Ionospheric Composition and Reactions

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Science  02 Feb 1968:
Vol. 159, Issue 3814, pp. 489-498
DOI: 10.1126/science.159.3814.489


Recent measurements of ion densities in the ionosphere seem to be more or less compatible with current data for ion-molecule reaction rates in some parts of the ionosphere under conditions in which a steady state prevails. There is no such agreement for the upper ionosphere, where the densities of He+ and H+ are difficult to understand in terms of present concepts concerning the relevant production and loss processes. Sources of ionizing radiation are needed to explain night- time observations in the E region and perhaps also in the F region. The D region remains a poorly understood laboratory of negative-ion and positiveion chemistry, where neither observation nor theory is as yet adequate.