Influence of Channel Length, Return-Stroke Speed and Ground Conductivity on Horizontal Electric Field Associated with Nearby Lightning Return Strokes

Very few efforts have been dedicated to the horizontal electric field generated by lightning flashes since its value is much smaller than that of the vertical electric field. In fact, the horizontal electric field near the lightning channel may reach up to thousands of volts per meter or even more, and its destructive power cannot be ignored. Accurate calculation and reasonable parameter selection of the space horizontal electric field is of great importance in induction lightning protection and electromagnetic shielding. In this paper, Finite Difference Time Domain (FDTD) method was used to calculate the space horizontal electric field 50 m and 100 m away from the lightning channel. Three influencing factors, namely, the total length of the return stroke channel (H), the return-stroke speed (v) and the ground conductivity (sigma), were considered. Results showed that the horizontal electric field decreases nonlinearly with the increase of H and v, while increases nonlinearly with the increase of sigma. However, these influences become weak when H > 4000 m, v > 2c/3 (c is light speed), and sigma > 8.0x10(-4) S/m. The results provided an evaluation reference to the electric field intensity.