Multiple scattering by dense random media: Volume-element extinction

We consider multiple scattering of electromagnetic waves in dense discrete random media of particles. Here we focus on the exact computation of the coherent and incoherent scattered far fields for finite volume elements of spherical particles. We solve the scattering problem with the Superposition T-matrix method. We derive the incoherent extinction coefficient and, subsequently, the extinction mean-free-path length for volume elements with varying numbers of spherical particles as well as varying volume fractions of particles. In addition to confirming known results for incoherent scattering, we show new results, in particular, for the polarization effects in incoherent scattering.