Electron kinetic effects in back-stimulated Raman scattering bursts driven by broadband laser pulses

Abstract

We examine electron kinetic effects in broadband-laser-driven back-stimulated Raman scattering (BSRS) bursts using particle-in-cell simulations. These bursts occur during the nonlinear stage, causing reflectivity spikes and generating large numbers of hot electrons. Long-duration simulations are performed to observe burst events, and a simplified model is developed to eliminate the interference of the broadband laser’s random intensity fluctuations. Using the simplified model, we isolate and characterize the spectrum of electron plasma waves. The spectrum changes from a sideband structure to a turbulence-like structure during the burst. A significant asymmetry in the spectrum is observed. This asymmetry is amplified and transferred to electron phase space by high-intensity broadband laser pulses, leading to violent vortex-merging and generation of hot electrons. The proportion of hot electrons increases from 6.76% to 14.7% during a single violent burst event. We demonstrate that kinetic effects profoundly influence the BSRS evolution driven by broadband lasers.

Kinetic effects on the interaction of counter-propagating plasma shocks inside an ICF hohlraum

“…In hohlraums, kinetic effects are widespread. For electrons there is stimulated Raman scattering and stimulated Brillouin scattering [13,14]. For ions, double-humped ion distributions are found in the low-Z plasma when it becomes less collisional [15][16][17][18], which suggests that the kinetic phenomena need to be taken into account in low-density low-Z plasmas.…”