EMP Coupling Analysis Using the Frequency (Transfer Function) Method with the SCEPTRE Computer Program

The availability of digital computer time and scientific programming languages (such as Fortran) has, resulted in the use of the digital computer for electromagnetic pulse (EMP) coupling analyses. This report describes combining complex frequency domain analysis techniques with the SCEPTRE computer program to evaluate the time response of the current induced on a thin-wire scatterer when the scatterer has been excited by an arbitrary shaped electromagnetic pulse. The method is illustrated by performing an analysis for the current which would be induced by a fast rise time EMP (unit step) and a relatively slow rise time EMP (waveshape similar to that produced by a lightning stroke).     

Plane wave coupling to multiple conductor transmission lines abovea lossy earth

The current induced on an infinite multiple conductor transmission line located above a lossy homogeneous medium due to a transient plane wave is discussed. An exact solution is formulated in the frequency domain using a spatial transform technique. The widely utilized quasi-TEM approximation is derived directly from the exact solution with emphasis on the physical consequences of the assumptions made. Both frequency domain and time domain numerical results are presented for typical transmission structures and documented electromagnetic pulse (EMP) excitations. Comparison of the quasi-TEM approximation to the exact solution is made in order to study the validity of its application in EMP coupling problems. The modeling of the EMP source as an incident plane wave is examined by comparing the induced current due to a dipole source with its steepest-descent contribution     

静电放电电磁脉冲均匀辐射场模拟

为了研究静电放电电磁脉冲（ESDEMP）的特性,利用传统的静电放电电磁脉冲产生方法,通过静电放电模拟器在静电放电抗扰度试验平台上放电,产生了静电放电电磁脉冲,并测出了静电放电电磁脉冲的时域波形和频谱。在研究电磁脉冲模拟器的基础上,首次通过ESD模拟器和GTEM室的结合,在GTEM室内产生了均匀的、重复性和线性好的ESDEMP。实验表明,用TEMP室、GTEM室等大型装置产生均匀静电放电电磁脉冲辐射场的方案是可行的。     

Numerical Analysis of a Transmission Line EMP Simulator

A theoretical model is defined for an electromagnetic pulse (EMP) simulator for testing EMP effects on high altitude satellites. The simulator is composed of three flat-plate transmission line sections. The first and third sections are tapered to accommodate, respectively, a generator and a terminating resistor. This problem is analyzed in the frequency domain over those frequency components which are known to contribute most significantly to a typical EMP waveform. The analysis uses a numerical technique to solve the basic problem of an unknown current distribution on a curved, tapered strip, excited by a known electric field. The unknown current is solved by the method of moments, using triangular basis functions. As a check, input impedances are computed for the triangular dipole, showing good agreement with experimental results. For the transmission line simulator, computed input impedance, VSWR, power dissipated in the terminating resistor, and the power lost to radiation are presented as a function of frequency. The computed current distributions are used to calculate the electric fields between and immediately beyond the parallel plates. Although a considerable portion of power is converted to radiation at the higher frequencies, it is shown that at least within the working volume the electric field maintains a reasonably constant level.     

纳秒级电磁脉冲发生器的研制与相关寄生参数研究

为研究瞬态电磁脉冲故障注入对集成电路芯片的影响及其故障机理,基于Marx发生器原理和MOSFET开关特性,研制了一个全固态纳秒级电磁脉冲发生器.基于提出的HSPICE软件仿真等效模型,分析了发生器电路主要寄生参数对MOSFET开关特性的影响,并建立了相应的数学模型,为电磁脉冲发生器的研制提供了设计指南.实验结果表明:建立的数学模型精度为96.7%;基于二级Marx电路的电磁脉冲发生器可产生幅值可调（0~100 V）、脉宽可变（200~2 070 ns）、最快下降沿为32 ns的脉冲信号;在电磁探头下方5 mm处的测试线圈上可测得1 600 mV的感应电动势,并可利用该感应电动势来对芯片引入故障.     

大地对电磁脉中感应的电缆电流影响的数值计算

与电子系统相连的电缆被电磁脉冲感应形成的脉冲电流,构成了对电子系统的严重威胁。该文用时域有限差分法计算了大地电参数对感应电流的影响。计算获得了电缆上皮电流与电缆距地高度的关系,并与自由空间的结果进行了比较。     

External interaction of the nuclear EMP with aircraft and missiles

The general problem of external coupling of the nuclear EMP to metal structures is discussed with attention directed toward aircraft and missiles. Theoretical and experimental data are presented for the skin current and charge densities induced on aircraft. Recommendations for future studies are also given.     

通信电台电磁脉冲阻塞效应规律与作用机理

为揭示通信电台电磁脉冲阻塞效应机理,在受试电台正常工作状态下,借助注入耦合模块实验研究了阶跃脉冲串和双指数脉冲串对数字通信电台误码率的影响规律。引入电磁脉冲对受试设备影响时间的概念,建立了与连续波阻塞效应等价的电磁脉冲阻塞敏感判据。实验结果表明:电磁脉冲对受试设备的影响时间取决于脉冲波形,可通过效应试验测试确定。在电磁脉冲重复率较低时,受试电台的临界干扰电平与脉冲重复率无关,属于单脉冲效应;当脉冲重复率大于电磁脉冲影响时间的倒数时,受试电台的临界干扰电平随脉冲重复率增加而降低,属于多脉冲累加效应。将电磁脉冲在影响时间窗口内进行频谱分析,采用连续波带内多频阻塞效应模型进行验证,误差在2dB以内。     

电磁脉冲斜入射时无限长近地细导线表面电流的计算

本文应用时域有限差分（FDTD）方法研究电磁脉冲斜入射下无限长细导线的表面感应电流,并考虑了有耗地面的影响,该问题可以转换为二维问题来计算,从而大大节约计算资源,文中给出了各种情况下的感应电流计算结果。     

Pulse response of linear dipole antenna

Applications of transient electromagnetics include nonnuclear electromagnetic pulse (EMP) effects on electronic systems to evaluate system vulnerability. A basic component used in the mathematical modeling of systems for EMP vulnerability is the linear dipole antenna. Wu has derived an approximate analytical solution for the pulse reflected from the feed point of a linear dipole antenna for an incident ideal step function of current. The solution does not include the part associated with the very high frequency components because of an approximation used in evaluating the integral describing the reflected pulse. The approximation is eliminated and a simple analytical solution is given that describes that portion of the step function response associated with the very high frequency components. Numerical evaluation of the solution demonstrates convergence with Wu's approximate solution.     

Radiation and scattering from electrically small conducting bodies of arbitrary shape

A simple moment solution is given for low frequency electromagnetic scattering and radiation problems. The problem is reduced to the corresponding electrostatic and magnetostatic problems. Each static problem is solved using the Method of Moments. The surface of the perfectly conducting scatterer is modeled by a set of planar triangular patches. Pulse expansion functions and point matching testing are used to compute the charge density in the electrostatic problem. For the magnetostatic current a set of charge-free vector expansion functions is used. The problem is formulated assuming the scatterer to be in an unbounded homogeneous region. Scatterers of various shapes, such as the circular disc, the sphere, and the cube are studied. Special attention is paid to a conducting box with a narrow slot. The computed results are the scattered fields, the induced charge and current distributions, and the induced electric and magnetic dipole moments. These are in close agreement with whatever published data are available.     

Currents and fields of thin circular and elliptical loops

Approximate solutions for the current of thin circular and elliptical loops have been determined on the basis of an asymptotic antenna theory. The fields at and around the center have been calculated to illustrate the broadband behavior of these structures when used as electromagnetic pulse (EMP) simulators. Fields calculated with this approach and those measured in an actual EMP simulator are compared. The comparison indicates that the model presented might be adequate for describing the salient features of the fields of a real system and could provide an alternative to experimental field mapping efforts     

高空核电磁脉冲照射下车辆表面感应电流研究

高空核电磁脉冲(HEMP)照射下车辆表面感应电流的研究是装甲车辆电磁防护工作的组成部分。根据IEC6100发布的高空核电磁脉冲波形标准,文中建立了高空核电磁脉冲照射下车辆表面感应电流仿真电磁模型,并使用基于FDTD算法的CST软件进行仿真。通过改变HEMP照射方向和去除炮管部位,对比研究不同频点的车辆表面感应电流最大值和峰值区域的变化情况。实验结果表明,不同角度的车辆表面感应电流最大值与照射方向车辆表面结构的复杂度呈正相关变化,在炮管部位有远高于其它部位的感应电流。文中车辆最大感应电流参考值为1.82×103 A/m,重点防护频段为0~40 MHz。     

电磁脉冲对战场的影响

介绍了电磁脉冲对武器装备的作用机理,分析了自然电磁脉冲和电磁脉冲武器的特点,研究了2种电磁脉冲对战场的威胁;在此基础上,提出提高电磁脉冲防护能力,提高抗电磁脉冲训练水平,创新电磁防护技术等强电磁脉冲环境下装备和作战的应对措施.     

Capacitance of dielectric coated cylinder of finite axial lengthand truncated cone isolated in free space

The capacitance of dielectric coated metallic cylinder and truncated cone are evaluated using the method of moments based on the pulse function and point matching. The analysis is based on the boundary condition for the potential on the conductor surface and the normal component of the displacement density at the dielectric-free space interface. The total free charge on the conductor surface is found from the inversion of a matrix partitioned into submatrices. Numerical data on the capacitance and charge distribution are presented     

Theoretical and experimental characterization of theEMP-interaction with composite-metallic enclosures

A numerical procedure is developed for the prediction of the electric and magnetic field distribution inside an enclosure having aluminum and carbon-fiber reinforced composite (CFRC) walls, illuminated by a transient electromagnetic plane wave. The composite panel is simulated by an effective layer model; time-domain surface impedance boundary conditions are enforced on the external faces of the composite slab, to express the relations among the tangential electric and magnetic field components. A coupling model for the calculation of the current induced along thin wires inside the enclosure is presented. The proposed models are implemented in a three-dimensional (3-D) finite-difference time-domain (FDTD) procedure, which is applied to the analysis of the shielding performances of an aluminum box with one CFRC face, illuminated by a transient electromagnetic wave. The computed results are compared with measured data obtained by using a full scale EMP generator     

Transient response of a distribution circuit recloser and controlunit to a high-altitude electromagnetic pulse (HEMP) and lightning

An analysis of the response of a power system distribution line recloser unit to a high-altitude electromagnetic pulse (HEMP) and a lightning direct-strike excitation is presented. From details of the configuration of the system, physical and mathematical models are developed, and a study of possible HEMP responses is conducted. Two voltage and two current responses at selected points within the system are studied for both the HEMP and lightning stresses. The possibility of simulating the HEMP responses is also discussed, with predicted and measured responses being provided for the advanced research EMP simulator (ARES). Based on a comparison of measured and predicted currents on one of the conductors, the model is shown to agree reasonably well with the measurement. With such a model, it is possible to perform parametric studies of the HEMP response of the system     

Different pulse shapes to obtain small fiber selective activation by anodal blocking--a simulation study

The aim of this study was to investigate whether it is possible to reduce a charge per pulse, which is needed for selective nerve stimulation. Simulation is performed using a two-part simulation model: a volume conductor model to calculate the electrical potential distribution inside a tripolar cuff electrode and a human fiber model to simulate the fiber response to simulation. Selective stimulation is obtained by anodal block. To obtain anodal block of large fibers, long square pulses (> 350 micros) with a relatively high currents (1-2.5 mA) are usually required. These pulses might not be safe for a long-term application because of a high charge per pulse. In this study, several pulse shapes are proposed that have less charge per pulse compared with the conventional square pulse and would therefore be safer in a chronic application. Compared with the conventional square pulse, it was possible to reduce the charge with all proposed pulse shapes, but the best results are obtained with a combination of a square depolarizing pulse and a blocking pulse. The charge per pulse was up to 32% less with that pulse shape than with a square pulse. Using a hyperpolarizing anodal prepulse preceding a square pulse, it was not possible to block nerve fibers in a whole nerve bundle and to obtain reduction of a charge per phase. Reduction of the charge could be achieved only with spatially selective blocking. The charge per phase was larger for the combination of a hyperpolarizing anodal prepulse and a two-step pulse than for the two-step pulse alone.     

电磁脉冲在地下的传播特性研究

对于电磁脉冲的传播来说,大地是一道天然的障碍,因此研究电磁脉冲在地下的传播规律,并将其用于线路和设备的抗电磁干扰,是很有意义的。本文分析了HEMP电场在地下的传播规律,并比较了HEMP和雷电磁脉冲(LEMP)、超宽带电磁脉冲(UWB EMP)在地下的传播情况,比较了HEMP在地下和地上的传播情况,结果表明:高频电磁脉冲电场在地中随深度增加而快速减小,低频电磁脉冲变化较小;高频电磁脉冲电场随大地电导率减小而增大、脉宽变宽,随大地介电常数增大而减小,随入射波极化角和方位角增大而减小,随俯仰角增大而增大。然后,根据电磁脉冲在地下的传播规律提出了电磁防护措施和建议。本文的研究有利于指导地下设备的电磁防护设计。     

单片机的ESD EMP效应及加固技术研究

ESD EMP(静电放电产生的电磁脉冲)具有上升沿陡、频带宽和峰值大等特点,对电子系统具有很强的干扰和破坏作用。为研究ESD EMP对电子系统的影响,以单片机为实验对象,对单片机系统进行了ESD EMP辐照效应实验。实验表明,单片机系统在ESD EMP作用下,会出现10多种故障现象。文中在实验基础上研究了单片机加固技术。