Parametric excitation of high frequency plasma oscillations in the ionosphere by a powerful extraordinary radio wave

Abstract

The generation process of short wavelength (upper-hybrid and electron cyclotron) plasma oscillations resulting from induced scattering of a high power extraordinary radio wave by ions is studied. The threshold field E thr determined by collisional damping of the excited waves is calculated. The minimum value E thr is shown to be ≈ 1 V/m. This value is reached near the reflection level of the extraordinary wave when its frequency is situated between the electron gyroharmonics nω Be . Such a value can be easily exceeded in the heating experiments due to Airy swelling of the pump wave near the reflection level. In the cases nω Be − ω 0 ⪡ ω Be and ω 0 < 2 ω Be the instability quenches because of the absence of plasma oscillations with frequencies close to the pump wave frequency.