Multiple acceleration of electrons in the regions of high-power radio-wave reflection in the ionosphere

Abstract

In a rarefied plasma an electron acceleration under the influence of HF wave takes place in the plasma resonance region near to the wave reflection. The acceleration in itself is essentially collisionless, but in the ionospheric plasmas the collisions play an important role. The present paper discusses the influence of collisions and the Earth's magnetic field on the electron acceleration process. It has been shown that due to collisions and magnetic field the electrons acquire the ability to multiply cross over the resonance region which results in an intensification of the fast electron acceleration. The extent of the acceleration-caused modification of the fast electron distribution function and the value of the flux at fast electrons escaping into the magnetosphere are calculated. The theory is compared with experimental data on the ionospheric modification by intense radio waves. The theory is shown to agree with the observational data on the artificial airglow emission, additional ionization and plasma noise generation in the ionosphere. The possibility of the observation of new lines with high excitation potentials is predicted.