Towards a model of incoherent scatter signal spectra without averaging   over sounding runs
  This paper offers a model for incoherent scatter signal spectra without averaging the received signal over sounding runs (realizations). The model is based on the existent theory of radio waves single scattering from the medium dielectric permittivity irregularities, and on the existing kinetic theory of the plasma thermal irregularities. The proposed model is obtained for the case of monostatic sounding. The model shows that the main contribution to the received signal is made by ion-acoustic waves caused by certain spatial harmonics of the ions number phase density. The model explains the width and form of the signal spectrum by macroscopic characteristics of the medium, and its fine 'peaked' structure by characteristics of the ions number phase density. The notion of the weight volume is introduced to define the domain of wave vectors and velocities in the spatial spectrum of the ions number phase density which makes the main contribution to the formation of the scattered signal. This weight volume depends on the antenna pattern, the form of the sounding signal, and on the time window of spectral processing, as well as on ionospheric plasma macroscopic parameters: electron and ion temperatures, ion composition, and the drift velocity. Within the context of additional assumption about the ions number phase density, the proposed model was tested by the data from the Irkutsk incoherent scatter radar. The test showed a good fit of the model to experiment. 
Oleg .I. Berngardt