The Multiple-Beam Two-Plasmon-Decay Instability

Recent developments in experimental techniques and simulations have led to an improved understanding of the nonlinear evolution of the two-plasmon-decay (TPD) instability relevant to direct-drive inertial confinement fusion (ICF). Experiments on the OMEGA laser used ultraviolet Thomson scattering to observe TPD electron plasma waves driven by multiple laser beams in a variety of experimental configurations. The experiments were modeled in 3-D using a hybrid code (LPSE) that combines a pseudospectral wave solver with a particle tracker to self-consistently calculate Landau damping. Thomson-scattering measurements of several different plasma wavevectors show a highly anisotropic turbulent TPD driven electron-plasma-wave spectrum and are well reproduced by LPSE simulations. Direct comparison between simulated and measured hot-electron spectra indicate that the hybrid-particle model correctly captures the hot-electron generation mechanism associated with the nonlinear evolution of the TPD instability.