Coherent Nonlinear Backscattering by Laser-Plasma Interactions

Abstract

A theoretical analysis is carried out for the problem of coherent nonlinear backscattering of laser radiation by a high density plasma. A number of effects of direct interest to the DT-pellet fusion research are investigated. A simple physical description is introduced, which relies on a nonlinear potential formulation of the scattering equations. The simplicity and the unified nature of the approach enables us to evaluate and compare the influence on the radiation reflectivity of different effects, such as e.g. inhomogeneities, blow-off velocities, temperature gradients, laser band width and relativistic oscillatory velocities. Our understanding of the role played by the various phenomena has consequently improved and we think that our approach should be useful for the interpretation of laser-plasma data obtained by computer simulation or laboratory experiments. The results may also be utilized to estimate how and to what extent one may avoid undesired anomalous reflection when planning new laser-plasma devices.