Book Description

The present state of our knowledge concerning the formation of positive and negative ions in the earth's normal ionosphere is reviewed. The main process by which positive ions and electrons are formed in the ionosphere is photoionization of neutral constituents by solar vacuum ultraviolet radiation. Negative ions are formed primarily by direct attachment of electrons to certain neutral constituents. Existing values of the cross sections and rate coefficients of these processes are presented and gaps in the present knowledge are discussed.