of contact discharge currents are made through a hand-held metal rod from charged human body. Correlation coefficients are obtained, through Statistic Package for Social Science （SPSS）, for various charge voltages, which is based on the effect test of electrode contact approach speeds on discharge current parameters of current peaks, maximum rising slope and spark lengths. Discharge parameters at charge voltage 300V are independent on approach speed. For charge voltages equal to and higher than 500V, the contact approach speed has strong positive correlation with discharge parameters of the peak current and the maximum rising slope, whereas has strong negative correlation with the spark length.     

Electrostatic linear microactuator mechanism for focusing a CCDcamera

A newly developed linear electrostatic microactuator mechanism employing a vibrating motion is described. In order to achieve a miniature charge coupled device (CCD) camera with autofocusing and zoom functions, we developed an electrostatic linear microactuator with a large movement range. In miniature CCD cameras, extremely thin electrostatic actuators are needed because the space available for the focusing mechanism is reduced. The moving part (slider) of this actuator is sandwiched between fixed electrodes (stator), is alternately attached and detached to these fixed electrodes, and actuates linearly on a macroscopic level. The fundamental feasibility of this vibrating motion mechanism was first confirmed in experiments. This actuator was then applied to the focusing mechanism of a miniature CCD camera. A microlens was fitted inside the slider and it was possible to adjust the focus by moving the slider (with microlens). The size of the prototype for the focusing mechanism is 3.6×4.6×8.0 mm, and a 2-mm movement range is achieved. The minimum driving voltage is 60 V and the maximum velocity is 1.0 min/s     

Investigations of two-stage-pseudospark switches for high-currentapplications

To avoid the lowering of the holdoff voltage due to the electrode erosion in one stage high current pseudospark switches (PSS), a two stage PSS with no axial aperture in the intermediate electrode was tested. For investigations a pulse generator was used generating peak currents up to 120 kA at a maximum voltage of 30 kV with a period length of 5 μs of a weakly damped sine wave with 90% current reversal. In comparison with a one stage PSS the breakdown characteristic was shifted to higher pressure. With a free floating intermediate electrode, the device could not be triggered, however, with additional capacities of a few nF between the three electrodes the discharge was ignited. The discharge in the second gap is triggered by the pseudospark discharge in the cathode gap, discharging the auxiliary capacities. Simultaneously, observation of both gaps with fast shutter photography showed an independent movement of the discharges in the two gaps. In the cathode gap as current increases, the discharge moves away from the center to the plane electrode surface as has been observed in the one stage PSS. However, in the anode gap the discharge moves away from the center after a contraction to the center. The two discharges are transmitted to metal vapor arc type discharges as the erosion patterns prove. With this kind of a two stage PSS holdoff voltages exceeding 35 kV would be possible. The characteristic switch data, i.e., delay and jitter, are nearly equal to a one stage PSS