Intermittent excitation of parametric instabilities enhanced by synergistic effect in broadband laser plasma interaction

TL;DR

This study investigates how broadband lasers induce intermittent parametric instabilities in plasma, revealing a synergistic effect that enhances hot electron production and affects instability suppression.

Contribution

It uncovers a new evolution pattern of parametric instabilities driven by broadband lasers, highlighting the role of high-intensity pulses and their synergistic effects in plasma interactions.

Findings

Intermittent excitation of parametric instabilities caused by high-intensity pulses.

Synergism reduces Landau damping, promoting transition to absolute instability.

Large laser bandwidths suppress parametric instabilities.

Abstract

A new evolution pattern for parametric instabilities in the non-linear stage driven by a broadband laser is studied with kinetic particle-in-cell simulations. It is found that an intermittent excitation of parametric instabilities caused by the high-intensity pulses, which are generated by the laser intensity variation of the broadband laser. The synergism between these high-intensity pulses reduces the Landau damping through the co-propagation of the electron-plasma waves and hot electrons, promoting the transition from convective to absolute stimulated Raman scattering. These intermittently excited parametric instabilities, especially absolute instability, will produce over-expected hot electrons compared with linear theory. However, comparisons between the energy of scattered lights for various bandwidth lasers indicate suppression of parametric instabilities with large laser bandwidths. Our works provided an opportunity to advance the understanding of the broadband laser-plasma interaction.