Metastable Atomic Oxygen Ions in Ionospheric Plasma

Abstract

In this paper, production of atomic oxygen ions in the F-region of the ionosphere due to the photoionization of atomic oxygen atoms by Solar XUV is considered. Knowing the transition probability for the ground and different excited states, the rates of production of atomic oxygen ions in the ground and various excited states are computed. By considering various production and loss mechanisms, the equilibrium concentration of atomic oxygen ions in the ground and excited states are computed in the height range 120–320 km. In particular, the various de-excitation mechanisms and their contributions for the concentration of metastable ions O+(2P) and O+(2D) are determined under different de-excitation mechanisms and for various rate coefficients for the important de-excitation processes. It was found that most of the atomic oxygen ions are in the ground state. The equilibrium concentration of O+(2P) peaks at 160–200 km, the actual height depending on the rate coefficient for the reaction O+(2P) + N2 → N+ + O. Similarly, the equilibrium concentration of O+(2D) was found to be mainly controlled by the rate coefficient for the reaction O+(2D) + N2 rarr; N+2 + O. Line intensities for some of the transitions involving the metastable atomic oxygen ions are computed and compared with the experimental results.