地闪弯曲通道在不同观察尺度下的回击电磁场特征分析  

Lightning return stroke electromagnetic field generated by tortuous channel under different observation scales

作　　者：万浩江[1] 陈亚洲[1] 王晓嘉[1] 

机构地区：[1]军械工程学院电磁环境效应国家级重点实验室,石家庄050003

出　　处：《电波科学学报》2016年第3期528-536,共9页Chinese Journal of Radio Science

基　　金：国家自然科学基金(No.51377171)

摘　　要：基于偶极子法建立了弯曲通道中任意倾斜通道段产生雷电回击电磁场的三维计算模型,给出了空间倾斜通道微元在柱坐标系下激发电磁场的解析表达式,以此为基础,研究了弯曲地闪通道的观察尺度对首次回击和后继回击电磁场计算的影响.结果表明:通道弯曲是导致雷电回击电磁场波形出现振荡的直接原因,无论是首次回击还是后继回击,近区电场基本上不会因为通道弯曲而出现振荡,通道弯曲及其观察尺度也基本不会影响所计算回击电磁场初始峰值(近场区和过渡场区的电场波形为初始拐点)的上升时间,但会影响回击电磁场波形的初始峰值(或初始拐点)、波形的振荡起伏程度以及波形的频谱能量分布,且通道的观察尺度越小、观测点的距离越远、通道回击电流的上升时间越短,对应回击电磁场波形中的振荡起伏越明显.Due to the tortuosity of real cloud-to-ground lightning channel,a 3D model of lightning electromagnetic field generated by a section of sloped lightning channel in the space is proposed according to the dipole method,and the analytic expressions for lightning electromagnetic field in the cylindrical coordinate system are presented.On this basis,the influence of observation scale for the channel on the calculation of lightning electromagnetic field generated by the first return stroke and subsequent return stroke is analyzed.The results show that the tortuosity of lightning channel is the direct reason of oscillation in the electromagnetic field waveform.There is nearly no oscillation in both first and subsequent return stroke electric field waveform in near-zone even for tortuous lightning channel.The channel tortuosity also has no influence on the rise time of electromagnetic field waveform.However,the initial peak value（or the initial knee point for the electric field waveform in near-zone and intermediate-zone）,the degree of oscillation,and the frequency spectral energy distribution of lightning electromagnetic field waveform are all seriously influenced by the channel tortuosity and the channel observation scale.The oscillation in lightning electromagnetic field waveform becomes visible under the situation of small observation scale,far observation distance,and short rise time of the return stroke current.

关 键 词：弯曲通道 雷电电磁场 观察尺度 首次回击 后继回击 

分 类 号：O441.4[理学—电磁学]