Simulating the electronic devices by computers , can forecast the real performance of devices before experiments . by discussing the effects of changing the size and material , we can reduce the blindness and times of experiments , and save the experiment outlay . computer simulation of field emission cathodes is an important research topic 利用计算机来模拟电子器件的性能,可以在实验前预测器件的性能,探讨器件结构尺寸、材料等因素对器件特性的影响,减少实验的盲目性,从而可以减少实验次数、节约实验经费,因此关于场发射阴极的计算机模拟也是一个十分重要的研究课题。
With the development of high power microwave tube , the theoretical and experiment investigation of the high performance cathode have been conducted . the research work includes how to prepare the high performance cathode and the effect of the based metal on the cathode emission , the measurement of the inner and surface fine structures of the cathode , the discussion of emission mechanism of thermionic cathode . after a lot of experiment , we finally determined the cathode preparation with an excellent emission 为了适应大功率微波管的发展，本文展开了对高性能(大电流密度、长寿命)阴极的研究，研究工作包括阴极制备工艺、钡钨阴极基金属对阴极发射性能影响、以及钡钨阴极基底内部结构无损检测及表面形貌检测、钡钨阴极发射机理探讨及应用四个方面的实验和理论的研究。
Tow types of fuel - cell models can be distinguished : microscopic and macroscopic . this paper adopt agglomerate microscopic model to analyze the fuel cell ' s performance . according to the computation , it can be concluded that the performances are determined by the thickness of the electrode , the effective ionic conductivity , the radius of agglomerate and other parameters 对燃料电池单体，建立了微观的数学模型? ?聚块模型，用nenmanbandj方法计算熔融碳酸盐燃料电池阳极和阴极的过电位，分析了各种参数的影响，对电极的制备，提高单电池的性能，有一定的指导意义。
Special attention is paid to the consequences of methanol crossover in cathode reaction and cathode over - potential . good agreement is found between simulations and experiments in regard to the v - i character of dmfcs . based on the theory of parallel electrode reaction , it becomes possible to obtain quantitatively the value of over - potential caused by methanol crossover , which is either implicit or not included in the overall cathode over - potential in previous models 该模型涵盖了dmfc中的主要物理化学过程，包括：甲醇水溶液在膜电极内的扩散、对流和电迁移；质子在阳极催化剂层和阴极催化剂层内的传递；氧气、水蒸汽在阴极的扩散；阳极催化剂层内的甲醇氧化反应动力学；以及阴极催化剂层内的氧还原和甲醇氧化反应动力学。
In this paper ， first , the author drew some important conclusions by analyzing several technical factors and experimental conditions which would have great influence on the quality of diamond thin films during mpcvd process ， including gas proportion ， the power of microwave ， the plasma ' s location , the nucleation technique , etc . . finally ， the author has successfully deposited nanocrystalline diamond thin films with 300nm crystal particles on the slick surface of silicon by using ch4 / h2 gases in the mpcvd system ， and the nanocrystalline diamond thin films was proved to have good field emission performance . all these researches will make the foundation for the field emission cathode of diamond films 本论文中，作者分析了mpcvd方法中气源成分比、微波功率、等离子体球的位置、成核技术等各种工艺条件对金刚石薄膜质量的影响，并总结得到了一些有意义的结论；同时，在自行研制的mpcvd沉积系统上，于4 - 7kpa 、 1000左右的热力学条件下，采用ch4 / h2气源气氛在光滑的硅衬底上制备出了晶粒尺寸在300纳米以下的纳米晶金刚石薄膜，测试得到了较好的薄膜场致电子发射性能，为金刚石薄膜场致发射冷阴极的研究工作打下了实验基础。
The current density jdiv reaches 50 a / cm2 at 850 b , which has reached the best emission level in the world while its sc2o3 . content reduced . the emission of e3 cathode is non - uniform and the emission capabilities of e1 and e3 cathode are lower than s2 . emission capability of y4 and y6 cathode is similar as that of normal ba - w cathode 测试了阴极的电子发射能力,实验结果显示: y3阴极的发射性能优异, 850 b时直接偏离点电流密度jdiv达到50a / cm2 ,与sc - w基阴极的最好发射记录处在同一个水平; e3阴极的发射不均匀, e1和e3阴极的发射能力均低于s2阴极; y4和y6阴极的发射水平与普通ba - w阴极相接近。
The main work and conclusion for this paper is as following : according to the flashover test results of several kinds of iced insulators under positive voltage and negative voltage , this paper obtained : for the single porcelain insulator , the single glass insulator and the composite insulator bridged completely by icicle , the metal cathode ' s strong ability of emission electron is the primary reason that results in the lower negative flashover voltage ; the position difference of the high resistance district in method anode side results in that porcelain insulator cluster and glass insulator cluster have an evident effect of polarity ; when less ice and no icicle at the brim of the sheds , due to numerous non - polar arcs on the composite surface , the effects of polarity of composite insulator was lost using the test method of the average flashover voltage in the freezing period , dc flashover performances were investigated of several insulators with some typical structures and different material 本文的主要工作和结论如下：在人工气候室内，根据不同覆冰绝缘子正、负极性下的闪络试验结果，得出负极性电弧金属阴极的强电子发射能力造成了单片瓷、玻璃绝缘子及被冰凌桥接的合成绝缘子有较低负极性冰闪电压；正极性电弧金属阳极侧产生高电阻区所处位置的差异使得瓷和玻璃绝缘子串具有明显的极性效应；覆冰较少时，合成绝缘子表面出现数量较多的非极性电弧使合成绝缘子无极性效应。利用覆冰期内平均闪络电压的试验方法，对不同材质和结构的绝缘子在覆冰、低气压和污秽共存环境中的直流闪络特性进行了研究。试验结果表明，直流平均闪络电压随着海拔的升高、覆冰量的增加以及污秽度的增加而降低，且其特征指数与绝缘子结构、覆冰量、覆冰状态、污秽度等有关。
In view of the problems existing in the research and producing of the iii image tube in our country , a study of the iii image intensifier have been carried on , the work introduced in this dissertation is as following : ( 1 ) the way to evaluate the properties of nea photocathodes has been proposed . that is using the spectral response and xps measurement results to determine the property parameters of nea photocathodes 本文针对国内在三代管研制方面存在的问题，围绕“三代像增强器研究”作了以下工作： ( 1 )研究nea光电阴极的性能评估，提出通过光谱响应和变角xps测试确定阴极特性参量，从而有效地解决nea光电阴极的性能表征问题。
( 3 ) the spectral matching factor of nea phothocathodes for reflecting spectrum of objects under night sky radiation has been studied . the spectral matching factors of typical phothocathodes , such as gaas nea photocathode , s _ ( 251 ) and s _ ( 252 ) photocathode , are calculated and compared . the factors give the explanation of high detection performance of the low - light - level night vision equipments ( 3 )研究了nea光电阴极和夜天光照射下景物反射辐射的光谱匹配系数，计算了gaasnea光电阴极的光谱匹配系数，并将之与s _ ( 251 ) 、 s _ ( 252 )光电阴极的计算结果作了比较，揭示了三代微光夜视仪具有优良探测性能的原因。
However , the most commonly used x - ray sources didn " t change much no matter in structure or theory , still using thermionic cathodes as electron sources . such conventional x - ray tubes have some defaults , such as big volume , low frequency response , demanding for supply to cathode that was also brittle 目前使用的x光源的基本特点是采用热电子发射形式即采用热灯丝作为电子发射源，在高压加速下轰击阳极产生x射线，这样的光源体积较大，需要加热阴极的电源，且对频率响应慢。
