Multiple scattering from random plasma inhomogeneities

Small-angle multiple-scattering is considered from randomly spaced cylindrical plasma striations. It is shown that multiple scattering from several underdense plasma clouds can cause considerable backscatter even though a single undense cloud is capable only of deflecting the ray through fairly small angles. In a case in which the deflection angles are small and many deflections occur before a ray passes through the scattering region, the ray density can be shown to satisfy a Fokker-Planck transport equation. A diffusion coefficient is obtained for this equation for the case of cylindrical Gaussian striations by means of a numerical raytracing program. The transport equation is solved by a finite-difference method to obtain scattering patterns and waveform distortion. The methods of solving the transport equation can be applied to the scattering of radio waves, laser pulses, and other radiation propagating in random media.