关于静电屏蔽上限的讨论

将导体壳放入外电场中,导体会在表面产生感应电荷,并达到静电平衡状态,导体壳腔内的电场处处为零,这就是静电屏蔽效应.然而,如果外电场极强,或者导体内部的自由电荷太少,以至于感应电场不能完全抵消外电场,则静电屏蔽效应将失效,这就是静电屏蔽的上限问题.本文从静电屏蔽的原理出发,将导体壳简化为一对平行金属平板的模型,定量的讨论了这一问题.通过计算我们发现,由于金属内存在大量的自由电子,在非极端问题中,宏观的导体装置都远远不会遇到静电屏蔽的上限问题.     

静电平衡、静电屏蔽有极限么?

静电平衡和静电屏蔽是电磁学中的重要知识点,其关键在于导体中存在大量自由电子,在外加电场作用下形成新的电荷分布,由此产生的附加电场抵消外加场使得导体内部电场处处为零.那么如果持续增大外加电场,静电平衡和静电屏蔽是否能一直实现?静电平衡和静电屏蔽是否有极限?本文分析了静电平衡在外加电场逐渐增强下,从开始被打破的临界状态到完全被打破的极限状态的变化过程,并以铁质外壳为例分析了静电屏蔽被打破所需要的场强和电势差.     

静电技术应用专题系列介绍：第一讲 静电引起的力学现象及其应用

本文从物理的角度，阐述了粒子在静电场作用下的静力学和动力学现象．并对静电除尘、静电喷涂、静电分选以及电帘等工业应用技术进行了介绍．     

创新静电现象实验 提高物理课堂效能

近些年, 越来越多的高中物理教师在物理教学课堂上运用物理演示实验教学来为学生呈现生动的物理 现象, 使各种物理知识及原理得到直观的解释. 笔者就高中物理实验中最困难的一类实验 — — — 静电实验进行突破 性的创新设计, 用于教学实践, 做到师引导, 生思考, 师操作, 生细看. 大胆创新静电演示实验, 提高学生核心素养, 取 得了很好的教学效果     

小实验 大道理 — — —“ 静电现象”实验开发行与思

从“ 静电实验”的实验困难入手, 通过对静电实验的开发与整合, 在此基础上进行再设计, 优化教学过 程. 通过案例中呈现的小实验, 反思把握教材的3层境界、 课程资源开发的另一种角度和相应的学生观     

静电飞花激发高中生物理探究实验的兴趣

利用静电飞花激发学生进行物理探究实验的兴趣,在探究过程中以学生为中心,学生通过观察现象会发现并提出问题、依据实验操作步骤设计实验探究方案、由实验现象总结出实验结论.探究过程中教师只是起引导作用,对于探究过程中发现的新问题,引导学生通过进一步实验寻求答案.以探究实验的形式进行科学探究,培养科学思维,渗透科学态度与责任.     

自制综合创新教具突破静电教学重点

不少教师在教学电学知识时,无法让学生形象地体验到电学概念.依托创新实验教具开展的教学不仅可以起到化抽象理论为形象认知的作用,还可以充分调动学生学习积极性,激发学习兴趣.本文设计了"静电跑道"与"悬浮静电泡"课堂教具,并对教具的原理、制作、使用过程与课堂应用进行分析,从而帮助教师建构探究型课堂,进而起到通过实验现象解释内化知识要点、依托原理分析渗透物理核心素养的作用.     

静电平衡时导体上电荷的分布初探

在高中物理教材对电荷分布阐述的基础上进行扩展,用高斯定理对静电平衡状态下导体上净电荷分布进行一些分析.     

光电反馈式静电悬浮的机制研究

本文主要讨论光电反馈式静电悬浮的理论问题。研究在静电场作用下导电悬浮体的静电感应机制和绝缘悬浮体的静电极化机理,推导出悬浮体表面的感应电荷或极化电荷的计算公式,以及作用于悬浮体上的静电悬浮力的计算公式,在理论上揭示了静电力与电极电压、电极面积、悬浮间距及悬浮体电学特性等因素之间的关系。结果表明,导电悬浮体表面的感应电荷量比绝缘悬浮体表面的极化电荷量多,因此前者所受的静电悬浮力比后者大,但两者均可实现静电悬浮,这些结论与实验结果完全符合。本文工作为实现静电悬浮的光电反馈控制提供了理论依据。     

浅谈静电的危害及其应用

随着科学技术的发展,由静电所带来的负面效应及静电的应用,越来越受到人们的重视.本文简要地从静电产生的原理入手,介绍静电带来的常见危害,及其在不同领域中的应用.并展望了静电应用的发展趋势.     

Analytics of period doubling

Approximate analytic solutions for periodic orbits of the quadratic mapxrx(1–x) are developed using algebraic methods. These solutions form the basis of an exact algorithm which predicts the quantitative order of periodic points characteristic of the Feigenbaum scenario. The algorithm holds for any one dimensional unimodal map. A general procedure is developed which permits calculation of period doubling parameters for large period orbits from those of low period to any desired degree of accuracy. Explicit equations are given through second order.     

Analytics/Methods

An overview is presented of biomedical applications of stable isotopes in general, but mainly focused on the activities of the Center for Liver, Digestive and Metabolic Diseases of the University Medical Center Groningen. The aims of metabolic studies in the areas of glucose, fat, cholesterol and protein metabolism are briefly explained, as well as the principle of breath testing and the techniques to study body composition and energy expenditure. Much attention is paid to the analytical considerations based upon metabolite concentrations, sample size restrictions, the availability of stable isotope labelled substrates and dose requirements in relation to compound-specific isotope analysis. The instrumental advantages and limitations of the generally used techniques gas chromatography/reaction/isotope ratio mass spectrometry and gas chromatography/mass spectrometry are described as well as the novelties of the recently commercialised liquid chromatography/combustion/isotope ratio mass spectrometry. The present use and future perspective of infrared (IR) spectrometry for clinical and biomedical stable isotope applications are reviewed. In this respect, the analytical demands on IR spectrometry are discussed to enable replacement of isotope ratio mass spectrometry by IR spectrometry, in particular, for the purpose of compound-specific isotope ratio analysis in biological matrices.     

A Stability Analysis of an Electrostatic Precipitator Ionizer

An original study of wire oscillation in the ionizer unit of an electrostatic precipitator was made. The ionizer unit was modeled into a theoretical block diagram system, from which stability criteria were derived. Experimental measurements of the system parameters were devised. A comparison of an experimental single wire, double plate model and the theoretical system model resulted in close agreement.     

静电四极透镜中非线性传输的Lie代数分析

用Lie代数方法分析了带电粒子在静电四极透镜中的非线性传输,结果为三级近似.分析过程为:首先建立粒子在静电四极透镜中的运动的Hamilton函数,然后将Hamilton函数在平衡轨道附近展开成幂级数,最后计算粒子的非线性轨迹到三级近似.根据需要,还可以扩展到更高级近似解.     

静电分析器非线性轨迹的Lie代数分析

介绍了Lie代数的方法，用Lie代数方法分析了静电分析器对束流传输过程的非线性影响，其计算结果分析到三级近似. 首先给出了静电分析器的哈密顿函数，然后将哈密顿函数展开为齐次多项式的和，再求Lie映射，最后得到粒子轨迹各级近似解.     

人体静电放电对有机发光二极管的影响

研究了静电放电（ESD）人体模式（HBM）下的脉冲应力对有机发光二极管（OLED）的性能及寿命的影响,并讨论了相应的物理机制。对比分析了4组OLED在施加ESD放电为0,200,800,1 600 V前后的电学和光学特性,并进行了相应的寿命测试分析。研究发现,OLED器件的光谱对ESD不敏感,随着冲击电压的增大,由于静电打击对载流子的短期抑制效应,OLED的亮度出现轻微下降。在静电冲击电压为200 V和800 V时,伏安特性没有发生变化;当静电冲击电压增至1 600 V时,反向漏电有明显增加。后续的加速寿命实验表明,静电打击对器件的工作寿命没有明显的规律性影响,但是会一定程度提高非本质老化失效的概率。     

静电放电火花产生的电磁场特征分析

静电放电(ESD)产生的电磁脉冲(EMP)会对电子系统的正常工作造成严重的干扰,甚至造成系统的损伤.故提出了一种修正的ESD火花电偶极子模型,并用此模型定性地分析了ESD火花产生的电磁场的特征,得出的-些结论对进一步研究ESD的电磁防护措施提供了有益指导.     

Electrostatic deceleration of the LEAR antiprotons

A high voltage electrostatic column is proposed for an efficient deceleration of the 60 MeV/c LEAR antiprotons down to an energy where they will be trapped and cooled. The column, made of standard NEC tubes connects the LEAR beam line to an SF6 isolated terminal in which the energized (but disconnected) superconducting solenoid and associated components are placed. The charging chain ramps the terminal voltage to its final value (slightly less than 2 MV) during the few seconds preceding the LEAR beam injection and returns the voltage to a preselected low value within the following few seconds. The decelerated antiprotons have less than 10 keV energy spread and can be optimally trapped, cooled and extracted into a high quality low energy beam.     

Analysis of Three-Dimensional Motion of Relativistic Electrons in Ion-Focused Electrostatic System

Three-dimensional motion of relativistic electrons in ion-focused electrostatic system, which is the basis of investigating the ion-channel electron cyclotron maser (ICECM) or circular polarized ion-channel laser (CPICL), is analyzed through nonlinear numerical simulation. The results show that the projection of electron orbit in cross-section is, in general, a precessing ellipse with a center on the axis of the ion-channel in a cylindrical ion-focuse electrostatic system. When injection electrons satisfy a specific condition, the electrons can have a steady circular orbit. The effect of relativistic factor on electrons' motion is discussed. Using the perturbation method, the eigenfrequency of this system is derived as Equation $ \sqrt {4 - \beta _ \bot ^2 } \omega _0 $ where wo is the cyclotron frequency of the electrons. This implies that there may exist a new kind of instability in ICECM or CPICL.     

粉尘云电火花最小点火能的统计分析

基于统计分析的Logistic回归模型,应用以概率表示粉尘云最小点火能的计算方法,在容积为1.28L的Mike 3管内对不同浓度的烟酸粉尘-空气混合物进行了最小点火能测试实验,利用SPSS软件计算得到了各浓度下烟酸粉尘云点火成功概率为10%和50%时的最小点火能。结果表明,烟酸粉尘云最小点火能随浓度的增大呈现先减小后增大的趋势,最后保持在一定的能量范围内。与其他标准的计算结果相比,这种方法给出的结果更符合实际情况,也能满足不同生产环境对安全控制的需要。