POSITIVE ION-NEUTRAL REACTIONS IN THE IONOSPHERE (REPRINTED FROM JOURNAL-OF-GEOPHYSICAL-RESEARCH, VOL 12, PG 4323-4329, 1965)

Daytime positive ion densities calculated using recently measured labo ratory ion-neutral reaction rate constants are compared with the NRL r ocket results between 120 and 220 km. The calculated O+ and N-2(+) den sities are found to be in good agreement with the ionospheric observat ions. The main N-2(+) loss process in this region is the reaction N-2( +) + O --> NO+ + N This reaction is also the major source of NO+ at 14 0 km. The charge-transfer reaction O-2(+) + NO --> NO+ + O-2 appears t o be a significant source of NO+ at 120 km and indeed may be the major source. The reaction O-2(+) + N --> NO+ + O will be significant at 12 0 km if the ratio of atomic to molecular nitrogen is as large as 10(-4 ). The fast O-2(+) loss in reaction with NO at 120 km at night require s a local ionization source greater than 1 O-2(+) ion/cc sec to mainta in the observed O-2(+) concentration. (C) 1965 American Geophysical Un ion.