Incoherent scattering by free electrons as a technique for studying the ionosphere and exosphere: observations and theoretical considerations

Abstract

Incoherent scattering by the free electrons of the ionosphere has been predicted and offered as a technique for measuring the electron density profile both below and above the F region maximum. This paper reports observations which confirm the existence of the incoherent scatter and show that its intensity is essentially the predicted value. The observed Doppler broadening is considerably smaller than predicted. In the second part of the paper, an explanation for the reduced Doppler broadening is offered. The scatter is explained as arising from statistical fluctuations of electron density, the distribution of which is controlled by the positive ions. Computations of the temporal auto­ correlation function, and related power spectrum, of the scatter are presented. An additional possibility of using the incoherent scatter for mass-spectrometer measurements of the ionic constituents is out­lined.