Over the increasing phase of solar activity from 1974 to 1978 the F10.7 index increased from ~70 to ~180. Earlier studies of the N+2 ion based on the Atmosphere Explorer satellite measurements used data gathereed in 1974. A study of N+2 using 1978 measurements made during significantly higher solar EUV fluxes reveals a change in the relative importance of the major chemical processes. Photoionization of N2 is found to be the major source of N+2 in the F2 layer, by contrast with the charge exchange reaction of O+(2D) with N2, which was dominant for the lower solar activity. The increased electron concentrations enhance the importance of reactions involving electrons, thus permitting good determinations of the relevant reaction rate coefficients, which could not be done in the earlier studies. As such, the 1978 data provide a useful opportunity to confirm the photochemical scheme established earlier and to improve the accuracy of the determination of the rate coefficients for certain processes. Specifically, we determine the rate coefficients for dissociative recombination of N+2 with electrons, confirming laboratory measurements; we refine an earlier determination of the charge exchange rate coefficient for O+(2D) with N2 to (7¿3)¿10-11 cm3 s-1; and we determine the rate coefficient for quenching of O+(2D) by electrons, confirming a theoretical calculation. |