关于运动系统中电磁场的保持性问题的讨论

本文由连续介质中的可变场的矢量线的保持性条件，主要讨论了运动系统中电磁场的保持性问题。作为应用的例子，我们利用保持性条件加上狭义相对论的惯性系之间的变换公式，从另一个角度上导出了麦克斯韦方程。     

基于三维空间的无人机规避攻击导引设计

针对三维空间中无人机受到纯比例导引空空导弹攻击而采取机动规避的过程, 建立无人机与空空导弹的相对追逃运动模型。基于人工势场基本理论, 对空空导弹相对无人机的势力场进行分析, 构建指向无人机的势力场增加最快方向的态势模型, 利用反比例导引项结合反跟踪势场力项构成一种新的复合规避导引律, 分别对迎头攻击和尾追攻击时无人机规避攻击进行仿真。仿真结果表明, 该导引律能有效完成规避任务。     

电子在双曲函数摇摆场和轴向导引场中的运动分析

本文用扰动法来分析电子在具有双曲函数型摇摆场和轴向导引场中的离轴运动轨道和速度。发现了电子运动存在着丰富的回旋谐振频谱，有基波即磁共振和高次谐波回旋谐振和反回旋谐振，并且存在分数谐振和反谐振。     

BTT导弹增广比例导引律研究

比例导引规律相比于直接追踪法,跟踪精度有所提高,但是在目标机动性加大的情况下,传统比例导引规律制导精度仍不理想.因此,给出了三维空间导弹-目标追逃运动的空间矢量方程,建立了三维空间导弹-目标追逃运动模型,并基于李雅普诺夫稳定性理论,设计增广比例导引律(APNG).即在比例制导规律基础上,引入目标加速度补偿项来克服目标加速度对制导精度的影响.将该方法运用于机动目标的跟踪,仿真结果表明了增广比例导引律相比于传统比例导引律,制导精度高,脱靶量低,制导飞行时间短,制导性能有极大的提高.     

雷达抗反辐射导弹诱饵布阵仿真研究

在建立一套坐标系的基础上,给出了测向系统在雷达和诱饵合成场中的导引信号形成模型.引入了反辐射导弹运动模型,确立了雷达诱饵对抗反辐射导弹的物理和数学模型,并获得了解决相应物理问题的基本公式.文中利用数值模拟的方法分析了雷达和诱饵布阵对诱偏效果的影响.数值计算表明,通过诱饵布阵可以有效地对抗反辐射导弹.     

耦合双腔回旋管的束波互作用分析

本文导出了回旋管中电子与高频场同步互作用方程的普遍形式,考虑了导引中心漂移和场分布相位变化的影响,利用一个双腔回旋管模型,通过调节场分布f(z),计算了TE021模二次谐波单模工作时的互作用效率。计算表明,对=1.5,效率可高达53％。我们还讨论了双腔结构的特点;对单、双腔电子群聚过程进行了比较;分析了导引中心漂移和场分布相位对互作用的影响。     

带轴向导引场激光泵浦FEL的辐射机制分析

本文从单粒子理论出发，计论分析了相对论电子束同时处于激光泵浦场，轴向导引磁场以及自身辐射场中的运动和辐射过程；结合对辐射波增益的计算，发现这种电磁波泵浦自由电子激光与一般静磁泵浦场中的波粒相互作用以及辐射机制类似，可以从不同角来加以解释。通过分析计算结果；本文展现了清晰的物理图象。     

增益导引折射率反导引光纤激光特性的研究

为了实现大模场单模光纤,采用增益导引和折射率反导引相结合的新方法,进行了腔镜反射率对增益导引折射率反导引光纤激光器影响的理论研究,数值模拟了不同增益系数和负折射率差值情况下的模场分布及对模场的影响,得出了单模运转条件。结果表明,增益导引和折射率反导引光纤可以实现大模场面积,这为设计大模场光纤提供了理论依据,具有重要的指导意义。     

高斯反射率方形平凹腔激光模场的有限元分析

利用柯林斯公式和边界有限元方法，将方形球面镜腔的衍射积分方程转化为矩阵方程，并对高斯反射率方形平凹腔的模场分布进行了数值计算。研究结果表明，高斯反射率方形平凹腔具有较好的选模性能，可以应用于高功率激光器以获得高质量的激光光束。     

新型长脉冲超高效放大器Magnicon研究

文章简述了Ｍａｇｎｉｃｏｎ磁旋管的来源和发展过程，概述了它的原理。磁旋管放大器使用直圆柱谐振腔。本文从腔内旋转ＴＭ（ｎ１０）场的表达式出发，给出了谐振腔的欧姆损耗功率、冷Ｑ等的计算公式。它与现有的静态ＴＭ（ｎ１０）模场的相应公式不同，而后者目前仍被用于磁旋管的设计。文章从电子动力学方程出发，求得无源磁偏转腔的电子速度和位置解（位置与现有的不同），求得偏转腔中电子束与波的相互作用瞬时功率解。文中还给出输出腔柱坐标系的能量动力学方程，输出腔末端参数公式的相对论修正系数，以补充现有的非相对论公式。     

Simplified small signal gain calculations in free electron lasers

A method proposed recently is used for the evaluation of the small signal gain in various free electron laser configurations. The theory is applied to (a) the wigglerfree free electron laser with a uniform axial guide magnetic field and arbitrary direction of propagation of the amplified radiation and (b) the free electron laser with the axially modulated guide field (lowbitron). It is demonstrated that the new approach simplifies the gain calculation significantly in comparison with the traditional method.     

Equations of motion for a free-electron laser with an electromagnetic pump field and an axial electrostatic field

The equations of motion for a free-electron laser (FEL) with an electromagnetic pump field and a static axial electric field are derived using a Hamiltonian formalism. Equations governing the energy transfer between the electron beam and each of the electromagnetic fields are given, and the phase shift for each of the electromagnetic fields is derived from a linearized Maxwell wave equation. The relation between the static axial electric field and the resonant phase is given. Laser gain and the fraction of the electron energy converted to photon energy are determined using a simplified resonant particle model. These results are compared to those of a more exact particle simulation code.     

Analysis of a large-orbit gyrotron in a coaxial waveguide underassistant background fields

The dispersion relation of a large-orbit gyrotron in a coaxial waveguide excited in the transverse-electric mode was developed starting from the beam-present wave equation. The relativistic Vlasov's equation was solved under tenuous beam approximations for the perturbed electron distribution function, hence the required current density to be used in the wave equation was found. The analysis was generalized, with respect to background fields, by considering a dc radial electric field and a dc azimuthal magnetic field, over and above conventional dc axial magnetic field. The dispersion relation was solved for the complex frequency for a given propagation constant and the imaginary part interpreted for the growth rate as well as the saturated efficiency of the device. Similarly, for a given frequency the dispersion relation was solved for the complex propagation constant and the imaginary part interpreted for the gain of the device, if configured as an amplifier. Two peaks were obtained in the gain-frequency response corresponding to two points of intersection between the beam-mode dispersion line and the waveguide-mode dispersion curve. The improvement in the growth rate, gain and saturated efficiency was predicted by the application of the additional background fields. A redistribution of beam kinetic energy between the axial and transverse electron velocities led to a remarkable enhanced saturated efficiency at the second peak. A detailed study of the variation of device performance with respect to the gain and saturated efficiency was presented, for a wide range of the dc background field and electron kinetic energy distribution parameters     

Analysis and nonlinear simulation of a quadrupole wiggler FEL atmillimeter wavelengths

The use of a helical quadrupole wiggler field in a circular guide for amplification of millimeter waves is discussed. The effects of space charge and axial field are considered for beam stability for near-axis orbits. When space charge is neglected, the orbit equations and properties and characteristic betatron oscillation of frequencies are examined by a linearization of the orbit equations. A nonlinear simulation code for dipole wigglers is modified to examine optimum gain TE₂₁ waveguide modes for a quadrupole wiggler in the 30-300 GHz range     

A self-consistent two-dimensional model of quantum-wellsemiconductor lasers: optimization of a GRIN-SCH SQW laserstructure

A two-dimensional model for quantum-well lasers that solves, self-consistently, the semiconductor equations together with the complex scalar wave equation is described. It incorporates a position- and wavelength-dependent gain function which is derived from a quantum mechanical calculation. Such a model enables one to predict the characteristics of a quantum-well laser with a minimal number of empirical parameters. The output of the model includes light-current characteristics, the current distribution, and the optical field intensity distribution, obtained simultaneously in the calculation. Examples for modeling GRIN-SCH SQW (graded-index separate confinement heterostructure single quantum well) ridge wave guide lasers are given, and good agreement with experimental results is obtained. The model is used to optimize the geometry of a GRIN-SCH SQW laser for minimum threshold current and maximum efficiency     

梯度周期场自由电子激光器

本文在单电子模型的基础上逐阶求解相对论电子的洛伦兹方程和能量方程,得到了梯度周期场自由电子激光器的增益表达式.计算表明当周期磁场的振幅沿z方向变化时,增益可获得提高.     

Dispersion and gain investigation of a Cerenkov grating amplifier

The sheet electron beam propagation over a rectangular deep groove grating is investigated and the interaction between surface harmonic waves, which are evanescent above the grating surface, with a dilute sheet electron beam is analyzed. It is assumed that a strong axial magnetic field is applied to constrain the motion of electrons along the waveguide axis. Under these conditions, a complex dispersion equation is derived and analyzed by using Taylor expansion. This expansion results in an analytical formulation for the gain. Using the derived analytical formulation of the gain, the effects of beam thickness, beam-grating gap, and characteristics of grating on gain is investigated.     

The dispersion equation for the gyrotron amplifier

The dispersion equation For the gyrotron amplifier has been derived by uso of a general expression for the perturbed propagation constant of a waveguide containing r.f. current. The derivation is valid for all guide modes and cyclotron harmonica and shown that space–charge dose not affect TE^° _on modes. The distribution of the unmodulated beam can be simply expressed as a function of the coordinates of guiding centres, showing that power transfer can occur' through radial drift of electrons' orbits. For a univeloeily beam, growing–wave gain is found over a bandwidth of about 20%, but the same bandwidth is unlikely to be obtained with a quasi–max–wcllian beam unless the spread in axial momentum lies within stringent limits.     

An integral equation and its application to spiral antennas onsemi-infinite dielectric materials

This paper presents an integral equation that can handle wire antennas on a semi-infinite dielectric material. The integral equation is reduced to a set of linear equations by the method of moments. For efficiency, the impedance matrix element Z_m,n is divided into two parts on the basis of weighted Green's function extractions. The far-zone radiation field, which is formulated using the stationary phase method, is also described. After the validity of the presented numerical techniques is checked using a bow-tie antenna, a spiral antenna is analyzed. The current distribution, radiation pattern, axial ratio, power gain, and input impedance are discussed. It is found that the radiation field inside a dielectric material is circularly polarized. As the relative permittivity of the dielectric material increases, the angle coverage over which the axial ratio is less than 3 dB becomes narrower     

带轴向场自由电子激光器的增益

给出了带轴向场自由电子激光器的增益,并讨论了轴向场的效应。