量子点-腔系统耦合强度对非相干抽运的响应

用量子主方程理论研究了量子点-腔耦合系统。为了说明理论模型,分析了一个量子点微柱腔强耦合(SC)实验。经研究发现耦合系统在稳态时抽运产生一个新的强耦合标准,抽运可以抑制或者增强强耦合;腔发射谱双峰结构并不是强耦合的明确特征,它还依赖于非相干抽运。研究表明,强耦合经常出现变相的单峰而弱耦合(WC)出现双峰结构与系统所控制的参数值密切相关。激子抽运增加时,腔发射谱由双峰逐渐变成增宽的单峰最后变成窄的单峰;腔衰减率增加时,均为双峰结构的腔发射光谱经历了从强耦合到弱耦合的转变。量子点腔失谐系统有效耦合强度与非相干抽运密切相关。     

一种能适应低电压大功率应用需求的毫米波耦合腔慢波结构

本文在分析传统耦合腔慢波结构的基础上,提出了一种具有低电压大功率特点的耦合腔慢波结构。该慢结构可以充分利用传统耦合腔慢波结构的成熟工艺,是一种非常有发展前途的毫米波慢波结构。     

一种基于三角形耦合环的可调同轴腔滤波器

提出并研究了一种用于小型化同轴腔可调带通滤波器的新型腔间耦合结构,这种结构可使滤波器绝对带宽在工作频率范围内几乎保持常数.新型腔间耦合结构由三角形耦合环和矩形耦合窗复合组成,它能在保持腔间耦合度的情况下控制腔间耦合带宽随工作频率的变化,从而使可调滤波器在工作频段内的高低端绝对带宽保持不变.文中在分析同轴腔内电磁场分布的基础上得出了带宽恒定条件下的结构参数约束范围.采用这种耦合结构设计并制作的3腔同轴腔可调滤波器得到了56%的调谐范围和小于±3%的带宽差.     

二维光子晶体耦合腔的多模双稳态光开关

利用时域有限差分数值模拟方法和耦合模理论分析方法，研究了Kerr型非线性二维光子晶体耦合腔结构中的光学双稳态开关。利用耦合模理论，分析了耦合腔结构的多模特性，以及对应本征态的局域强度分布特性，并讨论了在耦合腔结构中实现多模光学双稳态开关的原理。发现在二维耦合腔结构中，可以实现信号自泵浦和泵浦-信号两种类型的双稳态开关，且后者具有使泵浦和信号在频率和空间相分离的优点。利用非线性时域有限差分数值模拟方法，得到了高斯脉冲激励下的双稳态响应曲线。     

分布损耗在耦合腔行波管中的应用技术

本文就分布损耗在休斯结构耦合腔行波管中的应用技术进行了综述,着重介绍了分布损耗在其慢波电路中的布局技术。用分布损耗涂层有选择地涂复耦合腔行波管的匹配腔片和主腔片,将能有效地抑制行波管振荡,获得行波管高稳定的工作。     

Ka波段毫米波耦合腔慢波结构高频特性的实验研究

通过对Ka波段毫米波耦合腔慢波结构进行的实验研究,对比了在两种较典型的色散情况下所对应的高频特性的差异,并进一步探讨了耦合腔慢波结构在不同色散情况下所对应的高频特性的基本规律,最后还列举了进一步改进耦合腔慢波结构高频特性的有效途径,可以为今后的设计工作提供必要的参考。     

调谐微波滤波器的腔间耦合结构研究

本文详细地了调谐微波滤波器的腔间耦合结构对其调谐范围、通带宽度的影响。文中分析了圆孔耦合结构的特点，指出了其对调谐范围的限制以及传统公式存在的问题，提出腔间的矩形孔耦合结构，建立了侧面孔的等效电路模型，推导了矩形孔的设计公式。     

耦合腔行波管慢波结构的工作模式及其特性

耦合腔行波管慢波结构可工作于三种不同模式：正常模、简并模和反向模。应用改进的等效电路法计算了正常模腔通带和槽通带。求得的简并模耦合槽张角与实验值相符。最后讨论了反向模耦合腔行波管诱人的特点。     

Ka波段耦合腔行波管高频耦合系统的模拟

本文利用补偿片结构对耦合腔行波管高频耦合系统进行模拟,探讨了个基本参量的变化对整个系统匹配的影响。     

多腔径向耦合输出系统的等效电路分析

多腔径向耦合构成的输出系统具有多个频率点(离散状态)的宽带特性,该文从等效电路的观点出发,给出了多腔径向耦合输出系统的等效电路,根据Kirchhoff定律建立了矩阵方程,导出阻抗矩阵,解出其系统的谐振频率,鉴于它的多模特点抽出它的典型状态推导出它的模式结构,揭示了径向耦合双腔的模式分布,反对称于轴向耦合双腔(双间隙腔),它是由2--2模构成。     

三维螺旋慢波电路的精确的冷测模拟

利用MAFIA的准周期边界条件对螺旋慢波电路的高频特性进行模拟,发现模拟结果在一定的网格取值范围内作微小变化,在此基础上使得色散曲线趋于数值收敛;并提出利用MAFIA后处理模块直接计算耦合阻抗的方法;将模拟计算结果与实验测试值进行比较,其平均误差范围达到设计要求,为软件模拟的精确计算作了一些有益的研究.     

Validation of HFCS-I on Calculation of High-Frequency Parameters of Helical Slow-Wave Structures

To validate HFCS-I, a newly developed design tool for high frequency circuits of microwave tubes, the high-frequency parameters (including dispersion, interaction impedance and attenuation constant) of a typical helical slow-wave structure (SWS) for millimetre wave travelling-wave tube are calculated by HFCS-I and MAFIA. Both the direct calculation method and the Non-Resonant Perturbation (NRP) technique are adopted to get the interaction impedance. The obtained high-frequency parameters from HFCS-I and MAFIA are compared in detail and the consistency has proved the reliability and validity of HFCS-I.     

Tape Analysis of an Inhomogeneously-Loaded Helical Slow-Wave Structure for Broad-Band Traveling-Wave Tubes

Theoretical simulation of the dispersion and interaction impedance characteristics of an inhomogeneously-loaded helical slow-wave structure is validated. The structure is supported by double-curve-shaped rods which are smoothed out into a number of dielectric tubes with their respective effective permittivity values. The effects of the helix thickness are taken into account by considering a free-space gap equal to the difference between the mean helix radius and the outer helix radius. Moreover, the helix tape model is used instead of the simpler sheath-helix model. The theoretical predictions are compared with those of MAFIA simulation. The dispersion error is found to be within 3–6 percent and the impedance characteristic is in great agreement with that of MAFIA simulation. At last, for the sake of comparison, the cold-test characteristics under sheath-helix model are also provided.     

Three Dimension Simulation of Millimeter Wave Double Staggered Coupled Cavity Structure

After analyzed the cavity field mean method theory resolution, the software simulation method to obtain the resonance frequency, Q value and RF dispersion by MAFIA and ANSYS software is discussed for the double staggered coupled cavity Millitron structure in the millimeter-wave TWT. The resonance frequency and Q value of the single cavity is obtained and is consistent with two kind of the simulation software. Their average error is about 0.6%. The two kind of the simulation result is consistent to the design precise. The simulation method saves on the cost and time in the experiment, improve the data precise and work efficiency. The trend of the dispersion simulation result is consistent with the cavity field mean method theory result. The high end of the theory result is great contrast to that of MAFIA result. It shows that the theory adopt some hypothetical conditions, But the theory result has some instructional signification in initialization design of the novel slow wave structure.     

用MAFIA计算外观品质因数Q

应用电磁场计算软件MAFIA,采用反射相位法计算了速调管波导加载谐振腔的谐振频率和外观品质因数Q ext,其计算结果比较理想,误差在10%以内.     

基于MAFIA软件的螺旋线慢波结构冷特性仿真

利用MAFIA软件所提供的准周期边界条件,对两种不同夹持结构的螺旋线行波管一个周期结构的色散和耦合阻抗特性进行了仿真,并与国内开发的螺旋线行波管计算软件包的计算结果进行了比较,为今后进一步优化螺旋线行波管的慢波结构打下基础.     

Simulation of cold-test parameters and RF output power for acoupled-cavity traveling-wave tube

Procedures have been developed which enable the accurate computation of the cold-test (absence of an electron beam) parameters and RF output power for the slow-wave circuits of coupled-cavity traveling-wave tubes (TWT's). The cold-test parameters, which consist of RF phase shift per cavity, impedance, and attenuation, are computed with the three-dimensional electromagnetic simulation code MAFIA and compared to experimental data for an existing V-band (59-64 GHz) coupled-cavity TWT. When simulated in cylindrical coordinates, the absolute average differences from experiment are only 0.3% for phase shift and 2.4% for impedance. Using the cold-test parameters calculated with MAFIA as input, the NASA Coupled-Cavity TWT Code is used to simulate the saturated RF output power of the TWT across the V-band frequency range. Taking into account the output window and coupler loss, the agreement with experiment is very good from 60-64 GHz, with the average absolute percentage difference between simulated and measured power only 3.8%. This demonstrates that the saturated RF output power of a coupled cavity TWT can be accurately simulated using cold-test parameters determined with a three dimensional electromagnetic simulation code     

微带型曲折线慢波结构冷测特性的计算机仿真

在研究了微带型曲折线慢波结构色散特性、耦合阻抗等特性参数的分析方法基础上,利用电磁场仿真软件MAFIA和Microwave Studio对其进行模拟计算。对影响慢波电路特性的结构参数如微带宽度和微带厚度对其冷测特性的影响进行了仿真和分析,同时对介质杆支撑的曲折线慢波电路进行了分析。结果表明,微带宽度对其特性影响较为显著而微带厚度的改变影响不大,介质杆代替介质板使慢波电路的特性参数产生了较大的变化。     

优化极靴的微波炉磁控管磁场分析

利用MAFIA静态磁场仿真模块对微波炉磁控管磁路进行仿真分析，并通过对比实测结果改进模型，主要分析缩短极靴后的磁场变化，然后制作了样管，测试并比较性能参数，在保证输出功率和效率的前提下，达到节约成本的目的。     

W波段折叠波导慢波结构设计及三维注波互作用模拟

本文综合分析了折叠波导的几何尺寸和电子束参数，运用电磁场软件MAFIA的粒子模拟程序对三维折叠波导慢波结构进行了模拟．模型中，电磁波通过波导模式导入；为了克服较大空间电荷效应造成的电子注发散，使用了纵向聚焦磁场．基于三维互作用模型得到了W波段折叠波导的模拟结果，该结果可以对折叠波导慢波结构的三维互作用性能进行预测和分析．