This article focuses on the bidirectional return-stroke propagation phenomenon in the initiation process of lightning return stroke. Different from the conventional return-stroke model, the return-stroke current waves in the bidirectional return-stroke model are considered to propagate simultaneously in both the upward and downward directions at two different speeds from the junction point, where the downward and upward leaders connect with each other. The finite-difference time-domain (FDTD) method in the two-dimensional cylindrical coordinate is employed for the calculation. From the simulation results of the bidirectional return-stroke model, it can be found that compared with the conventional return-stroke model, initial peaks will appear at the rising edges both for the vertical electric field and azimuthal magnetic field at the certain conditions. The influences of characteristic parameters, including the height of junction point, the propagation velocities of downward return strokes, and the ground conductivity, on the computed results are analyzed. To accurately reproduce the radiated electromagnetic fields, the bidirectional propagation model should be taken into consideration.

中文翻译：

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雷电电磁场计算的双向回程模型


本文主要研究雷电回击起爆过程中的双向回击传播现象。与传统的回程模型不同，双向回程模型中的回程电流波被认为从向下和向上先导连接的交汇点以两种不同的速度同时向上和向下两个方向传播。与彼此。采用二维柱坐标下的时域有限差分（FDTD）方法进行计算。从双向回程模型的仿真结果可以发现，与传统回程模型相比，在一定条件下，垂直电场和方位磁场都会在上升沿出现初始峰值。分析了结点高度、向下回程传播速度、地面电导率等特征参数对计算结果的影响。为了准确地再现辐射电磁场，应考虑双向传播模型。