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邓宏李波2015《近代电介质理论》DIELECTRIC STRENGTH AND INSULATION BREAKDOWN一、电介质击穿（Dielectric Breakdown ）UIOU bU b 为击穿电压（击穿电场E b =U b /d，d为介质厚度）导体电介质由绝缘体击穿时，当常数在低电压区满足：→⇒⇒∞→==Ubb dUdI U U dUdI击穿的分类：•本征击穿（Intrinsic Breakdown ）：电击穿；•非本征击穿：热击穿（Thermal Breakdown ）；•放电击穿（Discharge Breakdown ）•击穿是一种原子或分子聚集体的集体现象。
•“自愈现象”（Self-Healing ）：气体（包括一些液体介质），在电场的作用下被击穿，当外电场撤除后，气体介质又恢复其绝缘性能。
•固体介质的击穿是永久性的。
二、气体介质的击穿)/(2m A j )/(m V E IIIIII1E iE Sj bE 如电场很高，例如E>108V/m ，离子在电场中获得很高的能量而产生新的碰撞和电离，使N 随E 的增大指数增加，导致电流的指数增大。
1002003004001010 1010 10 10 10 1010100 HGFEV Vs与初始引发有关着火电压VDCA常见的放电形式：AC 段属于非自持放电-火花放电自持放电正常辉光放电区EF 段-辉光放电欠正常的辉光放电区CD 段-电晕放电起辉电压异常辉光放电FG 段弧光放电GH 段放电维持电压辉光放电发光区域及光强分布图当辉光放电时，在放电管内形成明暗交替的辉光放电区。
其中包括II 负辉区、III 法拉弟暗区、IV 正柱区（等离子区）、I 阴极光膜和V 阳极辉区五个发光区。
其中前两者发光较强，以负辉区发光最强，是作为PDP 的主要发光源，等离子体显示板工作在II 、III 、IV 形成的负阻区。
汤申特(Townsend) 碰撞游离理论1. 碰撞游离的必要条件：EVE q W L L L E q W E W W ii i =⋅≥∴⋅⋅=≥ 电荷的运动距离—为：的作用下所积累的能量一个电荷在电场（分子的游离能量）（电子的积累能量），且满足：金属电极表面逸出电子∵•多级碰撞，如果碰撞能量较小但之间间隔周期很短，可能使分子游离；•电子与受激的中性分子碰撞，中性分子回到零位状态，而电子被加速能量增大，可使下一个中性分子游离；•两个受激的分子碰撞，一个交出能量，而另一个获得能量而游离。
2011年技术物理学院08级（激光方向）专业英语翻译重点！！！作者：邵晨宇Electromagnetic电磁的principle原则principal主要的macroscopic宏观的microscopic微观的differential微分vector矢量scalar标量permittivity介电常数photons光子oscillation振动density of states态密度dimensionality维数transverse wave横波dipole moment偶极矩diode 二极管mono-chromatic单色temporal时间的spatial空间的velocity速度wave packet波包be perpendicular to线垂直be nomal to线面垂直isotropic各向同性的anistropic各向异性的vacuum真空assumption假设semiconductor半导体nonmagnetic非磁性的considerable大量的ultraviolet紫外的diamagnetic抗磁的paramagnetic顺磁的antiparamagnetic反铁磁的ferro-magnetic铁磁的negligible可忽略的conductivity电导率intrinsic本征的inequality不等式infrared红外的weakly doped弱掺杂heavily doped重掺杂a second derivative in time对时间二阶导数vanish消失tensor张量refractive index折射率crucial主要的quantum mechanics 量子力学transition probability跃迁几率delve研究infinite无限的relevant相关的thermodynamic equilibrium热力学平衡（动态热平衡）fermions费米子bosons波色子potential barrier势垒standing wave驻波travelling wave行波degeneracy简并converge收敛diverge发散phonons声子singularity奇点（奇异值）vector potential向量式partical-wave dualism波粒二象性homogeneous均匀的elliptic椭圆的reasonable公平的合理的reflector反射器characteristic特性prerequisite必要条件quadratic二次的predominantly最重要的gaussian beams高斯光束azimuth方位角evolve推到spot size光斑尺寸radius of curvature曲率半径convention管理hyperbole双曲线hyperboloid双曲面radii半径asymptote渐近线apex顶点rigorous精确地manifestation体现表明wave diffraction波衍射aperture孔径complex beam radius复光束半径lenslike medium类透镜介质be adjacent to与之相邻confocal beam共焦光束a unity determinant单位行列式waveguide波导illustration说明induction归纳symmetric 对称的steady-state稳态be consistent with与之一致solid curves实线dashed curves虚线be identical to相同eigenvalue本征值noteworthy关注的counteract抵消reinforce加强the modal dispersion模式色散the group velocity dispersion群速度色散channel波段repetition rate重复率overlap重叠intuition直觉material dispersion材料色散information capacity信息量feed into 注入derive from由之产生semi-intuitive半直觉intermode mixing模式混合pulse duration脉宽mechanism原理dissipate损耗designate by命名为to a large extent在很大程度上etalon 标准具archetype圆形interferometer干涉计be attributed to归因于roundtrip一个往返infinite geometric progression无穷几何级数conservation of energy能量守恒free spectral range自由光谱区reflection coefficient（fraction of the intensity reflected）反射系数transmission coefficient（fraction of the intensity transmitted）透射系数optical resonator光学谐振腔unity 归一optical spectrum analyzer光谱分析grequency separations频率间隔scanning interferometer扫描干涉仪sweep移动replica复制品ambiguity不确定simultaneous同步的longitudinal laser mode纵模denominator分母finesse精细度the limiting resolution极限分辨率the width of a transmission bandpass透射带宽collimated beam线性光束noncollimated beam非线性光束transient condition瞬态情况spherical mirror 球面镜locus（loci）轨迹exponential factor指数因子radian弧度configuration不举intercept截断back and forth反复spatical mode空间模式algebra代数in practice在实际中symmetrical对称的a symmetrical conforal resonator对称共焦谐振腔criteria准则concentric同心的biperiodic lens sequence双周期透镜组序列stable solution稳态解equivalent lens等效透镜verge 边缘self-consistent自洽reference plane参考平面off-axis离轴shaded area阴影区clear area空白区perturbation扰动evolution渐变decay减弱unimodual matrix单位矩阵discrepancy相位差longitudinal mode index纵模指数resonance共振quantum electronics量子电子学phenomenon现象exploit利用spontaneous emission自发辐射initial初始的thermodynamic热力学inphase同相位的population inversion粒子数反转transparent透明的threshold阈值predominate over占主导地位的monochromaticity单色性spatical and temporal coherence时空相干性by virtue of利用directionality方向性superposition叠加pump rate泵浦速率shunt分流corona breakdown电晕击穿audacity畅通无阻versatile用途广泛的photoelectric effect光电效应quantum detector 量子探测器quantum efficiency量子效率vacuum photodiode真空光电二极管photoelectric work function光电功函数cathode阴极anode阳极formidable苛刻的恶光的irrespective无关的impinge撞击in turn依次capacitance电容photomultiplier光电信增管photoconductor光敏电阻junction photodiode结型光电二极管avalanche photodiode雪崩二极管shot noise 散粒噪声thermal noise热噪声1.In this chapter we consider Maxwell’s equations and what they reveal about the propagation of light in vacuum and in matter. We introduce the concept of photons and present their density of states.Since the density of states is a rather important property，not only for photons，we approach this quantity in a rather general way. We will use the density of states later also for other(quasi-) particles including systems of reduced dimensionality.In addition,we introduce the occupation probability of these states for various groups of particles.在本章中，我们讨论麦克斯韦方程和他们显示的有关光在真空中传播的问题。
光子的能级跃迁涉及到原子物理学的知识，主要有三种过程，分别是自发辐射、受激吸收和受激辐射。
自发辐射过程：处于高能级E的一个原子自发的向低能级E跃迁，并发射一个能量为hv的光子，这种过程称为自发跃迁，由原子自发跃迁发出的光被称为自发辐射。
自发辐射的光子是自发产生的，其辐射是独立的。
受激吸收过程：处于低能态E的一个原子，在频率为v的辐射场作用下，吸收一个能量为hv的光子并向高能态E跃迁，这种过程称为受激吸收跃迁。
这个过程是非自发的，需要外来光照射，而且能够增强光的强度。
与原光子性质、状态完全相同。
受激辐射过程：处于上能级E的原子在频率为v的辐射场作用下，跃迁至低能态E ，并辐射一个能量为hv的光子。
这个过程只有在外来光子的能量恰好等于能级差时才会发生，受激辐射所发出的光子与外来光子的特性完全相同，即频率相同、相位相同、偏振方向相同、传播方向相同。
以上信息仅供参考，建议查阅物理书籍或咨询物理专业人士以获取更深入的了解。
TPO8 Lecture 4 ChemistryPro: So, are there any questions?Stu: Yes, um, Professor Harrison, you were saying that the . What exactly does that mean? I mean I understand how it organizes the elements but where’s the prediction?Pro: Ok, let’s look at our periodic table again. Ok, it groups elements into categories that , right?Stu: Uh-huh. Pro: And it is arranged according to increasing atomic nu mber, which is…Stu: The number of protons in each atom of an element.Pro: Q1Right, well, early versions of the periodic table had gaps, elements. Every time you had one more proton, you had another element. And then, oops, there’d be an atomic number, for which there was no known element.And the prediction was that an element with that atomic number existed somewhere, but it just hadn’t been found yet. And its location in the table would tell you what properties it should have. It was really pretty exciting for scientists at that time to find these missing elements and confirm their predictive properties.Q1Um, actually, that reminds of a ... of a very good example of all these, element 43. See on the table, the symbols for elements 42 and 44. Well, in early versions of the table, there was no symbol for an element 43 protons because no element with 43 protons had been discovered yet. So the periodic table had a gap between elements 42 and 44.And then in 1925, a team of chemists led by a scientist named Ida Tacke claimed that they had found element 43. They had been using a new technology called X-ray , and they were using this to examine an ore sample. And they claimed that they’d found an element with 43 protons. And they named it Masurium.Stu: Um, Professor Harrison, then, how come in my periodic table here, element 43 is Tc, that’s Technetium, right?Pro: Ok, let me add that. Actually, um, that’s the point I’m coming to. anyone believed that Tacke’d discovered a new element. X-ray spectroscopy was a new method at that time. And they were never able to isolate enough Masurium to have a weighable sample to everyone of the discovery. So they were discredited.But then, 12 years later in 1937, a different team became the first to an element using a cyclotron. And that element had…Stu: 43 protons?Pro: That’s right, but they named it Technetium to Q3emphasize that it was withtechnology. And people thought that synthesizing this element, making it artificially was the only way to get it. We still hadn’t found it.Now element 43, whether you call it Masurium or Technetium, is radioactive. Why does that matter? What is true of a radioactive element?Stu: It , it turns into other elements. Oh, so does that explain why it was missing in the periodic table?Pro: Exactly, because of its radioactive decay, element 43 . And therefore, if that ever had been on Earth, it would have decayed ages ago. So the Masurium people were wrong, and the Technetium people were right. Right? Well, that was then, now we know that element 43 does occur naturally. It can be naturally Uranium atoms that have spontaneously split. And guess what, the ore sample the Masurium group was working with had plenty of Uranium in it enough to split into of Masurium. So Tacke’s team might very well have found small amounts of Masurium in the ore sample. Q4 It’s just that once was generated from split Uranium, it decayed very quickly.Q6And you know here’s an , Ida Tacke, the chemist led the Masurium team, well, she was the first to suggest that Uranium could break up into smaller pieces, but she d idn’t know that that was the defense of her own discovery of element 43.Stu: So is my version of the periodic table wrong? Should element 43 really be called Masurium?Pro: Q5Maybe, but you know it’s hard to tell after all this time, if Ida Tacke’s group did discover element 43. They didn’t, um, publish enough detail on their methods or instruments for us to know .But I’d like to think element 43 was discovered twice. As Masurium, it was the first element discovered that occurs in nature only from spontaneous fission, and as Technetium, it was the first element discovered in a laboratory. And of course, it was an element the periodic table let us to expect existed before anyone had found it or made it.。
