雷电回击电磁模型

The Lightning Return-Stroke Electromagnetic Models

雷电回击模型是研究较低电离层暂态光发射的产生、雷电辐射能量、地球电磁环境特征和雷电与各种物体和系统的相互作用的需要。雷电回击电磁模型是基于麦克斯韦方程组的模型,这些模型相对较新且是适合雷电电磁场计算的所有模型中最精确的模型。分析了雷电回击电磁模型中使用的4种回击通道表示方法的优点和缺点,这4种回击通道是:(1)空气中的良导线或电阻线;(2)嵌入电介质(非空气)中的线;(3)空气中加载附加分布串联电感的线;(4)空气中带附加分布并联电容的线。此外,本文描述和比较了电磁回击模型中使用的不同的激励方法:(1)底部带指定阻抗(或电路)的闭合的带电垂直线;(2)三角间隙电场源;(3)集总电流源。最后回顾和比较了适用于雷电回击电磁模型的典型的数值计算方法:时域和频域矩量法(MoM)和时域有限差分(FDTD)法。

Lightning return--stroke models are needed in studying production of transient optical emission in the lower ionosphere, the energetic radiation from lightning and characterization of the Earth＇s electromagnetic environment, as well as in studying lightning interaction with various objects and systems The lightning return stroke electromagnetic models are based on the based on Maxwell＇s equations These models are relatively new and most rigorous of all models suitable for computing lightning electromagnetic fields, We discuss advantages and disadvantages of four return--stroke channel representations： （1）a perfectly eonductingtresistive wire in air, （2）a wire embedded in a dielectric （other than air）, （3）a wire in air loaded by additional distributed series inductance, and （4）a in air having additional distributed shunt capacitance. Further, we describe and compare different methods of excitation used in electromagnetic return--stroke models： （1）closing a charged vertical wire at its bottom with a specified grounded circuit, （2）a delta--gap electric field source, and （3）a lumped current source. Finally, we review and compare representative numerical techniques used in electromagnetic modeling of the lightning return stroke method of moments （MoM） in the time and frequency domains and the finite difference time domain （FDTD） method.