The influence of individual evaluation of electron-impact ionization, attachment, and photoionization rates on positive streamer propagation

This study evaluates the individual effects of electron-impact ionization, attachment, and photoionization on streamer propagation to provide a deeper understanding of the streamer propagation mechanism and useful knowledge to obtain the best set of input data for verification and validation studies. The results show that streamers with higher electron-impact ionization rates have higher propagation velocities and lower electric fields, while those with higher attachment rates have slower propagation velocities and higher electric fields. Streamers with higher photoionization rates have lower electric fields at the head, but the velocity remains largely unaffected. The effects of different rates of ionization, attachment, and photoionization have been analyzed using an analytical solution called the diameter-speed relation.