X波段六腔渡越管振荡器的高频特性研究

 从麦克斯韦方程出发，采用时域有限差分法（FDTD）和离散傅里叶变换（DFFT）相结合的方法，通过数值计算得出了六腔开放式谐振腔中前四个谐振频率和场分布，计算出的谐振频率与实验测量结果基本相同。比较了开放腔和封闭腔谐振频率，验证了TEM波吸收边界条件，并在实际编程计算中得以应用。计算结果为六腔渡越管振荡器的机理研究提供了依据。     

利用场耦合理论研究开放微波谐振腔

在高功率微波(HPM)和驻波加速器的研究中，开放微波腔模式(微波场分布、频率和Q值)一直是大家所关心的问题，微波腔通常是具有复杂形状的圆柱腔；多年来，关于微波腔模式的研究一直在进行。从电磁理论(Maxwell方程)和有关的数学方法出发，建立开放微波腔模式同封闭微波腔模式之间的场耦合方程，由此确定开放微波腔模式。     

利用场耦合理论研究微波谐振腔

 根据Maxwell方程，微波腔中的实际微波场可以按微波腔的模式展开，从而确定微波腔的工作特性（如：工作频率、场分布等），但是实际微波腔的模式很难求解。从Maxwell方程出发，根据微波腔的具体边界，将微波腔分成：规则形状微波腔和非规则部分，建立实际微波腔模式同规则形状微波腔模式之间的场耦合方程，从而确定微波腔模式的频率和场分布。     

利用场分布计算单腔微波参量

介绍了利用加速管的场分布计算单腔微波参量的一种方法. 在已知耦合腔链各本征模式的谐振频率和电场分布的条件下，可以通过回路方程组求出耦合腔链的单腔频率和腔间耦合系数. 这种方法给加速管设计和调谐带来了很大帮助，在加速腔数目较多或者结构非均匀的条件下尤为有效.     

三腔渡越管振荡器高频结构的解析研究

 从圆柱坐标系下Borgnis位函数的齐次标量Helmholtz方程出发,引入慢波驻波概念及其场表达式,利用Borgnis位函数的边界条件及相邻子区公共界面上的场匹配条件,导出了三腔渡越管振荡器内角向均匀TM模的色散关系及场分布的解析表达式。运用该解析法求得三腔渡越管振荡器的谐振频率与实验中测得的微波频率一致,求得的场分布与数值法得到的场分布十分吻合。     

X波段五腔渡越管振荡器的理论与实验研究

提出了一种新结构的X波段五腔渡越管振荡器，进行了理论和实验研究。根据场分布进行了一维非线性分析，结果表明该结构可以产生高功率微波，并判断了工作模式，为TM01模的3π/5模。采用粒子模拟验证了一维非线性分析的结论，并优化设计出五腔渡越管振荡器,优化结果为:输出功率约1 GW， 工作频率9.3 GHz，束波转换效率约22%。实验中，通过参数调节，得到频率约9.25 GHz，峰值功率约780 MW，脉宽（半高宽）21 ns的输出微波，束波转换效率约为16%。实验结果与模拟结果基本符合。     

X波段五腔渡越管振荡器的理论与实验研究

 提出了一种新结构的X波段五腔渡越管振荡器，进行了理论和实验研究。根据场分布进行了一维非线性分析，结果表明该结构可以产生高功率微波，并判断了工作模式，为TM₀₁模的3π/5模。采用粒子模拟验证了一维非线性分析的结论，并优化设计出五腔渡越管振荡器,优化结果为：输出功率约1 GW， 工作频率9.3 GHz，束波转换效率约22%。实验中，通过参数调节，得到频率约9.25 GHz，峰值功率约780 MW，脉宽（半高宽）21 ns的输出微波，束波转换效率约为16%。实验结果与模拟结果基本符合。     

耦合孔对微波腔的影响研究

从Maxwell方程出发,将微波腔中的实际微波场按其本征模式展开,进行微波腔的工作特性(如工作频率、场分布等)的研究.在具体处理过程中,根据复杂结构微波腔的具体边界,将微波腔分成规则形状微波腔和非规则(含耦合孔)部分,建立实际微波腔模式同规则形状微波腔模式之间的场耦合方程,从而确定耦合孔对微波腔模式的影响,并对开耦合孔的圆柱腔进行了相应的理论和模拟研究. 关键词： 微波腔 模式 场耦合 圆柱微波腔     

C波段新型渡越管模拟研究

 在三腔渡越管的基础上设计了一种工作在C 波段的新型低阻轴向六腔渡越管，其阻抗为15 Ω左右，采用同轴输出。该器件采用大面积发射阴极，无须外加磁场，结构简单紧凑。采用2.5维PIC软件对该器件进行了2维数值模拟，在输入电压为483 kV、电流为32.5 kA的条件下，输出微波平均功率达到3.0 GW，主频为3.75 GHz，微波模式为TEM模。微波功率效率大于19%，比普通低阻抗器件有明显提高。     

两腔高功率微波振荡器研究

对一种新型两腔振荡器进行了理论和数字模拟研究.这种结构中的调制腔实现电子束速度调制，调制后的电子束在通过两腔之间一个微波场较弱的区间时实现电子束群聚，然后在换能腔实现电子能量到微波能量的转换，并通过输出结构输出.同时，调制腔和换能腔之间存在微波耦合，换能腔中的一部分微波能量可以耦合到调制腔，形成一个正反馈回路，在一定条件下实行微波振荡.设计了一个X波段的器件，理论效率为294%，25维Particle in Cell(PIC)程序模拟的效率为28%，微波频率为942GHz，微波输出功率为225GW. 关键词： 高功率微波 微波腔 模式 自洽方程     

一种S波段磁绝缘线振荡器的高频特性研究

 用数值计算的方法计算了S波段磁绝缘线振荡器（S-MILO）的主慢波结构谐振腔的π/4模、π/2模、3π/4模和π模的谐振频率，分别为1.40，2.21，2.46和2.51 GHz；计算出S-MILO封闭腔中的谐振频率依次为1.26，2.04，2.42和2.53 GHz，并计算了本征π模时的Q值。通过监测宽带激励源响应计算出S-MILO开放腔的谐振频率为2.43 GHz。对S-MILO开放腔传输特性研究表明：频率为2.25～3.05 GHz的微波，在第一腔内得到了有效抑制，输出微波的频率范围为2.2～2.5 GHz。通过对其传输特性进行研究，验证了S-MILO的高频电磁结构的合理设计。     

The new technique of harmonic power combination—Millimeter-wave quasi-optical harmonic power combination

In this paper, the new technique of harmonic power combination—millimeter -wave quasi-optical harmonic power combination is presented. In this technique, by compounding several closed resonators with a quasi-optical open resonator, the harmonic powers of active devices are combined, which takes effectively respective advantages of closed cavity power combination and open cavity power combination and improve the combination efficiency of multiple-device harmonic power combiner. The experimental results for W-band are given and shown this combination method is available.     

Cyclicity of laryngeal cavity resonance due to vocal fold vibration

Acoustic effects of the time-varying glottal area due to vocal fold vibration on the laryngeal cavity resonance were investigated based on vocal tract area functions and acoustic analysis. The laryngeal cavity consists of the vestibular and ventricular parts of the larynx, and gives rise to a regional acoustic resonance within the vocal tract, with this resonance imparting an extra formant to the vocal tract resonance pattern. Vocal tract transfer functions of the five Japanese vowels uttered by three male subjects were calculated under open- and closed-glottis conditions. The results revealed that the resonance appears at the frequency region from 3.0 to 3.7 kHz when the glottis is closed and disappears when it is open. Real spectra estimated from open- and closed-glottis periods of vowel sounds also showed the on-off pattern of the resonance within a pitch period. Furthermore, a time-domain acoustic analysis of vowels indicated that the resonance component could be observed as a pitch-synchronized rise-and-fall pattern of the bandpass amplitude. The cyclic nature of the resonance can be explained as the laryngeal cavity acting as a closed tube that generates the resonance during a closed-glottis period, but damps the resonance off during an open-glottis period.     

C波段磁绝缘线振荡器开放腔高频特性分析

 建立了C波段磁绝缘线振荡器开放腔模型，通过监测宽带激励源的响应计算出开放腔的谐振频率和有载品质因数。用时域有限差分法计算了不同的径向位置一个周期内的径向电场随纵向距离的变化。计算表明：0~4.1 cm区电场很小但不为零；4.1~11.5 cm区域电场呈现驻波特性；在11.5~20 cm区域电场分布比较复杂，表现两个性质，一是驻波场过渡到行波场，二是从周期性加载圆柱谐振腔的TM00模过渡到同轴线的TEM模；在20~36.85 cm区域电场每经过1/4周期向右传播1/4波长，表现出行波特性。由此根据该计算结果将开放腔中的场从左到右分成4个区：截止区、驻波区、过渡区和行波区。最后根据定义计算了开放腔的固有品质因数和有载品质因数。     

Control of the threshold intensity and hysteresis cycle of optical Bi(multi)stability via atomic injection and exit rates from cavity

The optical bistability (OB) and multistability (OM) in an open Λ-type three-level atomic system inside a ring cavity are investigated. It is found that the ratio of atomic injections β and the exit rates r ₀ from cavity evidently affects the threshold intensity of OB and OM. The effect of incoherent pumping field on the OB and OM of a medium is discussed. We show that the bistable behavior of the open system significantly differs from that in a corresponding closed system, especially with an increase in the incoherent pump rate. The intensity threshold is reduced in an open system but increases in a closed system. In addition, the dependence of OB and OM in an open system on spontaneously generated coherence, the relative phase the between probe and coupling fields, the coupling-field intensity, and the cooperation parameter are briefly discussed.     

Roles of Atomic Injection Rate and External Magnetic Field on Optical Properties of Elliptical Polarized Probe Light

In this paper we investigate the optical properties of an open four-level tripod atomic system driven by an elliptically polarized probe field in the presence of the external magnetic field and compare its properties with the corresponding closed system.Our result reveals that absorption,dispersion and group velocity of probe field can be manipulated by adjusting the phase difference between the two circularly polarized components of a single coherent field,magnetic field and cavity parameters i.e.the atomic exit rate from cavity and atomic injection rates.We show that the system can exhibit multiple electromagnetically induced transparency windows in the presence of the external magnetic field.The numerical result shows that the probe field in the open system can be amplified by appropriate choice of cavity parameters,while in the closed system with introduce appropriate phase difference between fields the probe field can be enhanced.Also it is shown that the group velocity of light pulse can be controlled by external magnetic field,relative phase of applied fields and cavity parameters.By changing the parameters the group velocity of light pulse changes from subluminal to superluminal light propagation and vice versa.     

相对论强流长脉冲速调管放大器

 为了研制高功率长脉冲速调管放大器,对其输入腔进行了3维粒子模拟研究。建立了S波段速调管放大器输入腔开放腔的3维模型,计算了开放腔的谐振频率和有载Q值。将束压束流从原来的600 kV,5.4 kA提高到837 kV,12.48 kA,实现了长脉冲100 ns的稳定运行,调制束流与实验结果一致。在结构不变的情况下,将束压束流提高到900 kV,16 kA时出现了模式竞争,只能稳定运行到50 ns。为了克服模式竞争,将耦合孔改为对称的双耦合孔后,输入腔系统可以稳定运行到100 ns。     

A Kerr cavity with a small rotation parameter embedded in Friedmann universes

The work of Einstein and Straus, in which they matched a spherical Schwarzschild cavity to an external Friedmann universe, has been extended to the case where the metric holding inside the cavity is that of Kerr, with a small rotation parameter. Families of solutions have been obtained for the exterior metric for the three cases of closed, open, and critically open universes. The exterior metrics are rotational perturbations of Friedmann-Robertson-Walker metrics and, in all of the cases, the conditions may be adjusted so that perturbations decay to zero as the spatial distance from the Kerr inhomogeneity increases.     

含腔电大尺寸导体目标电磁散射的一体化数值模拟

应用等效原理，通过引入口面上等效磁流将含腔导电目标电磁散射简化为腔内、外两个等效 问题. 腔内问题分段求解并应用级联法获得口面等效导纳矩阵；腔内外的耦合关系应用近似 边界元方法描述并由此获得口面等效磁流；最后，这一具有混合源的腔体内外一体化散射问 题则应用所提出的广义混合场积分方程方法建立电磁模型，并用多层快速多极子方法实现高 效数值求解. 实例计算结果与测试结果具有很好的一致性. 关键词： 含腔目标 电磁散射 混合场积分方程 数值分析