Dynamic characteristics of stimulated radio emission from ionospheric plasma

Features of Excitation of Stimulated Electromagnetic Emission of the Ionosphere Modified by an Oblique High-Power Radio Wave

“…1. Here, the solid faint lines show the dependences of the SEE intensity on the inclination angle of the antenna beam for the stage of the maximum SEE level observed within 1−−3 s after the pump-on, and the dotted lines, for the stationary stage which takes place after the overshoot effect develops (i.e., when a decrease in the SEE intensity occurs after the stationary level of SEE is reached) [11]. All the dependences are normalized to the maximum SEE intensity observed in this measurement cycle at ∆f = −11 kHz for the southward zenith inclination angle θ = 4 • of the antenna beam.…”

“…It should be emphasized that correlation between the generation of the thermal SEE components (DM and BC) and the development of ASII was mentioned in a number of earlier papers (see, e.g., [11,13,18]). The obtained fairly good coincidence between the angular dependences of the intensities of the DM and BC components and the corresponding angular dependence of the ASII intensity can be considered another important proof that the generation mechanisms of the above-mentioned SEE components can be closely related to generation of small-scale irregularities.…”

“…For θ ≈ 8 • −−12 • , a pronounced maximum of the SEE intensity with a contrast of 5−−8 dB (with the higher contrast for the larger negative detunings) is observed for the three detunings. Since the stationary levels of intensity of the DM and BC components for such pump-wave powers undergo saturation and, therefore, depend only weakly on the pump-wave power and the ionospheric parameters [11], such a notable maximum of the SEE intensity at the stationary stage of AIT development can be indicative of a fairly strong variation in the SEE generation conditions and, therefore, in the properties of the excited ionospheric turbulence. Similar results concerning the relationship between SEE intensities in the sectors of northward and southward inclinations (for θ = ±8 • ) were obtained later in the experiment described in [16].…”

“…Study of the SEE features, which permits diagnostics of high-and low-frequency plasma processes in the perturbed ionospheric region without using additional technical means of sounding in the passive-radar mode, has been the objective in a large number of papers (see, e.g., [11][12][13][14] and references therein). At present, empirical characteristics of separate components of the SEE spectrum are studied well enough and theoretical models explaining their most important properties are proposed for the main SEE components, namely, the down-shifted maximum (DM), the broad continuum (BC), the narrow continuum (NC), and the broad up-shifted maximum (BUM).…”

Properties of the thermal narrow-continuum component in the spectrum of stimulated ionospheric emission

“…According to the studies performed in the middle [3][4][5][6][7][8][9] and polar [1,[10][11][12][13][14] latitudes, the SEE in its stationary state, which is usually reached a few seconds (or a few tens of seconds) after the interaction begins, is a composition of more than ten separate spectral structures (radiation components), which is evidence for the variety of the plasma processes occurring simultaneously in the perturbed region (PR) of the ionosphere. An overview of the results obtained in these experiments is given in, e.g., [15][16][17].…”