СРАВНЕНИЕ СПЕКТРАЛЬНЫХ ХАРАКТЕРИСТИК УЗКОПОЛОСНОГО ИСКУССТВЕННОГО РАДИОИЗЛУЧЕНИЯ ИОНОСФЕРЫ ПРИ Х-НАГРЕВЕ ВЫСОКОШИРОТНОЙ F-ОБЛАСТИ ИОНОСФЕРЫ НА ЧАСТОТАХ НИЖЕ И ВЫШЕ КРИТИЧЕСКОЙ ЧАСТОТЫ Х-КОМПОНЕНТА СЛОЯ F2

Abstract

The paper presents the results of investigating generation conditions and features of the narrowband stimulated electromagnetic emission (NSEE) induced by an extraordinary (X-mode) HF pumping into the high-latitude ionosphere F region. It was shown that NSEE spectral features were recorded at a distance of more than 1100 km from the heating facility. Distinctive features of NSEE discrete spectral lines at the pump frequencies fH below and above the F2 layer X-component critical frequency (fH < fXF2 and fH і fXF2) were analyzed. It was found that the NSEE spectrum contains the strongly pronounced discrete lines ordered by the electrostatic ion cyclotron frequency for the atomic oxygen ions (O+). When fH < fXF2, the multiple downshifted and upshifted spectral components (Stokes and anti-Stokes modes, respectively) were excited in the NSEE spectra. When fH і fXF2, the Stokes modes were only generated. The plausible mechanisms for the NSEE excitation by an X-mode HF pump waves are discussed.