Influence of Ionization Degrees on the Evolutions of Charged Particles in Atmospheric Plasma at Low Altitude

A zero-dimensional model which includes 56 species of reactants and 427 reactions is used to study the behavior of charged particles in atmospheric plasmas with different ionization degrees at low altitude (near 0 km). The constant coefficient nonlinear equations are solved by using the Quasi-steady-state approximation method. The electron lifetimes are obtained for afterglow plasma with different initial values, and the temporal evolutions of the main charged species are presented, which are dominant in reaction processes. The results show that the electron number density decays quickly. The lifetimes of electrons are shortened by about two orders with increasing ionization degree. Electrons then attach to neutral particles and produce negative ions. When the initial electron densities are in the range of 10¹⁰-10¹⁴ cm^-3, the negative ions have sufficiently high densities and long lifetimes for air purification, disinfection and sterilization. Electrons, O_2^-, O_4^-, CO_4^- and CO_3^- are the dominant negative species when the initial electron density n_e0≤10¹³ cm^-3, and only an electron and CO_3^- are left when n_e0≥10¹⁵ cm^-3. N₂+, N₄+ and O₂+ are dominant in the positive charges for any ionization degree. Other positive species, such as O_4⁺, N₃+, NO+, NO₂+, Ar₂+and H₃O+•H₂O, are dominant only for a certain ionization degree and in a certain period.