Investigation of ruling parameters on the growth of side and back stimulated Raman scattering in inhomogeneous plasmas at shock ignition laser intensity

Recent experiments at the National Ignition Facility and theoretical modeling suggest that side stimulated Raman scattering (SSRS) instability could reduce laser–plasma coupling and generate considerable fluxes of suprathermal hot electrons under interaction conditions envisaged for direct-drive schemes for inertial confinement fusion. Nonetheless, SSRS remains to date one of the least understood parametric instabilities. Here, we report the first angularly and spectrally resolved measurements of scattered light at laser intensities relevant for the shock ignition scheme (I ∼ 1016 W/cm2), showing significant SSRS growth in the direction perpendicular to the laser polarization. Modification of the focal spot shape and orientation, obtained by using two different random phase plates, and of the density gradient of the plasma, by utilizing exploding foil targets of different thicknesses, clearly reveals a different dependence of backward SRS (BSRS) and SSRS on experimental parameters. While convective BSRS scales with plasma density scale length, as expected by linear theory, the growth of SSRS depends on the spot extension in the direction perpendicular to laser polarization. Our analysis therefore demonstrates that under current experimental conditions, with density scale lengths Ln ≈ 60–120 μm and spot sizes FWHM ≈ 40–100 μm, SSRS is limited by laser beam size rather than by the density scale length of the plasma.

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Publication Details

Journal
Matter and Radiation at Extremes
Published
2025-07-01
DOI
https://doi.org/10.1063/5.0257022
Citations
2
Primary Topic
Laser-induced spectroscopy and plasma
Type
article
Field-Weighted Citation Impact
1.73

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article

Investigation of ruling parameters on the growth of side and back stimulated Raman scattering in inhomogeneous plasmas at shock ignition laser intensity

Xiaohui Yuan, S. K. Singh, P. Koester, A. Morace et al.
2 citations
Matter and Radiation at Extremes
Laser-induced spectroscopy and plasma
1.73
article

Investigation of ruling parameters on the growth of side and back stimulated Raman scattering in inhomogeneous plasmas at shock ignition laser intensity

Xiaohui Yuan, S. K. Singh, P. Koester, A. Morace, Xu Zhao, O. Renner, Jie Zhang, Ph. Nicolaï, Shubham Agarwal, P Gajdoš, M. Tatarakis, D. Batani, E. Hume, M. Krupka, N. C. Woolsey, L. Juha, M. Krůs, D. Mancelli, H. Larreur, L. A. Gizzi, K. Glize, Šimon Jelínek, G. Malka, P. E. Masson-Laborde, G. Cristoforetti, Michal Cervenak, David Ettel, R. Dudžák, D. Singappuli, Yixin Wang, P. Devi
article en
2 citations

Abstract

Recent experiments at the National Ignition Facility and theoretical modeling suggest that side stimulated Raman scattering (SSRS) instability could reduce laser–plasma coupling and generate considerable fluxes of suprathermal hot electrons under interaction conditions envisaged for direct-drive schemes for inertial confinement fusion. Nonetheless, SSRS remains to date one of the least understood parametric instabilities. Here, we report the first angularly and spectrally resolved measurements of scattered light at laser intensities relevant for the shock ignition scheme (I ∼ 1016 W/cm2), showing significant SSRS growth in the direction perpendicular to the laser polarization. Modification of the focal spot shape and orientation, obtained by using two different random phase plates, and of the density gradient of the plasma, by utilizing exploding foil targets of different thicknesses, clearly reveals a different dependence of backward SRS (BSRS) and SSRS on experimental parameters. While convective BSRS scales with plasma density scale length, as expected by linear theory, the growth of SSRS depends on the spot extension in the direction perpendicular to laser polarization. Our analysis therefore demonstrates that under current experimental conditions, with density scale lengths Ln ≈ 60–120 μm and spot sizes FWHM ≈ 40–100 μm, SSRS is limited by laser beam size rather than by the density scale length of the plasma.

Matter and Radiation at ExtremesVol. 10(4)
Istituto di Scienza e Tecnologie dell'Informazione "Alessandro Faedo" (IT), Rutherford Appleton Laboratory (GB), Centre National de la Recherche Scientifique (FR), Technical University of Liberec (CZ), Université de Bordeaux (FR), Universidad de Salamanca (ES), Charles University (CZ), Mediterranean University (ME), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Université Paris-Saclay (FR), Hellenic Mediterranean University (GR), Extreme Light Infrastructure Beamlines (CZ), CEA DAM Île-de-France (FR), Czech Academy of Sciences, Institute of Plasma Physics (CZ), Centre Lasers Intenses et Applications (FR), FZU ‒ Institute of Physics of the Academy of Sciences of the Czech Republic (CZ), CEA Paris-Saclay (FR), Czech Technical University in Prague (CZ), University of York (GB)
Laserlab-Europe, EUROfusion
Openalex Percentile: Top 16%
Laser-induced spectroscopy and plasma
1.73
DOIOpen Access PDFOpenAlex
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