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 N2 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