Experimental observation of backscattered light based on different coherence between incident laser beams

Xiangfu Meng,Guo Jia,Sizu Fu,Huazhen Zhou,Chen Wang,Honghai An

doi:10.1017/hpl.2013.11

Xiangfu Meng, Guo Jia + Show 4 more

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https://doi.org/10.1017/hpl.2013.11

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Abstract

AbstractRecent experimental results on NIF revealed a much higher stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) backscatter than expected; one possible reason was due to the coherence between incident laser beams. In our research, two laser beams (${\sim }1~\mathrm{ns} $, ${\sim }250~\mathrm{J} , 527~\mathrm{nm} $ in each one) with different coherent degrees between them from the SG-II facility were employed to irradiate an Au plate target; the backscatter of SBS and SRS in the range of the given solid angle had been measured. The results showed that it could change dramatically corresponding to the difference of the coherent degree between the two laser beams, and there was usually more intense backscatter the higher the coherent degree between the incident beams.

Highlights

It is well known that stimulated Brillouin scattering (SBS) and stimulated Raman scattering SRS are two kinds of parametric instabilities in laser–plasma interaction (LPI) of inertial confinement fusion (ICF)[1], which will increase with the growth of laser power density[2,3,4,5]
A possible reason is that the interference between incident beams results in a spatial non-uniform distribution of the laser intensity, and induces the obvious growth of SBS and SRS
Based on above point of view, this paper represents the measurement results of the backscatter of SBS and SRS from an Au plate target irradiated by two laser beams from the SG-II facility, and they are respective to the illuminated conditions of different coherent degrees between the two incident laser beams

Summary

Introduction

It is well known that stimulated Brillouin scattering (SBS) and stimulated Raman scattering SRS are two kinds of parametric instabilities in laser–plasma interaction (LPI) of inertial confinement fusion (ICF)[1], which will increase with the growth of laser power density[2,3,4,5]. They will induce the loss of driving laser energy. Based on above point of view, this paper represents the measurement results of the backscatter of SBS and SRS from an Au plate target irradiated by two laser beams from the SG-II facility, and they are respective to the illuminated conditions of different coherent degrees between the two incident laser beams

Experimental condition and setup

Experimental results and analysis

Conclusion