Laser-plasma filamentation and the spatially periodic nonlinear Schrodinger equation approximation

For understanding self-focusing and filamentation of electromagnetic beams in plasmas (and other media) when the beam power is well over critical, considerable success has recently been achieved using the well-known nonlinear Schrodinger equation with saturating nonlinearities. Sufficiently large isolated high-power beams with noticeable structure can break up into numerous filaments, which emerge from the phase of filament creation rather close to the known filament equilibria having lost excess power while forming and pulsating. However, the periodic boundary cases more characteristic of laser beam coverage of inertial confinement fusion targets show asymptotic states more complicated than a noninteracting ensemble of equilibrium filaments. While the filament density can be estimated in terms of the average intensity, considerable filament interaction and activity is the usual result. At extremely high intensities very complicated self-focusing structures are formed. (C) 1997 American Institute of Physics.