Abstract and subjects
Nonlinear physics governing the kinetic behavior of stimulated Raman scattering (SRS) in multi-speckled laser beams has been identified in the trapping regime over a wide range of k lambda(D) values (here k is the wave number of the electron plasma waves and lambda(D) is the Debye length) in homogeneous and inhomogeneous plasmas. Hot electrons from intense speckles, both forward and side-loss hot electrons produced during SRS daughter electron plasma wave bowing and filamentation, seed and enhance the growth of SRS in neighboring speckles by reducing Landau damping. Trapping-enhanced speckle interaction through transport of hot electrons, backscatter, and sidescatter SRS light waves enable the system of speckles to self-organize and exhibit coherent, sub-ps SRS bursts with more than 100% instantaneous reflectivity, resulting in an SRS transverse coherence width much larger than a speckle width and a SRS spectrum that peaks outside the incident laser cone. SRS reflectivity is found to saturate above a threshold laser intensity at a level of reflectivity that depends on k lambda(D): higher k lambda(D) leads to lower SRS and the reflectivity scales as similar to(k lambda(D))(-4). As k lambda(D) and Landau damping increase, speckle interaction via sidescattered light and side-loss hot electrons decreases and the occurrence of self-organized events becomes infrequent, leading to the reduction of time-averaged SRS reflectivity. It is found that the inclusion of a moderately strong magnetic field in the laser direction can effectively control SRS by suppressing transverse speckle interaction via hot electron transport. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4774964]