百叶窗式倍增系统场分布的二维有限元模拟计算

本文应用二维有限元方法对光电倍增管的百叶窗式倍增系统在有栅网和没有栅网的电场分布进行了计算，并根据计算结果提出了提高二次电子发射的方法。     

栅控电子枪栅网抗振优化设计

栅控电子枪栅网与阴极间的精密设计结构和栅网对束流的调整作用决定其设计结构必须具有良好的抗振可靠性.使用有限元模拟技术对电子枪栅网进行模态分析,模拟分析了不同栅网尺寸的模态频率和模态振型,并对影响模态频率的因素进行探讨,为栅网的优化设计提供了参考.     

碳纳米管冷阴极电子枪栅网电子通过率的仿真及实验

本文在栅网结构碳纳米管冷阴极电子枪原型器件的基础上,研究了栅网通过率对冷阴极电子枪阴极发射和电子通过率的影响。首先通过计算机仿真了栅网通过率对阴极发射电流及阳极电流的影响,在其他条件相同的情况下,栅网通过率为80%左右时可得到最大阳极电流;其次根据仿真结果加工了两种不同栅网通过率的电子枪原型并进行了测试,得到的实验结果与仿真基本一致,最后从理论上对实验结果进行了分析,对进一步研究冷阴极电子枪提供了技术依据。     

球面栅网后加速透镜的研究

本文分析了栅网后加速透镜系统的性质,计算了栅网尺寸对栅网透镜的偏转放大率、偏转非线性和光栅畸变的影响.所提供的数据曲线可用作实际设计.     

栅网表面处理工艺

控制栅栅网是栅控脉冲行波管的关键部件之一。这种栅网是由钼片经电火花加工制成的。制成的栅网的网丝上常常有毛刺和其它黑色附着物。这些附着物不易清除干净并因此往往造成管子打火,栅极截获电流偏大,从而影响管子的性能和成品率。因此,设法将栅网表面处理干净是十分重要的。 清除栅网表面附着物目前通常用手工去除毛刺和金刚砂超声处理,但效果较差。为了寻求一种较有效的处理工艺,我们先用离子探针和俄歇电子谱仪对网丝表面进行了组     

条纹相机中栅网的特性研究

栅网是条纹相机等电子光学仪器的重要组成部件。通过使用有限差分法对栅网的丝径、网孔进行精细建模,分析了栅网对均匀电场的扰动以及对电子运动的子透镜效应;使用电子碰撞自由程Gryzinski理论研究了电子和栅网碰撞的二次电子发射问题。结果发现,对于条纹相机中常用的10,33,50line/mm栅网,其结构参数的不连续性对均匀电场的扰动分别为0.31%、0.07%、0.04%;对于入射能量为15keV的电子,栅网金属原子Ni、Cr和Cu的非弹性散射碰撞自由程分别为6.85,10.34,7.25nm,碰撞很难产生二次电子发射。研究结果对电子光学仪器的设计和栅网参数的优化具有参考意义。     

大曲率半径球面栅网加工工艺

讲述采用栅网光刻-成形球面-翻边一定型工艺解决了带翻边球冠形栅网加工的问题,与常规电火花加工栅网方法相比,该方法具有省时、高效、低成本的特点.     

条形离子源栅网设计及优化

为克服传统圆形离子源刻蚀基片数量较少、产能较低的劣势,提高离子源栅网的精度、稳定性及使用寿命,设计出一种用于离子束刻蚀的条形离子源栅网。采用ANSYS18.2对栅网进行热应力仿真模拟分析,为进一步增强离子源栅网性能,通过加工前后的真空退火处理,达到改善栅网使用性能、提高稳定性和延长使用寿命的效果。将两种栅网装载至M431-9/UM型离子束刻蚀设备进行实验验证,结果表明相比条形腰孔曲面型栅网,条形圆孔平面型栅网在热应力下形变量更小,更符合离子源对精度、稳定性及使用寿命的要求。     

栅控电子枪的热特性分析

利用ANSYS 有限元软件分析了栅控电子枪的热特性,包括稳态温度场计算和结构热形变,其中稳态温度场计算包括电子枪和栅网的温度分布以及栅网因电子截获而引起的温升。并利用行波管设计软件TWTCAD 分析了热形变前后电子光学系统性能的变化。同时还采用热电偶法得到了实际栅网的表面温度,试验结果与仿真结果基本一致,证明了热分析结果的有效性。     

CO_2激光器偏振栅网的制造

本文叙述了在CO_2激光器偏振管中,用金属起偏栅网代替氯化钠起偏片后能获得同样的偏振光。金属起偏栅网与常用的氯化钠起偏片相比,其优点是对光方便、制造简单、简化了制管工艺,缩小了偏振管的管长和体积,减轻了重量。本文着重介绍金属起偏栅网的制造工艺。     

Validity and Accuracy of Equivalent Circuit Models of Passive Inductive Meshes. Definition of a Novel Model for 2D Grids

Accuracy of equivalent circuit models of periodic grids is investigated in amplitude and phase in the visible region. The grids studied here are one-dimensional (1D) and two-dimensional (2D) inductive thin metal meshes. They are located in free space and are illuminated by a plane wave under normal incidence. The range of validity and the accuracy of conventional circuit models are defined by comparison with rigorous results obtained with the Finite-Difference Time-Domain (FDTD) method. In particular, it is shown that electrical models of 1D grids are accurate, whereas equivalent circuits of 2D grids should be used very cautiously. Then, a new formulation is proposed to overcome this major drawback. In the non-diffraction region, the agreement between our model and the FDTD results is within 2% for the power reflectivity and 1° for the phase over a very wide range of strip widths.     

A new approach to diffraction analysis of conductor grids. I.Parallel-polarized incident plane waves

Diffraction analysis is presented for infinite planar conducting-cylinder grids illuminated by normally incident (parallel-polarized) plane waves, the electric fields of which are parallel to the cylinder axes. The Green's function kernel integral equations are used for the induced currents, which are based on the equivalent waveguide theory and solved for the currents by the moment method. This is a universal analysis approach, applicable to infinite planar grids made of conducting cylinders of arbitrary cross section, uniform or periodic, dense or sparse, single layer or multilayer     

A new approach to diffraction analysis of conductor grids. II.Perpendicular-polarized incident plane waves

For pt.I see ibid., vol.37, no.1, p.84-88 (1988). Diffraction analysis is given for infinite planar conducting-strip grids illuminated by normally incident (perpendicular-polarized) plane waves, the electric fields of which are perpendicular to the strip axes. Iris-surface electric field integral equations are used which are based on the equivalent waveguide theory, and then the electric field is solved for using the moment method. This is a universal approach applicable to infinite planar grids made of conducting strips of rectangular cross section, uniform or periodic, dense or sparse, single layer or multilayer     

Passive equivalent circuit of FDTD: an application to subgridding

The finite difference time domain (FDTD) method gives accurate results for many problems but uses a large amount of computer memory and time. This can be reduced by using subgrids (fine grids) only around critical areas in the problem domain. The fields within the coarse and fine grids are found using standard FDTD equations, while at the boundary of the subgrid, interpolation of coarse grid fields is utilised. However, a simple interpolation as reported in literature exhibits late time instability. The authors present a stable scheme of updating the subgrid boundary fields by replacing the grid discontinuity with an equivalent circuit. The stability and accuracy of this new scheme is demonstrated through calculation of the cutoff wavelength of a dielectric slab loaded waveguide for various slab thickness     

同轴馈电耦合微带贴片天线的时域有限差分法分析

提出一种融合曲线坐标和直角坐标的区域网格划分方法。在同轴线区域采用曲线坐标网格,用以代替传统的阶梯剖分,在其它区域及边界上采用直角坐标网格,从而极大地提高了计算效率。同时,在时域有限差分法中还采用了非均匀网格划分,PML吸收边界和Prony外推法等技术,对同轴馈电的耦合微带贴片天线进行了分析。     

Synthesis of bandpass grid filter for linear polarized millimeter wave

A method based on equivalent circuit and transmission line model is proposed to design narrow bandpass grid filters in short millimeter wave. Several bandpass filters with 2, 3 or 4 element inductive wire grids in the 70GHz region have been designed with Butterworth or Chebyshev characteristic for linear polarized wave. The agreement between measurement and design theory is good and this proves the rationality and practicality of our design theory.     

Ultra-Wideband Wave Reactances of Capacitive Grids

The accuracy of transmission line models of two-dimensional freestanding capacitive grids is studied on a very wide frequency band. The grids are of infinite extent in the transverse directions and are illuminated by a linearly polarized normally incident plane wave. Comparison with reference results deduced from Finite-Difference Time-Domain (FDTD) simulations allows determining the range of validity of commonly used equivalent circuits It is shown that their accuracy strongly depends on the dimensions of the grids and the operating wavelength. Although very convenient, their implementation for calculating the frequency response of multi-layer systems could lead to unreliable results. Two closed-form new models are thus proposed. The first one results from an optimized expression of the well-known Marcuvitz's impedance, and the second one involves a series resonant LC circuit shunted by an additional capacitance. Both formulations are very accurate for a wide range of grid geometries and over the whole visible region (wavelength > grid constant).     

A full-wave analysis of offset reflector antennas with polarizationgrids

A full-wave analysis is presented of offset reflector antennas with polarization grids which uses the equivalent grating approach proposed by the authors (ibid., vol.AP-35, p.367-71, Apr. 1987). Two types of antenna are compared: one has a parallel straight strip grating (grid A) and the other has a curved strip grating (grid B) whose pattern is designed so that the antenna system does not generate a cross-polarized component. The key future method is the definition of the equivalent grid. This method quantitatively evaluates the scattering, includes a physical interpretation of the phenomena and gives a physical interpretation of the phenomena and gives a suggestion for the design of the strip patterns. Cross-population suppression effects are quantitatively evaluated as functions of the strip parameters, the size and the location of the grid. It is noted that the cross-polar peaks of the patterns with grid A move with the tilt angle of the grid. The mechanism of this movement is also explained     

子阵模块不同排列对相控阵天线辐射特性的影响分析

辐射单元矩形栅格排列是相控阵天线中最简单的排列方式,也是最常用的一种排列方式。它是把整个阵面划分成许多矩形栅格,每个辐射元占据一个自然格或栅格的交点。而本文对子阵模块间采用三角形栅格而子阵模块内采用矩形栅格的排列方式进行了分析,通过理论分析验证这种排列方式比普通矩形栅格排列有较大优势。     

Reflectance Measurement of Lossy Metal Meshes in the Millimeter-Wave Range

The method of power reflectance measurement of small lossy metal meshes is suggested by evaluating the measured reflection coefficient in the vicinity of a resonance mode of quasi-optical resonator. The resonator is described by the equivalent circuit that includes coupling ohmic losses of the mesh. The multi-points reconstructing algorithm is suggested to restore power reflectance. This particular technique is suitable for reflectance measurements of lossy metal meshes and wire grids having overall small dimensions which are not relevant when employing standard free space techniques. Its validity is illustrated by reflectance measurements in W-band.