Three-dimensional particle-in-cell modeling of parametric instabilities near the quarter-critical density in plasmas

The nonlinear regime of laser-plasma interaction including both two-plasmon--decay (TPD) and stimulated Raman scattering (SRS) instabilities has been studied in three-dimensional (3-D) particle-in-cell simulations with parameters relevant to the inertial confinement fusion (ICF) experiments. SRS and TPD develop in the same region in plasmas, and the generation of fast electrons can be described accurately with only the full model including both SRS and TPD. The growth of instabilities in the linear stage is found to be in good agreement with analytical theories. In the saturation stage the enhanced low-frequency density perturbations driven by the daughter waves of the SRS sidescattering can saturate the TPD and consequently inhibit the fast-electron generation. The fast-electron flux in 3-D modeling is up to an order of magnitude smaller than previously reported in 2-D TPD simulations, bringing it close to the results of ICF experiments.