Stimulated scattering and filamentation of laser radiation in a plasma

A state of the art review is given of experimental and theoretical investigations of nonlinear processes that appear when laser radiation acts on a plasma and solid targets. It is shown that the absorption coefficient of laser radiation and the absorption quality improve greatly when submicron wavelengths are used. However, an increase in the ratio of the plasma corona thickness to the radiation wavelength enhances the role of stimulated Brillouin scattering, filamentation, self-focusing, and stimulated Raman scattering. Experimental results of studies of stimulated Brillouin and Raman scattering, of self-focusing, and filamentation of laser radiation in a plasma demonstrate that these processes should play an important role under conditions typical of pulsed thermonuclear reactions characterized by a positive yield. The experimental results also show that the stimulated scattering and filamentation in a laser plasma are related and mutually interdependent: filamentation lowers the stimulated Brillouin scattering threshold, whereas such scattering prevents the growth of stimulated Raman scattering, and so on. Observations which can be explained theoretically are pointed out. Future trends in the theory are discussed and methods for controlling nonlinear interaction of waves in a laser plasma are considered.