Results of experiments on modification of the sporadic e-layer by powerful hf radio waves

We present the results of experiments on modification of the sporadic E layer of the Earth’s ionosphere by a powerful vertical beam of HF radio waves. The experiments were performed at the “Sura” heating facility (Radiophysical Research Institute, Nizhny Novgorod) from May 31 to June 4, 2001. The main results were obtained in May 31 from 17:30 to 20:00 MSK, when the Es layer was fairly stable and the pump frequency was in the range where this layer was transparent. The diagnostics of the ionosphere was performed using X-mode probe waves in the frequency range fpr = 4.3−7.8 MHz. The ionosphere plasma heating was accompanied by an increase in the intensity of probe waves, reflected from the Es layer, with frequencies close to or slightly higher than the critical frequency of the layer. Artificial fluctuations of the reflected signal appeared in the entire frequency range of sounding. We consider the dynamical characteristics of the observed phenomena and their dependence on the frequency fpr and the parameters of the Es layer. © 2002 Plenum Publishing Corporation.