Photoionization and Optical Emission Effects of Positive Streamers in Air at Ground Pressure

A positive streamer in a weak electric field in air at ground pressure is investigated by utilizing a recently developed photoionization model based on the radiative transfer theory. The modeling results on the streamer emissions demonstrate that blue emissions of the second positive band system of N 2 dominate the streamer spectra, in contrast to streamers in predominately red sprite discharges observed at low air pressures at high altitudes in the Earth's atmosphere.