DENSITY PERTURBATION BY ALFVEN WAVES IN MAGNETO-PLASMA

In this article, we attempt to investigate the density perturbations along magnetic field by ponderomotive effects due to inertial Alfven waves (AWs) in auroral ionosphere. For this study, we take high-frequency inertial AWs (pump) and their nonlinear interactions with low-frequency slow modes of AWs in that region. The dynamical equations representing these wave modes are known as the Zakharov like equation, and are solved numerically. From the results presented here, we notice the density perturbations in the direction of background magnetic fields. We also find that the deepest density cavity is associated with the strongest magnetic fields. The main reason for these nonlinear structures could be the ponderomotive effects due to the pump waves. The amplitude of these density structures varies with time until the modulation instability saturates. From our results, we estimate the amplitude of most intense cavity as similar to 15% of the unperturbed plasma number density n(0), which is consistent with the observations. These density structures could be the locations for particle energizations in this region.