Determination of the lifetime of molecules O 2 + and estimation of the flux of penetrating electrons generating a cloud of excess concentration of O 2 + in the ionosphere at altitudes above 220 km

Abstract

The occurrence of anomalous (nonthermal) profiles of green emission of oxygen atoms detected with a Fabry-Perot spectrometer in auroras with the effect of a rapid decrease in the intensity of the wings of their dissociative component has been investigated. Based on an analysis of these measured profiles, it has been found that the characteristic time of recombination of a molecular oxygen ion at altitudes of 200–400 km is about 5–7 s. It appears that these molecular ions occur in a horizontally limited region of the auroral ionosphere as a result of ionization by a space localized flux of soft electrons with energies of 0.2–0.4 keV penetrating up to altitudes of 200 km. The estimation of the electron flux produces a value of 1010–1013 electrons cm−2 s−1. They generate the excess concentration n(O2+ ) ~ 5.6 × 105 cm−3.