Effects of frequency-modulated pump on stimulated Brillouin scattering in inhomogeneous plasmas

Chen, Y; Zheng, C Y; Liu, Z J; Cao, L H; Xiao, C Z

doi:10.1088/1361-6587/ad02bd

Cited by 2 publications

(1 citation statement)

References 43 publications

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“…具体建模方法为在宽带激光电场前加入一个强度调制函数 , 该函数具有如下形式: 会引发某些低频不稳定性过程, 如SBS和CBET 等 . 在先前的工作中 , Albright等 [4] , Afeyan 和 Hüller [25,26] 宽带激光设计相结合, 如解耦光 [8] 、近太阳光 [18] 、弹簧光 [19] 等, 有望在更长时间、更大空间尺度上抑…”

Section: 使用简单的几何关系得到unclassified

Suppression of stimulated Raman scattering kinetic bursts by intensity-modulated broadband laser

Liu,

Zhang,

Cai

et al. 2024

Acta Phys. Sin.

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Laser plasma instability is one of the difficulties that plague inertial confinement fusion. As an effective tool for suppressing laser-plasma instabilities, broadband lasers have received a lot of attention in recent years. However, the nonlinear bursts of high-frequency instabilities, such as stimulated Raman scattering driven by broadband lasers in the kinetic regime, make the suppression effect less than expected. In this paper, a broadband laser model with intensity modulation is proposed. By choosing an appropriate intensity modulation envelope, it is possible to interrupt the amplification process of backscattered light in strong pulses, reduce the probability of high-intensity pulses inducing intense bursts, and drastically reduce the fraction of backscattered light and hot electron yield. Numerical simulations showed that the intensity-modulated laser has a good ability to suppress stimulated Raman scattering. For a broadband laser with an average power of 1.0 × 1015 W/cm2 and a bandwidth of 0.6%, the reflectivity decreases by an order of magnitude and the fraction of hot electron energy above 20 keV decreases from 7.34% to 0.31% using the intensity modulation technique. The above results confirm the feasibility of using the intensity-modulated broadband laser to suppress the high-frequency instability and are expected to provide a reference for the design of subsequent broadband laser-driven fusion experiments.

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Section: 使用简单的几何关系得到unclassified

Suppression of stimulated Raman scattering kinetic bursts by intensity-modulated broadband laser

Liu,

Zhang,

Cai

et al. 2024

Acta Phys. Sin.

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

Liu,

Deng,

Wang

et al. 2024

Matter and Radiation at Extremes

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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.

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Effects of frequency-modulated pump on stimulated Brillouin scattering in inhomogeneous plasmas

Cited by 2 publications

References 43 publications

Suppression of stimulated Raman scattering kinetic bursts by intensity-modulated broadband laser

Suppression of stimulated Raman scattering kinetic bursts by intensity-modulated broadband laser

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

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