Soil ionization phenomenon around grounding electrode under lightning impulse

Knowledging the ionization phenomenon of soil neighboring the grounding electrode is the fundament to correctly simulate the transient property of grounding devices. Soil is a solid medium, so the ionization phenomenon in soil is difficultly observed. The impulse breakdown electric field of soil is summarized, and the soil ionization phenomena under different medium were studied by X-ray film in this paper, and the soil ionization mechanism is discussed.