Positive ion-neutral reactions in the ionosphere

Daytime positive ion densities calculated using recently measured laboratory ion-neutral reaction rate constants are compared with the NRL rocket results between 120 and 220 km. The calculated O+ densities and N2+ densities are found to be in good agreement with the ionospheric observations. The main N2+ loss process in this region is the reaction This reaction is also the major source of NO+ at 140 km. The charge-transfer reaction appears to be a significant source of NO+ at 120 km and indeed may be the major source. The reaction will be significant at 120 km if the ratio of atomic to molecular nitrogen is as large as 10−4. The fast O2+ loss in reaction with NO at 120 km at night requires a local ionization source greater than 1 O2+ ion/cc sec to maintain the observed O2+ concentration.