Burst behavior due to the quasimode excited by stimulated Brillouin scattering in high-intensity laser–plasma interactions

Q S Feng,Z J Liu,C Y Zheng,L H Cao,X T He

doi:10.1017/hpl.2019.44

Abstract

The strong-coupling mode, called the “quasimode”, is excited by stimulated Brillouin scattering (SBS) in high-intensity laser–plasma interactions. Also SBS of the quasimode competes with SBS of the fast mode (or slow mode) in multi-ion species plasmas, thus leading to a low-frequency burst behavior of SBS reflectivity. Competition between the quasimode and the ion-acoustic wave (IAW) is an important saturation mechanism of SBS in high-intensity laser–plasma interactions. These results give a clear explanation of the low-frequency periodic burst behavior of SBS and should be considered as a saturation mechanism of SBS in high-intensity laser–plasma interactions.

Highlights

Backward stimulated Brillouin scattering (SBS), a threewave interaction process where an incident electromagnetic wave (EMW) decays into a backscattered EMW and a forward propagating ion-acoustic wave (IAW), leads to a great energy loss of the incident laser and is detrimental in inertial confinement fusion (ICF)[1,2,3]
We report the first demonstration that the strong-coupling mode or quasimode is excited by SBS and coexists and competes with the IAW in high-intensity laser– plasma interactions
IAW mode and the quasimode, are excited in SBS in our simulation conditions, other modes such as the slow IAW mode and the ion bulk (IBk) mode[31] could be excited in SBS in some conditions, and the competition among SBS

Summary

Introduction

Backward stimulated Brillouin scattering (SBS), a threewave interaction process where an incident electromagnetic wave (EMW) decays into a backscattered EMW and a forward propagating ion-acoustic wave (IAW), leads to a great energy loss of the incident laser and is detrimental in inertial confinement fusion (ICF)[1,2,3]. In hybrid-drive ICF, the laser intensity can reach as high as I0 ∼ 1016 W/cm, and strong-coupling modes are excited by SBS. Andreev et al.[8] found that the interaction process of short light pulse amplification took place in the strongcoupling regime and that Brillouin scattering in the strongcoupling regime was a very promising candidate for the amplification of short laser pulses to high intensities over very short plasma lengths. We report the first demonstration that the strong-coupling mode or quasimode is excited by SBS and coexists and competes with the IAW in high-intensity laser– plasma interactions. Competition between the quasimode and the IAW excited by SBS is an important saturation mechanism of SBS in high-intensity laser–plasma interactions

Theoretical analysis

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Numerical simulation

Summary