Electric Field in a Positive Streamer in Long Air Gaps

A numerical simulation of a positive streamer in long (up to 3 m) air gaps under normal conditions was performed within the 1.5D model taking into account the ionization expansion of the channel. It is shown that the average electric field in the channel and the field required to bridge the discharge gap are not universal values and strongly depend on the regime of streamer acceleration after its initiation. In particular, these fields can vary in the range of 3.4–11.2 kV/cm in air at atmospheric pressure, depending on the change in the external electric field in space and time in the initial phase of streamer development.