Stimulated Raman scattering mechanisms and scaling behavior in planar direct-drive experiments at the National Ignition Facility
- Univ. of Rochester, NY (United States). Lab. for Laser Energetics
- Univ. of Alberta, Edmonton, AB (Canada)
- Univ. of Rochester, NY (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL)
Stimulated Raman scattering (SRS) has been investigated comprehensively in planar-geometry experiments at the National Ignition Facility at conditions relevant to the corona of inertial con finement fusion (ICF) ignition-scale direct-drive targets. These experiments at measured electron temperatures of 4 to 5 keV, simulated density scale lengths Ln of 400 to 700 um, and laser intensities at the quarter-critical density of up to 1.5 x 1015 W/cm2 have determined SRS thresholds and the scaling behavior of SRS for various beam geometries. Several SRS mechanisms, including saturated absolute SRS near the quarter-critical density and additional SRS, including near-backscatter or sidescatter at lower densities, have been identi fied. Correlation of time-dependent SRS at densities ~0.15 to 0.21 of the critical density with hot-electron signatures, as well as the magnitudes of these signatures across different experiments, is observed. Additional modeling work is needed to de nitively identify the density region in which hot electrons are generated, and will guide SRS and hot-electron preheat mitigation strategies for direct-drive-ignition designs.
- Research Organization:
- Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- NA0003856; AC52-07NA27344; NA003856
- OSTI ID:
- 1772313
- Alternate ID(s):
- OSTI ID: 1608505; OSTI ID: 1608934
- Report Number(s):
- LLNL-JRNL-818279; 2019-322, 1557; 1028681; TRN: US2206952
- Journal Information:
- Physics of Plasmas, Vol. 27, Issue 4; ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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