Strong-Field Electromagnetic Wave Interaction with Anisotropic Plasmas

Abstract

Investigations of strong-field electromagnetic wave interactions with plasmas have been conducted. In the nonresonant frequency regions, the electron velocity distribution function is Maxwellian and considerations based on Maxwellian theory agree with experiment. At resonant and near-resonant frequencies considerations based on an electron velocity distribution which is non-Maxwellian explain the observations if enhanced electron diffusion is absent. However, at near-resonant frequencies, enhanced electron diffusion due to strong fields can be of great significance in reducing the electron density.

Kinetic Approach to Self Modulation of an Amplitude Modulated Wave in Magnetoplasmas

“…We consider a weakly ionized plasma in which (a10-alO-* + a,o-a,o-* + a,o- the increase in collision frequency; therefore, the absorption at crests is small and near troughs it is large; this pattern results in the overmodulation of the wave, whereas for the ordinary mode the absorption coefficient increases with the collision frequency; this pattern results in the demodulation of the wave. These results for the extraordinary mode are in qualitative agreement with the experimental results obtained by Bachynski and Gibbs [1969]. When the amplitude modulated wave is received at the ground after propagating a certain distance in the ionosphere, the extraordinary mode will be absorbed within 5 to 6 km of its propagation inside the ionosphere (owing to high absorption coefficient at gyroresonance) and only the ordinary mode will reach the receiver.…”

“…The phenomenon of self modulation of an amplitude modulated electromagnetic wave in a magnetoplasma has been theoretically investigated by Hibberd [1957], King [1959], Ram and Kaw [1967], and Sodha and Sawhney [1970]; this phenomenon has been experimentally observed by Mitra [1954], Aitchison and Goodwin [1955], Cutolo [1964], and Bachynski and Gibbs [ 1969]. Such observations have been limited to the interesting subject of gyroresonance.…”