Electron swarm parameters and Townsend coefficients of atmospheric corona discharge plasmas by considering humidity

Abstract

Humidity is a critical factor in atmospheric corona discharge. Fluid dynamics models have become a common method to explore the detailed corona discharge characteristics in humid air. However, the models require the specification of some key parameters, such as electron swarm parameters and Townsend coefficients, which strongly depend on the electron energy distribution function (EEDF). In this paper, the EEDFs of dry air and water vapor are compared by solving the electron Boltzmann equation using classical the two-term approximation. Moreover, electron drift velocity in dry air and water vapor are compared and validated. Finally, effects of humidity on the electron swarm parameters and Townsend coefficients are also discussed. The results show that the electron drift velocity in dry air and water vapor in this paper is well consistent with the previous experimental results for a wide range. It is concluded that the humidity could increase the electron mobility coefficient and decrease the electron diffusion coefficient in low reduced electric field, which are insensitive to humidity in high reduced electric field. The strength of ionization and attachment reactions are both enhanced by humidity, and the corona onset electric fields increase with the increase in humidity.