真空罐穿舱法兰介质微放电的实验研究

介质微放电已经成为制约航天器有效载荷地面研制和在轨可靠运行的重要因素.本文对航天器环境模拟试验中真空罐穿舱法兰介质表面单边微放电进行了实验研究,在周期性脉冲信号激励下,观察到调零信号间歇性局部跳变的现象.采用三维粒子模拟工具对微放电从起始到饱和的演化过程进行了数值模拟,结合模拟结果给出了实验现象的物理解释及若干讨论.研...     

介质阻挡放电中微放电周期特性的光学测量

采用特殊设计的双水电极介质阻挡放电装置,利用光学方法原位、无干扰地测量了大气压空气介质阻挡放电中微放电的单脉冲特性和周期特性,实验上首次发现在介质阻挡放电斑图模式中,微放电在驱动电压的正负半周的放电时刻并不是固定的,相邻两次放电的时间间隔是长短交替的。根据壁电荷对微放电通道相邻两次放电的不同作用,分析了相邻两次放电时刻的联系,很好地解释了相应的实验现象。     

介质阻挡放电中微放电的映射方程

利用双水电极介质阻挡放电装置，采用光学方法测量了大气压空气和氩气中介质阻挡放电的微放电时间特性.实验发现微放电通道相邻两次放电时间间隔是长短交替的.根据壁电荷对相邻两次微放电的不同影响，建立了介质阻挡放电时间序列的映射方程.不同放电参量取值情况下的计算结果表明，介质阻挡放电中，壁电荷电场的衰减时间常数远大于100μs量级.由方程所得的结果，解释了相邻两次放电时间间隔长短交替的实验现象，确定了壁电荷衰减时间常数的范围. 关键词： 介质阻挡放电 时间特性 壁电荷 映射方程     

光学方法研究介质阻挡放电中的微放电特性

首先用真空光电倍增管测量了斑图模式大气压介质阻挡放电的总光信号 ,并通过在电路中串联小电阻的方法测量了放电的电流信号。结果发现 ,两种方法所测得的信号在幅度和位置上存在严格的一致性 ,说明可以利用光学方法测量介质阻挡放电的电流信号。采用光学方法测量了介质阻挡放电中的微放电通道的时间特性。本工作所得到的结果对于介质阻挡放电的时空动力学研究具有重要意义 ,同时对气体放电研究具有一定的参考价值。     

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     

大气压介质阻挡辉光放电中放电电流的测量与分析

介质阻挡放电产生的低温等离子体具有广泛的应用前景而成为研究热点。文章利用平行平板介质阻挡放电装置,在流动的氦气中实现了大气压均匀辉光放电,得到了大气压下的均匀等离子体。利用电学方法将放电电流从总电流中分离出来,从而得到了辉光放电的放电电流。通过分析放电电流、外加电压、气隙上电压以及壁电荷电量之间的相互关系,可以研究气体放电过程中壁电荷积累的微观动力学行为。实验结果表明壁电荷主要是在放电电流脉冲持续期间积累的,但电流脉冲结束后,由于气隙电压没有改变极性,壁电荷还会逐渐积累,气隙电压改变极性后,壁电荷量随时间减小。这些结果对壁电荷在介质阻挡辉光放电中作用的深入研究和大气压介质阻挡辉光放电的工业应用具有重要意义。     

空气介质阻挡放电单个微放电通道发光强度及振动激发温度的空间分布

通过清洗放电方法,在平行平板介质阻挡空气放电中得到了单个稳定的微放电通道（又称放电丝）.测量了从瞬时阳极到瞬时阴极单个放电丝的发光强度及振动激发温度的空间分布.研究表明：在外加电压的每半周中放电丝发光呈现杯型分布,杯底位于瞬时阴极处;振动温度在两平行板间隙的中心处最高而在瞬时阳极处最低. 关键词： 介质阻挡放电 微放电通道 振动温度     

电荷电压法测量DBD等离子体的放电参量

在DBD应用研究中，使用电荷电压法能够测量许多重要参量，如放电功率、放电间隙等效电容、电介质层等效电容、着火电压、放电间隙等效电压及放电间隙电场强度等．同时根据电荷电压图形随工作条件及状态变化的情况还可以诊断DBD等离子体的工作稳定性．文章对相关原理、模拟实验结果及实际应用效果进行了介绍．     

电解质浓度对胶体粒子表面有效电荷的影响

胶体粒子的表面有效电荷是决定胶体性质的重要物理量,但溶液环境(如电解质溶液浓度)是否影响其数值至今尚无统一认识,近年来的一些研究工作给出了存在争议的不同结果和假设.在直接实验测量方面,由于电解质离子和胶体表面吸附离子的置换,粒子表面基团的不完全电离和胶体粒子对离子吸附的共同作用,使得对这类粒子在不同溶液环境下的表面有效...     

Estimation of surface charges on dielectric materials for high power rf windows

The surface discharges observed at rf windows and vacuum circuit breakers (VCBs) are one of the difficulties faced when developing high-power rf windows or compact VCBs. The surface discharge is considered to take place due to the release of the surface charges. Despite the importance of the surface charging/discharging, these phenomena have not been well evaluated. In this paper, the surface charges are estimated using the multipulse method, where electron beam irradiates a sample up to the saturation condition of surface charges. The amount of surface charges on alumina and TiN coated alumina are compared and the charging mechanism is discussed.     

Electric fields in dielectric structures with nonuniformly distributed surface charges

The distribution of the potential and intensity of the electric field in dielectric structures with a nonuniform surface charge is analyzed. Computational formulas are proposed and computational results are presented. Zh. Tekh. Fiz. 69, 138–140 (August 1999)     

Numerical computer calculation of distribution of similar point charges at the dielectric surface

Results of numerical calculation of the distribution of similar point charges over a uniformly charged dielectric plane are presented for different surface charge densities and surface temperatures. It is shown that, in the case of the surface charge density ranging from 2 × 10⁻⁶ to 7 × 10⁻⁵ C/m² and temperatures ranging from 300 to 800 K, the Lindemann criterion is fulfilled for the average deviation of the point charge from the equilibrium position, and the collection of point charges at the dielectric surface can be regarded as a 2D Coulomb crystal.     

Observation of space charges in the photorefractive region and surface electric breakdown in LiNbO3-Fe

The space chages formed in the process of photorefraction in LiNbO₃ crystals is visualised by charged powder techniques. The results confirmed the existence of space charge carriers at the periphery of the illuminated region with negative charge carriers in the +z periphery and positive in the –z. The observed patterns on the surface of LiNbO₃-Fe (0.05%) crystal illuminated with higher light intensities presented discharge-like features, namely traces of discharge in the medium at the crystal surface. The correlation between the kinetics curves of birefringence changen(t) and the revealed surface patterns indicated that electric breakdown of the medium at the surfaces was responsible for the periodic reduction ofn(t).     

Synchrotron radiation of charges distributed in space

We investigate characteristics of spontaneous radiation of a uniformly charged rod orthogonal to a given plane and moving such that is projection on this plane moves uniformly on a circle. It is shown that the power of radiation of such charged structure is smaller than the power of radiation of point charge of the same value and moving on the same circle. With increasing energy, the power of radiation increases slower than the power of synchrotron radiation.Institute of High Current Electrotechniques, Siberian Branch, Russian Academy of Sciences. Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 23–25, January, 1993.     

Electrostatic potential of point charges inside dielectric oblate spheroids

As a sequel to a previous paper on electrostatic potential of point charges inside dielectric prolate spheroids [1], this note further presents the exact solution to the electrostatic problem of finding the electric potential of point charges inside a dielectric oblate spheroid that is embedded in a dissimilar dielectric medium. Numerical experiments have demonstrated the convergence of the proposed series solutions.     

Electrostatic potential of point charges inside dielectric prolate spheroids

The exact solution to an electrostatic problem of finding the electric potential of point charges inside a dielectric prolate spheroid is discussed in this note by using the classical electrostatic theory, where the prolate spheroid is embedded in a dissimilar dielectric medium. Such a problem may find its application in hybrid solvent biomolecular simulations, in which biomolecules and a part of solvent molecules within a dielectric cavity are explicitly modeled while a surrounding dielectric continuum is used to model bulk effects of the solvent beyond the cavity. Numerical experiments have demonstrated the convergence of the proposed series solutions.     

声脉冲法空间电荷测量系统的研究

气体中空间电荷的分布与电晕放电的机理紧密相关, 获取电晕放电过程中空间电荷分布对深入研究电晕放电起始、自持过程有着重要作用, 但是如何准确获得电晕放电过程中的空间电荷分布一直是国际上尚未解决的难题. 本文基于声脉冲法提出一种电场信号解耦算法, 推导了空间电荷在声场中被调制产生的电场信号与声脉冲信号和空间电荷密度之间的数值关系, 讨论了不同测量情况下声发射系统的设计要求; 搭建了一套可用于实时测量针板电极电晕放电空间电荷分布的非接触式测量系统, 该系统主要包括声脉冲发生模块、空间电荷模块及电场信号解耦算法模块. 运用该系统实现了声脉冲激发作用下电场信号的测量, 通过提出的电场信号解耦算法得到了空间电荷密度, 对其测量结果与电晕电流法测量结果进行比较, 验证了电场信号解耦算法的有效性. 该算法可以应用于空间电荷一维、二维和三维测量系统中.     

Deflection of sputtered ions by surface charges

The trajectories of ions sputtered from an insulating surface carrying a surface charge have been computed. The results show that yields measured in particular directions can be in serious error as the trajectories of low energy sputtered ions depend critically on surface charge and point of origin of the ion. The distorted yield curves for 1.2 eV ions and 10 eV ions leaving a surface with a ten volt surface potential are calculated.     

导体球壳上感应电荷及空间电场的分布(2)

本文利用镜象法讨论了在不接地导体球壳附近有点电荷时，空间的电场分布和球壳表面上感应电荷的分布。