Generation of seed electrons in guided ionization waves in He–O2 mixtures: The effect of negative ion cluster formation

Physics of Plasmas. 2024. Vol. 31. No. 9. Article 093509.

N. L. Aleksandrov, A. A. Ponomarev, Syssoev A. A.

The kinetics of electrons and negative ions was numerically studied under the conditions, which are typical for multi-pulsed guided ionization waves in He flows ejected into ambient air. It was shown that, in He with a small admixture of O2 or air, O2- ions formed due to three-body electron attachment in the discharge afterglow are rapidly converted to O4- cluster ions in pulse off time. We suggested that seed electrons are generated at the leading edge of a pulse in two steps, and these steps are dissociation of O4- ions to form O2- ions followed by electron detachment from the O2- ions. The rate of O4- dissociation was calculated in He–O2 mixtures for various reduced electric fields on the basis of a Monte Carlo simulation. This rate, as well as the rate of electron detachment from O2- ions calculated previously, was used to simulate seed electron generation in a high-voltage nanosecond pulse in He–O2 mixtures for different gas pressures. It was shown that the formation of O4- ions drastically hinders the generation of seed electrons in multi-pulsed guided ionization waves in He–O2 and He–air mixtures.

Keywords: метод Монте-Карло, Monte-Carlo Method, low temperature plasma, низкотемпературная плазма