Scattering of Electromagnetic Waves in the Presence of Wave Turbulence Excited by a Flow with Velocity Shear

It is well-known that an incompressible sheared flow with an inflection point in the velocity profile will result in the formation of turbulent vortices. In the case of compressible plasma flow with velocity shear ion acoustic fluctuations in addition to vortices will be generated. We present a detailed analysis of the excitation of such low frequency oscillations in a compressible plasma flow with velocity shear. To examine the process of excitation and nonlinear saturation of low frequency oscillations in the presence of a flow shear a nonlinear system of equations was derived. We employ a predictor-corrector method to solve this system numerically. Spectral analysis of the numerical solutions allows us to calculate the turbulent density spectra for different velocity profiles. We find that the impact of this turbulence associated with ion-acoustic wave fluctuations is considerably more significant and dominant than that due to turbulent vortices. On employing a single scattering perturbation theory we observe that the electromagnetic scattering from the turbulent density fluctuations of the flow results in shifted signal spectra above and below that of the source.
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