介质切伦柯夫脉塞的粒子模拟

通过对介质切伦柯夫脉塞的分析,推导出了注波互作用色散方程,由色散方程得出了色散曲线,并且对介质膜片加载的切伦柯夫脉塞进行了数值模拟。研究发现微波频率随着介质膜片内外半径比值的变化而变化,通过调整介质膜片的厚度来调整输出频率,从而使研制出高频率微波器件成为可能。     

波纹波导加载等离子体后注波互作用的线性理论

本文综合考虑了系统存在的离子通道和电子束传输的脉动性能,导得了小信号下等离子体加载波纹波导的色散方程,并具体讨论了高频系统的色散特性,研究了电磁波增长率与等离子体密度间的关系.由于考虑了电子束注入后系统的变化,这种处理方法将更加符合微波器件的实际情况.     

Practical Dielectric Filled Waveguide

This paper describes the development of a laminated teflon-filled dielectric waveguide using techniques similar to what has been done in the flexible coaxial line. It describes the development of dielectric waveguide giving the theoretical design of the teflon-filled dielectric waveguide from both a mechanical and electrical point of view.     

Characteristics of Metallic Waveguides Inhomogeneously Filled with Dielectric Materials with Surface Plasma Layers

The propagation of millimeter waves in metallic waveguides inhomogeneously filled with dielectric materials having surface plasma layers is characterized. The modal phase shift and attenuation of a 94-GHz wave are computed for a 10-µm plasma layer thickness as a function of carrier density. In the unexcited state, 90 percent of the millimeter-wave power is confined to the interior air region of the guide, while the remaining 10 percent propagates in the semiconductor insert. In the excited state at high injection levels, over 99 percent of the wave power propagates in the air region. Consequently, in this state, the waveguide will have a very low loss. A resonant cavity using the waveguide configuration shown to have a wide tuning range and high cavity Q.     

Linear Theory of Plasma-Filled Coaxial Cylindrical Cherenkov Maser

Injection of background plasma into the beam-wave interaction region can greatly enhance the beam-wave interaction efficiency and the microwave output power of the device. In this paper, a new type of plasma-filled slow-wave structure, i.e., plasma-filled, dielectric-loaded coaxial cylindrical waveguide with a dielectric ring enclosing tightly the inner conductor, is developed. The Cherenkov radiation excited by the beam-wave interaction in the slow-wave structure is examined by use of the self-consistent linear field theory. The dispersion equation and the synchronized condition of the beam-wave interaction are derived. It's clearly shown that the Cherenkov radiation excited by the beam-wave interaction results from the coupling between the slow electromagnetic wave, TM-modes, propagated along the slow-wave structure and the negative-energy space-charge wave propagated along the relativistic electron beam. And the wave growth rate is solved, and the beam-wave energy exchange in the presence of the background plasma is discussed. Finally, the effects of the background plasma density on the dispersion characteristics, the distribution of the longitudinal fluctuating electric field, the wave growth rate and the beam-wave energy exchange are calculated and discussed.     

环形相对论电子注激励的等离子体介质切伦可夫脉塞

利用自洽线性场理论，考虑电子的三维扰动，分析了环形相对论电子注在填充背景等离子体的介质筒慢波波导产生的切伦可夫辐射，其环形电子注对主波互作用的作用完全要用一跳变条件来描述，导出了其色散方程和波波互作用的同步条件，求得了是子注产生的波增长率，分析了背景等离子体密度和电子注半径对波增长率的影响。     

Linear Study of a Large-orbit Coaxial-waveguide Cyclotron Autoresonance Maser Amplifier

A linear theory based on Maxwell-Vlasov equations and the Laplace transform is presented to describe the large-orbit coaxial-waveguide cyclotron autoresonance maser (CARM) amplifier. A 35-GHz, TE_5,1-mode large-orbit coaxial-waveguide CARM amplifier is specifically analyzed. Good agreement between the linear theory and the nonlinear simulations is found in the exponentially growing region of the wave. Results show that the operating magnetic field and the electron-beam energy and average radius substantially affect the power, and especially, a small beam current may be unsuitable to a large-orbit CARM amplifier operation.     

等离子填充扩展互作用振荡器研究

对等离子体填充扩展互作用振荡器进行了研究,通过CST软件研究了填充不同密度等离子体对Ka波段矩形耦合腔扩展互作用振荡器高频特性的影响,得到了通过改变等离子体密度与工作电压实现调节扩展互作用振荡器工作频率的方案.利用CST粒子工作室对其进行了粒子模拟分析,结果表明通过电子束电压和等离子体密度的共同调节,可使Ka波段扩展互作用振荡器实现34.14～37.99 GHz的调谐.     

Analysis of Stripline Filled with a Multilayered Dielectric Medium

An analysis has been carried out using conformal transformation for the case of a symmetric stripline filled with multilayered discrete dielectric media with their interfaces parallel to the ground planes. This has been applied to a stripline structure filled with a medium having a relative dielectric constant which is continuously varying in a direction perpendicular to the ground planes. Eight different distributions, such as Gaussian, parabolic, and semicircular, are considered for this variation of relative dielectric constant. Impedance data on stripline are preseuted for all these cases. The results of limiting cases obtained from this general formulation are compared with those existing in the literature.     

Study of Disk-Loaded Waveguide Filled with Plasma

Recently disk-loaded waveguide has been widely used in high-power traveling wave tubes (HPTWT). It has been shown in many experiments that the interaction efficiency and output power can be increased greatly by injecting plasma into the vacuum microwave device. Using field analysis, the dispersion characteristics and the interaction impedance of the disk-loaded waveguide filled with plasma are analyzed in a strong longitudinal magnetic field. In conclusion, the frequency of the TM₀₁ mode increases as the density of the plasma increases. It also can be found when the plasma density increases to a large scale, the TM₀₁ mode of the disk-loaded waveguide overlaps the TG mode, these two modes couple each other and form the new hybrid modes.     

The Linear and Self-Consistent Nonlinear Theory of the Electron Cyclotron Maser Instability

In this paper the linear and nonlinear theory of the electron cyclotron maser instability is considered. The configuration used to study the maser instability consists of relativistic electrons gyrating about and drifting along a uniform magnetic field within a parallel plate waveguide. Relativistic effects associated with the gyrating electrons are responsible for excitation of the transverse electric mode in the waveguide. Linear theory shows that the growth rate maximizes when the axial beam velocity coincides with the axial wave group velocity of the excited electromagnetic wave. This allows us to perform the nonlinear analysis in a frame where both the axial wave number and axial beam velocity vanish. We have found that the maser instability exists only if the perpendicular beam energy exceeds a threshold value. Our analysis also describes the temporal nonlinear evolution of the field amplitude and frequency of a single excited wave. The nonlinear wave dynamics are self-consistently determined from the nonlinear particle orbits through the force and wave equations. The nonlinear analysis shows that there are two possible mechanisms for the saturation of the unstable wave: 1) depletion of the available free energy associated with the rotating particles and 2) phase trapping of the gyrating electrons in the wave. The initial beam parameters determine which of the two mechanisms is responsible for saturation. Competition between the two saturation mechanisms leads to a peaking in the energy conversion efficiency as a function of beam energy. Numerical results of the nonlinear formalism show that energy conversion efficiencies from the particles to the wave can be as high as 60 percent in the beam frame. Furthermore, by appropriately contouring the external magnetic field, among other things, efficiencies as high as 70 percent can be realized.     

Linear Theory of the Beam-Wave Interaction in the Arbitrary Cylindrical Cerenkov Device

The “hot” dispersion equation in Cerenkov devices has been derived and analyzed numerically using the self-consistent linear theory. In principle, the linear analysis can be applied to efficiently calculating all kinds of beam-wave interaction in various Cerenkov devices composed of axisymmetric slow-wave structures (SWS) with arbitrary periodic profile. Then the results for Cerenkov devices with three typical SWS profiles are presented.     

A Simple Model for the Line Parameters of a Lossy Coaxial Cable Filled With a Nondispersive Dielectric

This paper discusses a simple model for approximating the per-unit-length parameters of a lossy cable providing a smooth transition from low to high frequencies. Using Schelkunoff's classical expressions for the transmission-line parameters of a coaxial line, the simple model is postulated and used to provide approximate responses that can be compared with the rigorous solutions. This approximate model is shown to be accurate and offers an alternative to evaluating the Bessel function expressions for the line parameters     

Propagation in Rectangular Waveguide Filled with Skew Uniaxial Dielectric

A solution is given for propagation in rectangular waveguide fully loaded with a uniaxial dielectric, with the C-axis lying anywhere in the transverse plane. This problem arises in the design of particular traveling-wave masers. By application of the Rayleigh-Ritz method to Berk's variational expression, the problem is reduced to a matrix eigenvalue problem, and in a form suitable for direct evaluation on a digital computer. An explicit approximate solution is, however, shown to give accurate results. The analysis can be interpreted directly in terms of mode coupling of the usual rectangular waveguide modes, and the possible extension is indicated to general tensor media and to circular or elliptical waveguide.     

Discontinuities in a Rectangular Waveguide Partially Filled with Dielectric

The modal spectrum for a rectangular waveguide with a dielectric slab at the bottom of the guide is obtained following the Characteristic Green's Function method developed by Marcuvitz. Then a four-terminal network is found as equivalent to the junction of the partially filled waveguide and an empty rectangular waveguide. An integral equation is written for the electric field at the plane of the junction and variational expressions are derived for the parameters of the four-terminal network connecting the transmission line equivalent to the partially filled waveguide to the transmission line equivalent to the empty guide. A reasonable guess for the electric field at the discontinuity gives approximate values for the parameters of the four-terminal network. These values agree with experiment. The parameters of the network are plotted vs frequency and thickness of the slab.     

Coupling of NRD-Guide Filled with Low Permittivity Dielectric Between Waveguides

A new version of NRD-guide coupling structure is proposed in which a low permittivity dielectric is filled between the coupling waveguides. It takes full advantage of the common NRD-guide with more flexibility. The choice of different dielectric materials can optimize the required performance. The corresponding coupling characteristics are analyzed. Some examples are given to show the new coupling characteristics. An important feature is the enhanced coupling between the waveguides and increased attenuation in the transverse direction, and this implies a size reduction and enhanced EMC capability. Furthermore, the filling of the low dielectric material between the coupling waveguides makes the structure an integrated unit and especially suitable for realization by micro-electromechanical system (MEMS) or by microwave integrated circuits.     

填充电各向异性媒质的矩形波导的研究

导出了在直角坐标系中电各向异性媒质中的波动方程，并在单轴晶体填充的矩形波导中进行了求解，研究了场的特性，找出了一些规律性的结论。     

Propagation in a Waveguide Partially Filled with Anisotropic Dielectric Material

A rectangular waveguide partially filled with an anisotropic dielectric material has been studied. The method of analysis has been shown to be quite powerful. A new configuration with a rectangular waveguide unsymmetrically loaded with a rectangular dielectric insert has been analyzed, tested experimentally. The special effects of mode coupling by breaking the symmetry of the structure are studied and the consequences for single-mode operation with application to masers in the millimeter-wave region are demonstrated.     

部分介质填充槽波导色散特性的网络分析

本文给出了部分介质填充单槽和非对称双槽波导的横向等效网络。以此为基础,用微波网络方法分析了各种槽波导的色散特性,并将所得到的数据与用其它方法得到的结果进行比较,两者吻合好。证实本方法在保持有高的计算精度的情况下极大地简化了分析和求解过程。文中通过对宽带槽波导定向耦合器的具体设计,证明了本方法在槽波导电路分析和设计中的重要实际意义。     

Mode Theory of Waveguide Filled with Warm Uniaxial Plasma

Characteristics of wave propagation in a guide filled with uniaxial anisotropic warm plasma are investigated. Basic equations of the plasma are derived. The validity of the plasma model and its physical significance are discussed. It has been found that TE modes are not affected by the presence of plasma. However, TM modes do have significant changes. Under the condition specified, each TM mode splits into two submodes. One has a low-frequency cutoff and the other propagates for all frequencies. The nature of power transfer in these modes is also investigated. A comparison of the effects as well as the physical significance of the changes due to cold and warm uniaxial plasma models are discussed.