光电二极管的特性的研究

本文通过对用光电转换综合测量仪所测出的光电二极管的特性的实验数据、特性曲线的讨论,验证了光电二极管的光照特性、伏安特性以及光谱特性。     

纳米CaCO3作固硫剂的基础研究

本文主要研究纳米碳酸钙与固硫有关的微观物理特性和固硫特性。研究表明,纳米碳酸钙有较好的利于固硫反应的微观物理特性和固硫特性,但固硫效果的好坏同结构特性有关,并且固硫特性受温度条件的支配影响,纳米碳酸钙用作喷钙吸收剂已具备一定的实用意义     

基于Mueller矩阵的目标偏振特性分析

目标Mueller矩阵反映了光波在传播过程中偏振态的变化,其包含与目标自身有关的起偏、退偏等偏振特性。为进一步研究目标Mueller矩阵特性,通过将光波传播过程转化为相关半正定二次型函数实现偏振态变化线性运算的方法,定义目标净退偏特性和可以综合评价目标起偏特性和退偏特性的偏振度PΔ,并证明了其在偏振探测目标识别和偏振特性分析中的有效性。最后利用实验测量了不同入射角、粗糙度铝板的Mueller矩阵,通过定义粗糙度对目标偏振特性的影响因子Q和目标偏振特性随入射角变化的稳定性S,分析了入射角和粗糙度对目标Mueller矩阵特性的影响。     

运动状态对卫星多谱段光学特性的影响分析

综合考虑卫星的背景特性、材料特性、结构特性和轨道特性,研究了在轨运行卫星存在的自旋稳定、三轴稳定和"翻滚"三种运动状态对卫星光学特性的影响。基于光辐射理论,结合探测器的性能参数,建立了自旋稳定、三轴稳定和"翻滚"三种运动类型卫星的多谱段光学特性计算的数学模型,并进行了实验验证。以海洋一号卫星和实践二号卫星为例,进行了运动状态对卫星多谱段光学特性影响的仿真分析。仿真结果表明,不同运动状态的卫星多谱段辐射特性存在较大的差异。分析结果可为卫星的探测和辨识提供一定的参考价值。     

生物质与煤矸石混烧特性实验研究

采用热重分析仪,以20℃/min的温升速率对煤矸石、玉米秸秆以及二者的混合物进行燃烧特性实验,得到了燃烧的特性参数,再通过动力学分析得到了燃烧的活化能等动力学参数.研究结果表明,煤矸石的着火特性、综合燃烧特性差,玉米秸秆着火特性、综合燃烧特性较好.煤矸石和玉米秸秆混合物的燃烧特性取决于混合物中各物质所含的比例,混合物中玉米秸秆的比例越高,综合燃烧特性越好.     

吸收性介质内气泡的表观辐射特性研究

气泡的存在对介质的辐射传输特性具有重要影响。本文基于广义MIE理论计算了气泡在吸收性介质内的辐射特性。研究了介质的复折射率虚部对气泡表观辐射特性的影响以及0.2~200μm可见光及红外波长范围内介质水的吸收特性对气泡粒子系散射系数和吸收系数的影响。结果表明,随着粒子尺度参数的增大,介质吸收对气泡表观辐射特性的影响相应增大,忽略介质吸收将带来很大误差;当波长大于2μm时,介质水的吸收特性对气泡的散射特性影响不能忽略。     

InGaAsP/InP边发光管特性的研究

用液相外延技术生长的外延片,制成了SiO2条形限制的InGaAsP/InP边发光管,100mA下光功率1mW,最高值1.3mW,发射波1.31μm,半宽860A。研究了外延材料特性(如p-n结位置,有源层厚度和浓度)对器件光功率,光谱特性,和Ⅰ-Ⅴ特性的影响。有源层厚度(d)对光功率和光谱半宽有重要影响,p-n结不偏位的器件,光谱特性为单一的长波长发射蜂,具有正常的Ⅰ-Ⅴ特性。p-n偏离有源层的器件,光谱特性除长波长发射峰外,尚有9700A的InP发射峰,其Ⅰ-Ⅴ特性具有异常特性,导通电压>0.9V。     

眼睛对目视光学系统性能的影响

显然,如果眼睛是光学系统的组成部分,则在评定系统的性能时必须考虑眼睛的特性,即使是刚开始设计也是这样。肉眼决不会受衍射的限制,但它有许多其他特性,这些特性会影响到把眼睛作为最后接收器的光学系统的设计。本文将讨论有关人眼的三个特殊问题:眼睛尺寸大小特性;眼睛的光度特性;眼睛的分辨率。     

内螺纹管管型结构对管内流动阻力特性的影响

对不同结构的内螺纹管内空气-水两相流动的阻力特性进行了实验研究,从实验方面得出了影响内螺纹管阻力特性的主要几何参数(螺纹高度,螺纹升角,螺纹宽度等)对内螺纹管阻力特性的影响规律。结合实验现象,引入了研究内螺纹管阻力特性的并联管路模型,最终得出适用于不同结构内螺纹管的阻力特性半理论经验公式。通过该公式可以较好地反映出各个几何参数对内螺纹管阻力特性的影响规律。     

弹性液滴的复杂界面特性模拟

弹性液滴(弹性膜包裹黏性流体)在流场中的变形、运动等界面动力学特性显著影响液滴内外流体间的物质输运等特性,而液滴界面的弹性、抗弯特性等复杂力学性质是影响其动力学特性的决定因素之一。基于FTM(Front tracking method),建立了弹性液滴在流场中变形运动的三维模型,考虑界面弹性、抗弯特性等复杂力学性质,重点分析了抗弯特性对液滴变形及界面内应力分布的影响。结果表明抗弯特性使液滴变形量降低,减小界面内最大应力和最小应力的值,抑制界面上波浪形褶皱条纹的形成,增强液滴界面稳定性。     

X射线皮秒变象管分幅相机研究

本文介绍了我们提出的一种新的实现皮秒分幅摄影的技术方案,其优点是对控制线路要求不高,给出了用计算机对此方案进行数值模拟的结果和新设计的用于这种分幅方案的变象管特性,用直流X射线源测出该变象管的静态空间分辨率为20lp/mm。用激光打靶产生的脉冲X射线测量了相机动态特性,已得到了四幅动态像,每幅曝光时间150ps,空间分辨率3lp/mm。     

Modeling of life deterioration by ion bombardment of a dispenser cathode coated with an Ir/W film

We have developed the calculation method for ion bombardment traces. When an M type dispenser cathode is operated in a cathode ray tube (CRT), the surface coating film is subjected to ion bombardment due to ionized residual gas. With long-time use, the coating film is dissipated and a change to an S type occurs. This occurrence of an S type causes a deterioration of emission and focus characteristics. A method for calculating the life time dependency of the shape of ion bombardment traces using the degree of vacuum in the tube, the grid voltage, and the cathode current was studied. The calculated results and measured results were in close agreement. As a result, it was confirmed that modeling is possible using (1) an electron and ion beam trajectory calculation program, and (2) formulas for calculating the ionization cross-section and sputtering yield.     

Notes on technique in the laboratory determination of e/m for electrons by the magnetron method

The paper concerns a fairly common basic error in the formulation of the laboratory experiment on the determination of e/m for electrons by the magnetron method, in that a diode is replaced by a tube with several grids connected to the cathode. It is shown that in that case the experimental value for the specific charge as given by the usual formula is dependent on the plate voltage. Above some plate voltage (the critical value), the relationship to the plate voltage becomes linear, so a value exceeding the tabulated value by a substantial factor can be obtained by increasing the plate voltage appropriately. On the other hand, the tabulated value is obtained only for a single plate voltage. However, even this value lies in the range of voltages where the working formula is inapplicable. Therefore, this approach is simply one of adjusting the observed result to the tabulated value.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 79–88, April, 1976.     

Anisotropic selfdiffraction in BaTiO3

A comparison of the operating characteristics of the high-voltage regime of the discharge in a hollow-cathode tube, the hollow-canthode discharge (HCD) and the discharge to a plane cathode are presented. The disappearnce of the hollow-cathode effect and the transition to a high-voltage discharge after inserting several anode rods into the cathode cylinder is exhibited. The similarity between the operating characteristics of such a high-voltage discharge and of a plane cathode discharge is shown. The loss of ions at the anode rods, as well at insulators or floating conductors is believed to be the reason behind the increase of the operating voltage and the disappearance of HCD characteristics. Practical means of increasing the operating voltage are mentioned.On leave from the Institute of Fluid Flow Machines, Polish Academy of Sciences, Gdansk-Wrzeszcz, Fiszera 14, Poland. This work was supported by the Alexander-von-Humboldt Foundation and the Deutsche Forschungsgemeinschaft (DFG)     

真空微电子器件的数值模拟计算与分析

本文用数值方法和场致发射的福勒—诺德海姆公式计算了薄膜场致发射阴极(TFFEC)的伏安特性和其应用于平板显示系统的空间扩展特性以及格雷型场效应管的时间响应特性 通过计算得到了TFFEC在不同失端和表面形状情况下的伏安特性曲线,并分析了阴极结构的一致对其发射的均匀性和稳定性的影响。应用TFFEC的新型平板显示系统,其空间分辨能力与阳栅距、栅极电压有很大关系。格雷型场效应管具有皮秒级的响应时间。     

A flexible carbon nanotube field emitter fabricated on a polymer substrate by a laser separation method

The fabrication of a sparsely networked carbon nanotube (CNT) thin film on a polycarbonate substrate as the conductor electrode and the emitting cathode by a newly proposed laser separation method is reported. Based on this approach, numerous surface protruding tube tips can be structured straightforwardly, which results in favorable field-emission characteristics. A flexible field emitter with a low turn-on voltage of 1.0 V/μm can be obtained. This method also demonstrates the abilities for fabricating a film with precision patterns and varying CNT concentrations as well as the flexibility of direct film formation on a curved surface. Moreover, all fabrication steps are executed in the ambient environment and at room temperature.     

X射线在影象增强器中背向散射特性的研究

本文用蒙特卡罗方法模拟了轫致辐射Ｘ射线在影象增强器中的背向散射特性。针对Ｘ线源管电压为３０－１２０ｋＶ的轨致辐射入射，给出了背向散射光子的角分布及能谱分布；同时，还给出了背向散射光子的平均能量和平均出射角与管电压的关系以及吸收光子数和直透光子数与管电压的关系。     

X‐ray tube spectral measurement method for quantitative analysis of X‐ray fluorescence analysis

Lα and Lβ X‐ray fluorescence spectra of a lead metallic sheet were measured using an energy dispersive X‐ray spectrometer by changing the X‐ray tube voltage and the material of the primary filter. The Lα to Lβ intensity ratio changed from Lα: Lβ = 3: 1 at 15 kV to Lα: Lβ = 1: 1 at 50 kV depending on the X‐ray tube voltage and the filter. The scattered X‐ray spectra of an acrylic slab instead of the sample in the sample holder were measured by changing the applied voltage and the material of the primary filter. The calculated values of the Pb Lα/Lβ intensity ratio of the metallic sheet using the Shiraiwa–Fujino formula by inserting the scattered X‐ray spectra of an acrylic plate as incident X‐ray spectra and the fundamental parameters taken from the Elam database were in good agreement with the experimental ones. We conclude that we can obtain an incident X‐ray spectrum approximately by measuring the scattered X‐ray spectrum without measuring the direct incident beam. Copyright © 2010 John Wiley & Sons, Ltd.     

行波前置短磁聚焦飞秒条纹管设计

设计了一款长度为265mm的飞秒条纹管。采用短磁聚焦透镜和行波偏转板,并将行波偏转板置于磁透镜之前以提高偏转灵敏度。采用蒙特卡罗方法对阴极表面理想点和阴极狭缝发射的光电子初始参量进行了模拟抽样,用CST软件的Particle Tracking模块模拟跟踪了光电子的运行轨迹,统计分析了光电子在最佳像面上的位置分布和渡越时间,给出了光电子在最佳像面上的点扩展函数和调制传递函数。计算结果显示,所设计的条纹管阴极有效尺寸达到6mm,放大率为2.4~2.5,动态空间分辨力大于55lp/mm。经保守估算,条纹管的时间分辨力有望达到245fs。     

空心阴极直流放电的二维自洽模型描述和阴极溅射分析

建立了空心阴极放电的二维自洽理论模型,理论研究了气压为50—120Pa,电压为150—300V的范围内Ar空心阴极放电特性、粒子密度和电离速率空间分布,特别考察了影响阴极溅射分布有关因素:阴极面上的电场、离子流和离子密度的沿阴极截面的空间分布.研究结果不仅证实了在所讨论的范围内,空心阴极效应明显存在而且发现归一化电离速率的空间分布形状强烈依赖于气压.通过研究电场、离子流和离子密度的空间分布解释了空心阴极溅射型离子激光器中不均匀阴极溅射的现象来源于阴极面附近的电场、离子流和离子密度的不均匀分布 关键词： 空心阴极放电 自洽模型 气体激光 阴极溅射