Ion composition of the upper F -region

Abstract

In order to relate the work reported in this paper to the other experiments carried in the satellite Ariel I, a brief account of the aims of the ionospheric and solar experiments is relevant. The provision of an internal tape recorder, and the satisfactory expected life and orbital parameters possible, provided a unique opportunity for comprehensive study of the upper ionosphere. It was resolved to provide means not only to measure the primary parameters of the ionosphere—ionic composition and temperature, and electron concentration and temperature—but also to study the solar behaviour with a view to relating it to secular features in the ionospheric behaviour that became evident. At the time it was not practicable to provide means to monitor the solar helium II Lyman-α radiation likely most to affect the higher regions so it was resolved to monitor the H Lyman-a flux and the soft X-ray spectrum as indices of the behaviour of the chromosphere and corona, respectively. The H Lyman-a experiment failed on launch. The X-ray work, which was undertaken in collaboration with the University of Leicester, is reported later in this Symposium.