中文摘要：

由于雷击回击过程发生了强烈的电荷中和，会在周围空间形成强烈的电磁脉冲，对各种电气设备产生干扰。为此，对回击通道周围的电磁场进行模拟，提出了基于时域有限差分法的电磁场数值计算方法。雷电流模型采用双指数函数与Heidler函数组合的函数模型，回击通道采用改进型的DU模型。将模拟的结果与已有文献的结果进行比较，得出时域有限差分法在模拟雷击回击通道周围电磁场上具有一定有效性。模拟结果表明：雷电回击通道周围空间的电磁场受到回击速度、大地相对介电常数、大地电导率等因素的影响。电场的初始峰值随回击速度的增加而减小，磁场随回击速度的增大变化不大，只是略微有所上升；电场随着大地相对介电常数的增加而增加，波形变越来越陡峭；电场的初始峰值随着电导率的减小而增大，波形上升变的越来越陡峭，这些模拟结果与实测雷电电磁场变化是一致的。

英文摘要：

The electromagnetic pulse, caused by lightning, will be produced around the return stroke space during the process of Lightning discharge which disturbs electrical equipment. To this end, the electromagnetic field around the channel is simulated, and the numerical method of electromagnetic field based on finite difference time domain method （FDTD） is proposed. The lightning current model adopts the function model of the combination of the double exponential function and the Heidler function, and the improved DU model is adopted for the lightning return-stroke channel. The simulation result is com- pared with existing literature, and obtained that the effectiveness of the FDTD method is effectiveness on simulating the electromagnetic field around the lightning return-stroke channel. The simulation result shows： The electromagnetic field around the lightning strikes channel is affected by the factors such as the speed of the return strike, the relative permittivity of the earth, the earth＇s conductivity and other factors. The initial peak of the electric field decreases with the increase of the return strike speed, and the magnetic field increases little with the increase of the return strike speed. The electric field increases with the increase of the relative permittivity of the earth, and the wave shape becomes more and more steep. The initial peak of the electric field increases with the decrease of the conductivity, and the waveform will become steeper and steeper. The simulation results are consistent with the measured lightning electromagnetic field.