Role of Plasma Inhomogeneities in the Generation of Broadband Waves in the Polar Ionosphere

It is shown that plasma instability associated with an in-homogeneous energy density distribution can lead to the excitation of electrostatic ion-cyclotron and oblique ionacoustic waves generated in the presence of inhomogeneous electric field and shear in the ion parallel drift velocities. Microprocesses associated with plasma inhomogeneities are studied on the basis of data from satellite and sounding rocket. By numerical stability analysis it is demonstrated that inhomogeneous-energy-density-driven instability (IEDDI) can be a mechanism for the excitation of small-scale plasma inhomogeneities. The Local Intermittency Measure (LIM) method also applied the rocket data to analyze irregular structures of the electric field during rocket flight in the cusp. A qualitative agreement between high values of the growth rates of the IEDDI and the regions with enhanced LIM is observed. This suggests that IEDDI is connected to turbulent non-gaussian processes.