地面附近云闪电磁环境测量研究

Lightning discharge could be classified as cloud-to-ground lightning (CG) and cloud lightning, depending on whether it touches the ground. Although cloud lightning makes up over 2/3 of all flashes, it has not deserved sufficient attention as extensive as CG.. Recently, the threats imposed by lightning electromagnetic pulse (LEMP) on micro-electronic equipment both on surface and aloft are more and more intensive, therefore, it is quite necessary to reconsider the protection against LEMP. Based on these consideration, the objective of our project are mainly concerned with the following basic studies : 1) numerically simulation and analysis on the LEMP of cloud lightning; 2) theoretical and experimental studies on the measurement tech of LEMP horizontal electric field component, 3D electric field and magnetic field with high performance and compact structure; 3) designing these dedicated test equipment to establish the LEMP electric and magnetic field measurement system in time domain; 4) analysis and studies on the electromagnetic environment on the ground surface caused by lightning by conducting field observations; 5) characterizing the statistics rules of the LEMP produced by cloud lightning both in time and frequency domain, especially the horizontal electric field component, by advantage of accurate positioning of striking point and type identification. All these work aim at serving LEMP protection and laying a foundation for the further development of LEMP measurement in the storm cloud, which plays an important role in assuring the normal operation of the electro- and electric devices and system in both aviation, spaceflight and these on the earth.

自然界闪电按其是否接触地面分为云闪和地闪，云闪不触地，发生率占全部闪电2/3以上，但至今研究不多。当今，闪电放电电流电磁辐射产生的LEMP（雷电电磁脉冲）对空中和地面上微电子设备的威胁日趋严重，加强对LEMP的防护已十分迫切。本项申请首先对云闪LEMP进行数值分析，并专门研究地面附近LEMP水平电场测量技术和高性能、高效率三维电场、三维磁场测试技术，研制专用测试设备，组建LEMP电场、磁场时域波形测量系统，利用室内外实验条件及野外实验条件，对自然闪电在地面附近形成的电磁环境进行全面测试和研究。结合闪电定位结果，提高对云闪的识别精度，给出云闪在地面附近形成的LEMP时域特性、频域特性、环境特点及统计规律，特别是LEMP水平电场的特性。为从根本上解决LEMP的防护问题提供依据，亦为进一步发展空间LEMP环境测量技术奠定基础。这对确保航空、航天及地面电子、电气设备及系统的安全运行具有重要意义。

鉴于国内外迄今对云闪LEMP（雷电电磁脉冲）的测量数据极少且仅限于对其地面附近垂直电场的测量，本项目首次研制成功技术先进可在地面附近分别测量LEMP三维电场和LEMP三维磁场的电子系统，构建了具备被测波形提取和失真矫正波形的数据处理系统与标定系统。观测到大量地闪LEMP三维电场与三维磁场波形和一定数量可供研究的云闪LEMP三维电场与三维磁场波形。并通过对雷电的潜势预报和临近预报以及闪电回波探测方面的研究，提高了雷电潜势预报预警时间，并为利用双线偏振多普勒雷达进行雷电临近预警及闪电回波探测开辟了可行的通道。针对LEMP测量系统等电子设备及系统的电磁防护问题，研究了FDTD算法如何用于CFRP电磁特性的分析；针对FDTD稳定性问题提出了三类新算法；针对精细结构和斜入射下周期结构问题提出了四类FDTD新算法，对精细结构LEMP辐射场耦合问题进行了数值分析。这对研究解决航空、航天及地面电子电气设备及系统对LEMP的防护问题具有重要意义。