地面附近的高空核爆电磁脉冲环境

 主要研究在高空核爆的双指数类型电磁脉冲平面波入射时，地面附近的电磁脉冲环境。计算给出了在不同入射波状态，不同地表介质电气特性和距地面不同高度等条件下的电磁脉冲环境参数，归纳了一些规律性认识。结果显示：地面附近的电场会随距地面高度的不同而发生显著的变化，对于水平场分量，其反射场总是试图抵消入射场，而对于垂直场分量，其反射场叠加在入射场上，使得地面附近的垂直场强幅值一般大于入射波场强幅值；当入射波仰角增大时，合成电场波形的脉冲宽度会变宽；地表介质的电气特性参数不同也会对地面附近电场的波形和幅值造成一定的影响。     

地面附近架高线缆HEMP响应计算的Agrawal和Taylor模型比较

研究在高空核爆电磁脉冲(HEMP)的作用下,地面附近架高线缆感应瞬态电压、电流的传输线模型计算方法并进行比较。考虑到有耗地面的电气参数,列举了Agrawal和Taylor两种传输线理论模型的异同,应用格林函数求积分和叠加定理,分别采用两种模型,计算并比较了不同入射波和线缆布放状态下的电压、电流响应,以及各场分量(水平电场、垂直电场和水平磁场)单独存在时对电流、电压响应的贡献。结果显示,Agrawal和Taylor模型得到的电压、电流响应是一致的,可以考虑在有界波电磁脉冲模拟器中进行短线缆的效应实验;由于相同的场分量在不同的模型中对电压、电流响应的贡献并不相同,因此在阐述某一场分量对线缆响应贡献大小时,应该首先说明所采用的传输线模型。     

电磁脉冲辐射器近区场数值模拟

 电磁脉冲辐射器是便携式电磁脉冲电场屏蔽效能测试设备的关键部分。提出了一套小型电磁脉冲辐射器的方案，并采用时域有限差分法在计算机上模拟了辐射器产生的近区电磁场, 结果表明，如果高压脉冲源产生的脉冲电压为双指数波，则通过天线辐射产生的近区场的波形也为双指数波，从而，使近场参数均能达到测试设备所要求的指标，说明所提供电磁脉冲辐射器的方案为可行。     

电磁脉冲模拟器电磁场计算

 利用电磁场张量法计算了平行板电磁脉冲模拟器内的电磁场并推导了其时域解析表达式。按照模拟器的平行板段和前后三角板的结构将平板近似为线网格。场的幅值由各线段元的不同滞后时间叠加来确定,其方向由线段元和场点的单位矢量经简单矢量运算来确定。计算结果表明：平行板段内的场具有横电磁分布特性,而靠近三角板处由于各线段元的非对称性贡献将使场出现其它分量。通过对模拟器的电场测量值与理论计算值相比较可知,两者大致相同。     

水平极化电磁脉冲模拟器空间场的数值模拟

 采用时域有限差分方法，对水平极化电磁脉冲模拟器所产生的电磁场进行数值模拟，在时域中计算了电磁场的时间 空间分布。讨论了电磁脉冲模拟器产生的电磁脉冲波形和场的空间变化、均匀性等重要因素。结果表明，模拟器产生的电磁脉冲前沿为10ns，接近脉冲电压前沿，波形与脉冲电压波形（双指数波）相差较大；峰值场强在对称轴上并非与距离成反比，而是随距离增大而迅速减弱；该模拟器的双锥 笼形天线能在大范围内（大于等于50m,水平方向）产生均匀分布、高峰值场强、快前沿的电磁脉冲。     

水平极化有界波电磁脉冲模拟器仿真与实验研究

结合传统有界波模拟器和辐射波模拟器的特点,采用新型双锥-线栅型平板天线结构,设计了一台水平极化有界波电磁脉冲模拟器。通过电磁仿真和实验测试,对模拟器的辐射特性和场均匀性进行了研究。仿真结果和实测结果基本一致。结果表明,模拟器能产生包含地面反射的水平极化电磁脉冲环境,波形满足上升沿(2.5±0.5) ns、半高宽(23±5) ns的高空电磁脉冲标准要求。模拟器使用灵活机动,能在不小于5 m×3 m×2 m工作空间内产生峰值场强不小于50 kV/m的6 dB均匀场,也能在降低测试场强时提供更大的工作空间。     

辐射波电磁脉冲模拟器笼形天线辐射特性的并行计算

 考虑到辐射波电磁脉冲模拟器笼形天线尺寸过大、在单个微机上计算其辐射特性的时间过长及内存受限制,使用基于消息传递接口（MPI）平台的用于同轴线馈电的时域有限差分并行算法,并结合天线理论模拟分析了同轴线馈电的辐射波电磁脉冲模拟器双锥笼形天线在双指数脉冲电压激励下的脉冲辐射特性。并行时域有限差分计算时,整个时域有限差分计算区域的网格总数约为20亿。由计算结果分析可知：当锥半径大于3.5 m后,笼形天线的半径大小对电场的上升沿和峰值的影响不大;对地面上方0.5 m处的几个测试时,其上升沿、半高宽及脉冲峰值受地面反射及地面损耗的影响比较大,而对于地面上方6 m处的几个测试点,除半高宽外,几个测试点的辐射场脉冲峰值及上升沿受地面影响较小;离地面越近的点,峰值减小得越快。     

冲击脉冲辐射天线辐射场计算及应用

根据由张量法得到的任意线天线电场计算公式,利用镜像法推导,得到冲击脉冲辐射天线辐射电场的时域解析表达式。应用该表达式计算冲击脉冲辐射天线应用于辐射波电磁脉冲模拟器的时域辐射场,并与数值计算进行比较,结果表明:解析计算得到的辐射场波形与数值计算结果吻合较好,因此,利用解析表达式可以方便地观察天线结构参数对天线辐射场波形的影响,从而选取合适的参数以产生符合标准要求的天线场波形。     

离散电阻加载的大型垂直极化EMP辐射波模拟器的并行FDTD模拟

将电阻设置为跨网格有耗介质，进行离散电阻加载的大型垂直极化电磁脉冲（EMP）辐射波模拟器时域场的并行FDTD模拟.给出不同离散电阻加载方式下模拟器辐射场的时域波形，分析离散电阻加载对模拟器辐射场的影响，并给出离散电阻加载的模拟器有圆筒效应物时的时域波形.结果表明：电阻加载能有效减小模拟器顶端的电流反射，从而改善辐射场的时域波形，但电阻加载也可能会导致模拟器辐射性能的降低；当效应物开孔所在的侧面靠近模拟器且与模拟器极化方向平行时耦合进入圆筒内的电磁波能量较多.计算方法具有通用性，可用于进行离散电阻加载的其它大型垂直极化EMP辐射波模拟器时域场的模拟，包括导电地面存在且有效应物存在时的时域耦合场的模拟.     

椭圆弧型过渡段有界波模拟器

提出并设计制作了一种椭圆弧型过渡段有界波电磁脉冲模拟器,并与锥形平板过渡段有界波模拟器进行了对比。采用仿真和试验两种方法,仿真在电磁场仿真软件CST中开展,试验实际测量得到前沿上升时间约2 ns、脉宽约25 ns的双指数电场波形和前沿上升时间约2 ns、平顶持续约80 ns的阶跃型电场波形。仿真和试验结果表明:该模拟器有效削弱了前后过渡段与平行板段连接处的不连续性对场波形的影响。     

Optimum coupling and efficiency of dye lasers

Evanescent waves and fields play an important role in microwaves, quantum mechanics, optics and elastic waves. Because electromagnetic waves in waveguides have dispersion characteristics similar to those of a unidimensional de Broglie wave, there is a close analogy between quantum mechanical tunneling and the transition through an attenuating sector of a waveguide. Microwave “evanescent mode” filters, quantummechanical tunneling resonance and optical frustrated total internal reflection filters are compared in light of this analogy. The flowgraph technique and “unit real” function representation are shown to be effective in discussing the interdependence of incident and reflected waves in various locations in multilayered structures. In electrognetic and elastic waves, the role of evanescent waves is significant in the case of incident beams of limited extent. The role of equivalent circuits of transverse resonance is discussed in the context of oscillatory natural modes determining the character of propagating fields.     

Acoustic X-wave reflection and transmission at a planar interface: spectral analysis

The spectral structure of a three-dimensional X-wave pulse incident on a planar surface of discontinuity is examined. Introducing a novel superposition of azimuthally dependent pulsed plane waves, it is shown for oblique incidence that the reflected pulse has a localized wave structure. On the other hand, the transmitted field maintains its localization up to a certain distance from the interface, beyond which it starts disintegrating. An estimate of the localization range of the transmitted pulse is established; also, the parameters affecting the localization range are identified. The reflected and transmitted fields are deduced for X-waves incident from either a slower medium or a faster one. For the former case the evanescent fields in the second medium are calculated and their explicit time dependence is deduced for a normally incident X-wave. Furthermore, at near-critical incidence the transmitted pulse exhibits significant pulse compression and focusing.     

平面电磁波在任意方向运动的介质-介质界面上的反射和透射

研究平面电磁波从一种介质入射到另一种以任意方向运动的介质时,在介质界面上发生的反射和透射现象,从Maxwell方程组、运动界面的边值关系和运动介质的本构关系出发,得到了反射波和透射波电磁场矢量与入射波电磁场矢量的关系的表达式、反射和透射系数,讨论了反射波、透射波与入射波之间的能量关系,电磁波对运动介质作用力的性质,并得出一些新的结论． 关键词：     

基于TEM喇叭的辐射波模拟器天线的近场特性

 给出一种新型核电磁脉冲辐射波模拟器天线，并用时域有限差分方法分析和优化天线的结构。天线的激励源是由同轴线馈入的强电压脉冲。优化了平行板传输线和TEM喇叭的尺寸，并对天线的近场进行分析，给出了天线尺寸对近场特性的影响。数值模拟结果表明，在距离天线口径100m处的电场强度可达20kV/m。     

New Effect for Detecting Gravitational Waves by Amplification with Electromagnetic Radiation

The perturbation of Dirac particles moving in a constant magnetic field is calculated for simultaneously incident parallel monochromatic circular polarized electromagnetic and gravitational waves. Resonances are found which depend on the initial energy of the charged particles, the magnetic field, and the frequencies of the incident waves. A suited choice of these parameters allows the selection of only one resonance that is proportional to the product of the squares of the amplitudes of both waves. This effect is valid for all bound systems of Dirac particles interacting simultaneously with electromagnetic and gravitational waves. At least in principle this resonance effect can be used to detect the gravitational waves in the lab. For regions of the universe with strong electromagnetic and gravitational waves and suited magnetic fields this effect may play another important part for the acceleration of charged particles.     

Pulse transmission through an interface between linear and resonance media

The problem of transmission of an optical pulse through an interface between linear and resonance media is addressed. Parameters of the transmitted and reflected waves versus the parameters of the incident wave are obtained. The amplitude and speed of the transmitted wave for an incident wave in the form of a soliton are calculated.     

Nature of "superluminal" barrier tunneling

We show that the distortionless tunneling of electromagnetic pulses through a barrier is a quasistatic process in which the slowly varying envelope of the incident pulse modulates the amplitude of a standing wave. For pulses longer than the barrier width, the barrier acts as a lumped element with respect to the pulse envelope. The envelopes of the transmitted and reflected fields can adiabatically follow the incident pulse with only a small delay that originates from energy storage. The theory presented here provides a physical explanation of the tunneling process and resolves the mystery of apparent superluminality.     

The role of Biot slow waves in electroseismic wave phenomena

The electromagnetic fields that are generated as a spherical seismic wave (either P or S) traverses an interface separating two porous materials are numerically modeled both with and without the generation of Biot slow waves at the interface. In the case of an incident fast-P wave, the predicted electric-field amplitudes when slow waves are neglected can easily be off by as much as an order of magnitude. In the case of an incident S wave, the error is much smaller (typically on the order of 10% or less) because not much S-wave energy gets converted into slow waves. In neglecting the slow waves, only six plane waves (reflected and transmitted fast-P, S, and EM waves) are available with which to match the eight continuity conditions that hold at each interface. This overdetermined problem is solved by placing weights on the eight continuity conditions so that those conditions that are most important for obtaining the proper response are emphasized. It is demonstrated that when slow waves are neglected, it is best to also neglect the continuity of the Darcy flow and fluid pressure across an interface. The principal conclusion of this work is that to properly model the electromagnetic (EM) fields generated at an interface by an incident seismic wave, the full Biot theory that allows for generation of slow waves must be employed.