摘要
雷暴过程中,云闪发生频次约占总闪电频次的2/3以上;但由于云地闪对人类危害较大,目前对其研究较多。随着微电子技术的发展,云闪的电磁辐射特性也越来越受到重视。将云闪的放电通道近似为一斜向通道,考虑镜像电流,将回击电流近似为水平偶极子与垂直偶极子的叠加,根据Maxwell方程,推导了云闪斜向通道电磁场计算模型。通道基电流选取脉冲函数,在MTLL传输模型下计算了斜向放电通道在地面1~200 km处激发的电磁场波形。计算结果表明云闪斜向放电通道中水平偶极子与回击点高度对近场电磁场的影响较大。随着距离的增加,影响越来越小;在大于50 km的远场区,其影响可以忽略。
Models for calculation of cloud-ground lightning electromagnetic field usually assume a straight and vertical lightning channel,but cloud-ground lightning accounts for only 20% of the entire Lightning,most of the remaining is intracloud lightning. In order to study the discharge characteristics of intracloud lightning return stroke,the discharge channel a diagonal channel will be approximated. Considering mirror current,and according to the dipole theory and Maxwell equations the electromagnetic field calculation model of oblique channel is derived. Selecting double exponential function as the channel base current and using MTLL transmission model,the electromagnetic wave in the ground 1 ~ 200 km excited by oblique discharge channel be calculated. The calculation results indicate that the Horizontal dipole and the height of return stroke point will have a great influence on electromagnetic field of near-field region. With the increase of distance,the influence is more and more unimportant. When the distance > 50 km,the impact can be ignored.
出处
《科学技术与工程》
北大核心
2014年第25期6-11,17,共7页
Science Technology and Engineering
基金
"十一五"国家科技计划项目(2008BAC361305)资助
关键词
闪电电磁场
云闪
斜向通道
lightning electromagnetic field intracloud lightning oblique discharge channel
