Numerical modeling of nonlinear ionization waves propagating through atmosphere
Cheng-Ling Kuo1*
1Institute of Space Science, National Central University, Taiwan
* presenting author:Cheng-Ling Kuo,
A sprite streamer is the ionization wave propagating through atmosphere. An electron can exponentially grow to the electron seed with 104 e- due to cosmic ray ionization. The electron mobility is at least 100 times of ion mobility. The electrons moving faster than ions cause the positively and negatively charged shell in the both opposite edges of the electron seed. The local electron field plus to background electric field can exceed the breakdown electric field. The high electric field will ionize more electrons and ions ahead the positively charged edge. More electrons will move in the reversed direction of electric field behind the positively charged head. The filled region with more ions and less electrons forms in the positively charged head of streamers. The positively charged head propagates through atmosphere due to electrical breakdown of gases. The peak electric field driven by the positively charged head was called by “ionization wave”. In our numerical work, we present the governing equation of ionization waves and their simulations at normal atmospheric pressure (760 Torr) and at an altitude of 70 km (0.05 Torr). The velocity of ionization wave in the standard atmosphere is ~ 106 m/s, which is much greater than the electron drift velocity (104-105 m/s). We also study the chemical active particles behinds the ionization wave and estimate the degree of ionization after the passage of streamers. The streamers are one of most important features in atmospheric discharge phenomena, such as sprites.

Keywords: atmospheric discharge, ionization wave, sprite streamer, sprites