INVESTIGATION BY BACKSCATTER RADAR OF ARTIFICIAL IRREGULARITIES PRODUCED IN IONOSPHERIC PLASMA-HEATING EXPERIMENTS

The artificial ionospheric turbulence occurs in the ionosphere illumin ated by high power HF radio waves. There are a lot of irregularities s tretched along the geomagnetic field in this region. The investigation of the artificially disturbed ionospheric region is based on the rece ption of back scattered signals (BSS) which permits the basic paramete rs of this region to be estimated and its inhomogeneous structure to b e described. Experiments were carried out using 'Sura' heating facilit y in the frequency range of f = 4.7 - 9 MHz (ordinary mode) with the e ffective radiated power P-eff = 50-70 MW beamed vertically upwards. Th e most important dynamic and statistical BSS characteristics (the buil t-up time, the relaxation and autocorrelation times, the BSS amplitude spatial correlation function and power spectra) were measured using p robe waves in the frequency range of f(p) = 1.68-6 MHz that made it po ssible to obtain the basic parameters of the artificial irregularities . The model representation of a disturbed region in a form of a period ic structure gives a possibility to evaluate the scale of the structur e, the whole size of the disturbance and its power and to calculate th e main BSS characteristics. (C) 1997 Elsevier Science Ltd.