加速电荷法快速求解雷击高塔辐射电场

雷击高塔时会在周围形成很强的电磁场,分析高塔辐射电磁场对雷电研究和雷电防护具有重要意义。就电磁场中的辐射电场部分,根据加速运动电荷产生辐射电场的基本原理,将雷电流等效为运动电荷,分别计算MTLE(Modified Transmission Line with Exponential Decay,回击电流随高度以指数减小)回击通道和高塔中电流产生的辐射电场,进而得出雷击高塔总辐射电场。结果表明,高塔辐射电场在总辐射电场中所占比例很大,在初始时间总辐射电场波形不断振荡出现多个峰值,然后缓慢下降,其多次振荡波形主要取决于高塔中雷电流的多次反射和透射过程。高塔上方回击通道对辐射电场有一定的贡献,提高了总辐射电场的首次峰值,使得电场强度幅值得以增加。加速电荷方法直接给出了每个过程所辐射出的电场,避免了常规计算方法中复杂电流的积分和微分运算过程,也有助于理解雷击高塔辐射机理。

Fast Analysis of Radiated Electric Field for Lightning Strikes to Tall Towers Using Radiation Mechanism of Accelerated Charges

When the lightning strikes a tower, a strong electromagnetic field will form in the surroundings. The analysis of the EM field has great significance for lightning protection and lightning research. For the electric field portion of the EM field and based on the radiation mechanism of accelerated moving charges, this paper views the lightning current as moving charges, and calculates the radiated electric field produced by the currents in MTLE (Modified Transmission Line with Exponential Decay) return channel and the tower to get the total radiated electric field. The result shows that the radiated electric field in the tower makes up a large part of the total radiated electric field. At the initial time, the waveform of the total radiated electric field oscillates with multi-peak and then slowly descends. The multiple oscillating waveforms mainly depend on the multiple reflection and transmission of the lightning current in the tower. The return channel above the tower also contributes to the total radiated electric field, it increases the first peak of the total radiated electric field and enhances the strength of the overall electric field. The method of accelerated charges gives the electric fields directly, avoids the integration and differential operation of the complex current in the conventional calculation method, and helps to understand the radiation mechanism of lightning strike with tall towers.