LASER-PLASMA FILAMENTATION AND THE SPATIALLY PERIODIC NONLINEAR SCHRODINGER-EQUATION APPROXIMATION

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