INTERACTION OF 2 NEIGHBORING LASER-BEAMS TAKING INTO ACCOUNT THE EFFECTS OF PLASMA HYDRODYNAMICS

The interaction between two neighboring laser beams focused in a hot u nderdense homogeneous plasma is investigated using the non-paraxial wa ve coupling code KOLIBRI [S. Huller er al., Phys. Scr. T63, 151 (1996) ] in two and three spatial dimensions. Both the plasma hydrodynamic ev olution and the stimulated Brillouin scattering (SBS) aspects are stud ied in the case of strongly damped ion sound waves. The hydrodynamic e ffects consist in ponderomotively driven density perturbations located between the beams which may, in turn, influence strongly the light pr opagation through the plasma. The two beams are found to merge wheneve r the distance between them is smaller than or of the order of their d iameter. Concerning the SBS aspect, it is found that due to interferen ce effects between the beams, the spatial amplification of the backsca ttered light is asymmetric with respect to the laser axis. SBS can als o enforce the hydrodynamic effects and the beam merging. (C) 1997 Amer ican Institute of Physics.