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arXiv · 2209.08251

Measurement of Stimulated Raman Side-Scattering Predominance in Directly Driven Experiment

Kevin Glize·Xu Zhao·Yihang Zhang·Changwang Lian·Shang Tan·Fuyuan Wu·Chengzhuo Xiao·Rui Yan·Zhe Zhang·Xiaohui Yuan·Jie Zhang
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Abstract

Due to its particular geometry, stimulated Raman side-scattering (SRSS) drives scattered light emission at non-conventional directions, leading to scarce and complex experimental observations. Direct-irradiation campaigns at the SG-II UP facility have measured the scattered light driven by SRSS over a wide range of angles. It indicated an emission at large polar angles over a broad azimuthal range, sensitive to the plasma profile and laser polarization, resulting in a loss of about 5\% of the total laser energy. Direct comparison with back-scattering measurement has evidenced SRSS as the dominant Raman scattering process. The predominance of SRSS was confirmed by 2D particle-in-cell simulations, and its angular spread has been corroborated by ray-tracing simulations. The main implication is that a complete characterization of the SRS instability and an accurate measurement of the energy losses require the collection of the scattered light in a broad range of directions. Otherwise, spatially limited measurement could lead to an underestimation of the energetic importance of stimulated Raman scattering.

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Kevin Glize, Xu Zhao, Yihang Zhang, Changwang Lian, Shang Tan, Fuyuan Wu, Chengzhuo Xiao, Rui Yan, Zhe Zhang, Xiaohui Yuan, Jie Zhang. 2022-09-17. Measurement of Stimulated Raman Side-Scattering Predominance in Directly Driven Experiment. https://doi.org/10.1063/5.0180607

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