相匹配契伦可夫辐射式倍频

用波导产生倍频波时,如果倍频波进入辐射模区,仍然有相匹配问题。契伦可夫辐射式倍频不是自动地实现相匹配的。相匹配要求导波基波模式场,倍频传输场(自由波),倍频触发场,以及经多次反射透射后的辐射场的迭加形成的总辐射场处于同步的相匹配状态。根据这个相匹配的分析,提出波导契伦可夫相匹配的特有的方法,那就是对波导的模色散进行设计,并指出非对称波导的特有优点,是改变一个边界上的反射相变,即选择不同色散的线性材料作包层,由此可得到相匹配的高效契伦可夫倍频辐射。     

水基契伦科夫量能器单元的蒙特卡罗模拟

详细描述了作为中微子探测器的水基契伦科夫量能器单元的结构,并用GEANT4软件包对水箱单元契伦科夫光的光学过程做了仔细的蒙特卡罗模拟,结果显示水箱的设计是合理的,且此结果对探测器设计与优化具有重要意义.     

关于相对论闵可夫斯基时空中三角形不等式的倾向

给出了相对论闵可夫斯基时空中三角形不等式倒向的一个直接和初等证明方法。     

浅谈广义相对论的创立之四 闵可夫斯基四维时空的提出与应用

简述了闵可夫斯基"四维时空"概念提出的过程和"四维时空"的几何表示.介绍了玻恩应用他的几何分析方法和这一概念分析狭义相对论得出的几个有关时空观结论.     

关于相对论闵可夫斯基时空中三角形不等式的倒向

给出了相对论闵可夫斯基时空中三角形不等式倒向的一个直接和初等证明方法     

在速调管中空间电荷波对辐射波引起的电子束群聚的修正

 在相对论情况下,导出了速调管(klystron)和契伦柯夫(Cherenkov)器件中考虑空间电荷波影响的被调制电子束的谐波电流公式;并且分析了空间电荷波对电子束群聚的影响：在小信号时使群聚减小;在大信号时使群聚增强。     

用类比法推导爱因斯坦速度叠加公式

本文以狭义相对论的最简单的一维运动情形为例,分析了特殊洛伦兹变换在四维闵可夫斯基空间的表达形式及其转动意义,并结合类比法,推导了爱因斯坦速度叠加公式.     

等离子体填充0.14 THz相对论返波管模拟

模拟了0.14 THz相对论返波管中电子束与氩气相互作用产生等离子体的过程, 研究了在不同气压条件下, 等离子体对相对论返波管的输出功率、频率以及起振时间的影响. 模拟结果表明, 等离子体背景能引起太赫兹波段真空电子器件脉冲缩短, 并出现新的频率分量; 适当地注入等离子体能减少0.14 THz相对论返波管的起振时间, 提高器件的输出功率. 关键词： 太赫兹 相对论返波管 粒子模拟 等离子体     

填充等离子体的介质契伦柯夫脉塞

 利用自洽线性场理论，普遍讨论了电子在扰动场作用下的三维扰动，进而分别对薄环形相对论电子注和实心相对论电子注在填充等离子体的介质筒慢波波导中激励的契伦柯夫辐射进行了详细的分析，导出了其色散方程和波增长率。分析表明注波互作用是由于慢波系统中的波导模与电子注模耦合所致，填充等离子体后能大大提高注波互作用效率，并详细计算和分析了等离子体密度和电子注半径对波增长率的影响。     

相对论中的若干“勾股定理”

本文总结了作者讲授电动力学与狭义相对论的若干心得与体会;运用四维闵可夫斯基空间张量的性质及其缩并运算法则,介绍了用各阶四维张量构造相对论不变量即四维标量的方法,进而在所得四维标量为负定的类时标量时,推导出若干典型的勾股关系,并应用或验证于若干简单情形.     

Transition radiation,Cerenkov radiation and energy losses of relativistic charged particles traversing thin foils at oblique incidence

Semiclassical relativistic energy losses and the transition radiation are calculated for fast charged particles (e.g. electrons) traversing a thin dielectric foil at oblique incidence. The transition radiation formula is generalized for foils with spatial dispersion. This formula for oblique electron incidence is of particular interest for the observation of Cerenkov radiation, emitted from a dielectric foil. The emission of Cerenkov radiation is discussed for varying electron incidence angle and foil thickness by the aid of numerical computations.     

The Cerenkov Maser at Millimeter Wavelengths

The dispersion relation for the transverse magnetic modes (TMon,) of a partially filled, dielectric-lined, cylindrical waveguide driven by a cold relativistic electron beam is derived. The effect of a gap between the electron beam and the dielectric liner is included. The dispersion relation is then used to calculate the growth rate for the Cerenkov instability in the collective tenuous beam limit. Expressions are developed for the minimum current necessary for oscillation threshold and for the power output of the Cerenkov maser in the collective regime.     

圆波导契伦柯夫自由电子激光流体描述

用磁流体理论研究了契伦柯夫自由电子激光的性质,导出了空心束驱动的圆柱对称波导契伦柯夫自由电子激光的色散关系,利用色散关系计算了契伦柯夫不稳定性增长率,给出了饱和功率的估计值,考虑了束与介质间间隙对契伦柯夫自由电子激光的影响,并就空心束与实心束情况进行了比较。     

High-frequency emissions during the propagation of an electron beamin high-density plasma

A relativistic annular electron beam passing through a high-density plasma excites Langmuir waves via Cerenkov interaction. The Langmuir waves are backscattered off ions via nonlinear ion Landau damping. At moderately high amplitudes these waves are parametrically up-converted by the beam into high-frequency electromagnetic radiation, as observed in some recent experiments. A nonlocal theory of this process is developed in a cylindrical geometry. It is seen that the growth rate of the Langmuir wave scales as one-third the power of beam density. The growth rate of parametric instability scales as one-fourth the power of beam density and the square root of beam thickness     

X-ray Cerenkov radiation at grazing incidence of electrons

We have developed a theory of X-ray Cerenkov radiation for grazing incidence of relativistic electrons on a thin foil while taking into account absorption, reflection and refraction of radiation. The possibilities for the enhancement of radiation intensity are discussed on the basis of the theory developed.     

气体Cerenkov辐射的量子理论

本文采用量子场论的一级微扰论,建立了气体介质中Cerenkov辐射的量子理论,结果表明,它有与固体、液体Cerenkov辐射不同的特点:线状光谱且轮廓不对称和出现小的红移,辐射角与辐射频率无关,并随入射粒子速度的增大而减小,辐射对入射带电粒子的速度没有阈值限制,激发态与基态原子的Cerenkov辐射几率相等,理论结果与实验基本一致。 关键词：     

Intensity of radiation of charged particles passing through crystals

We have calculated the intensity of radiation of a relativistic charged particle moving in a crystalline medium, taking into account the interaction of the charge with the crystal as well as with the radiation. Various modifications to the usual Cerenkov radiation are discussed and under certain conditions enhancement occurs.     

Explosive instability in a backward wave oscillator

A plasma filled backward wave oscillator supports Trivelpiece-Gould (TG) and TM modes. The former can be driven unstable by a relativistic electron beam via Cerenkov interaction or by the plasma return current as two stream instability. This unstable TG mode can parametrically couple to a TM mode via a negative energy beam mode giving rise to an explosive instability     

Millimeter-Wave HF Relativistic Electron Oscillators

A review of the experimental study of single-mode oscillators based on stimulated bremsstrahlung and Cerenkov radiation of high-current relativistic electron beams is given. Three types of Cerenkov oscillators are investigated in detail: orotrons, surface wave oscillators and a flimatron (free electron maser (FEM) based on Smith-Purcell radiation). The bremsstrahlung oscillators studied are gyrotrons with TM modes, a ubitron operating at a quasi-critical frequency and cyclotron autoresonance masers. Electrodynamic and electron methods of mode selection provide stable radiation with a reproducible space structure of radiation in all oscillators under study. The radiation power attained 50-100 MW for long and 10-30 MW for short millimeter wavelengths at the efficiency up to 5-10 percent. Various types of oscillators are compared. Promising methods for increasing power and radiation frequency are discussed.     

圆波导契伦柯夫自由电子激光的单粒子理论

用单粒子理论研究了契伦柯夫自由电子激光的基本性质,给出了空心束圆柱衬介质波导契伦柯夫自由电子激光调谐特性,导出了增长率表达式,计算了克服谐振腔损失所需阈值电流和相互作用效率,讨论了束与介质间间隙的影响,并对空心束与实心束进行了比较,最后讨论了电子束品质对契伦柯夫自由电子激光的影响。