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Title: Modeling the Backscatter and Transmitted Light of High Power Smoothed Beams with pF3D, a Massively Parallel Laser Plasma Interaction Code

Abstract

Using the three-dimensional wave propagation code, F3D[Berger et al., Phys. Fluids B 5,2243 (1993), Berger et al., Phys. Plasmas 5,4337(1998)], and the massively parallel version pF3D, [Still et al. Phys. Plasmas 7 (2000)], we have computed the transmitted and reflected light for laser and plasma conditions in experiments that simulated ignition hohlraum conditions. The frequency spectrum and the wavenumber spectrum of the transmitted light are calculated and used to identify the relative contributions of stimulated forward Brillouin and self-focusing in hydrocarbon-filled balloons, commonly called gasbags. The effect of beam smoothing, smoothing by spectral dispersion (SSD) and polarization smoothing (PS), on the stimulated Brillouin backscatter (SBS) from Scale-1 NOVA hohlraums was simulated with the use nonlinear saturation models that limit the amplitude of the driven acoustic waves. Other experiments on CO{sub 2} gasbags simultaneously measure at a range of intensities the SBS reflectivity and the Thomson scatter from the SBS-driven acoustic waves that provide a more detailed test of the modeling. These calculations also predict that the backscattered light will be very nonuniform in the nearfield (the focusing system optics) which is important for specifying the backscatter intensities be tolerated by the National Ignition Facility laser system.

Authors:
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Publication Date:
Research Org.:
Lawrence Livermore National Lab., CA (US)
Sponsoring Org.:
USDOE Office of Defense Programs (DP) (US)
OSTI Identifier:
793610
Report Number(s):
UCRL-JC-137900
Journal ID: ISSN 0277-786X; TRN: US0205248
DOE Contract Number:  
W-7405-Eng-48
Resource Type:
Conference
Resource Relation:
Journal Volume: 4424; Conference: 26th European Conference on Laser Interaction with Matter, Prague (CZ), 06/12/2000--06/16/2000; Other Information: PBD: 1 Jun 2000
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ACOUSTICS; AMPLITUDES; FOCUSING; IGNITION; LASERS; OPTICS; PLASMA; POLARIZATION; REFLECTIVITY; SATURATION; US NATIONAL IGNITION FACILITY; WAVE PROPAGATION

Citation Formats

Berger, R L, Divol, L, Glenzer, S, Hinkel, D E, Kirkwood, R K, Langdon, A B, Moody, J D, Still, C H, Suter, L, Williams, E A, and Young, P E. Modeling the Backscatter and Transmitted Light of High Power Smoothed Beams with pF3D, a Massively Parallel Laser Plasma Interaction Code. United States: N. p., 2000. Web. doi:10.1117/12.425594.
Berger, R L, Divol, L, Glenzer, S, Hinkel, D E, Kirkwood, R K, Langdon, A B, Moody, J D, Still, C H, Suter, L, Williams, E A, & Young, P E. Modeling the Backscatter and Transmitted Light of High Power Smoothed Beams with pF3D, a Massively Parallel Laser Plasma Interaction Code. United States. doi:10.1117/12.425594.
Berger, R L, Divol, L, Glenzer, S, Hinkel, D E, Kirkwood, R K, Langdon, A B, Moody, J D, Still, C H, Suter, L, Williams, E A, and Young, P E. Thu . "Modeling the Backscatter and Transmitted Light of High Power Smoothed Beams with pF3D, a Massively Parallel Laser Plasma Interaction Code". United States. doi:10.1117/12.425594. https://www.osti.gov/servlets/purl/793610.
@article{osti_793610,
title = {Modeling the Backscatter and Transmitted Light of High Power Smoothed Beams with pF3D, a Massively Parallel Laser Plasma Interaction Code},
author = {Berger, R L and Divol, L and Glenzer, S and Hinkel, D E and Kirkwood, R K and Langdon, A B and Moody, J D and Still, C H and Suter, L and Williams, E A and Young, P E},
abstractNote = {Using the three-dimensional wave propagation code, F3D[Berger et al., Phys. Fluids B 5,2243 (1993), Berger et al., Phys. Plasmas 5,4337(1998)], and the massively parallel version pF3D, [Still et al. Phys. Plasmas 7 (2000)], we have computed the transmitted and reflected light for laser and plasma conditions in experiments that simulated ignition hohlraum conditions. The frequency spectrum and the wavenumber spectrum of the transmitted light are calculated and used to identify the relative contributions of stimulated forward Brillouin and self-focusing in hydrocarbon-filled balloons, commonly called gasbags. The effect of beam smoothing, smoothing by spectral dispersion (SSD) and polarization smoothing (PS), on the stimulated Brillouin backscatter (SBS) from Scale-1 NOVA hohlraums was simulated with the use nonlinear saturation models that limit the amplitude of the driven acoustic waves. Other experiments on CO{sub 2} gasbags simultaneously measure at a range of intensities the SBS reflectivity and the Thomson scatter from the SBS-driven acoustic waves that provide a more detailed test of the modeling. These calculations also predict that the backscattered light will be very nonuniform in the nearfield (the focusing system optics) which is important for specifying the backscatter intensities be tolerated by the National Ignition Facility laser system.},
doi = {10.1117/12.425594},
journal = {},
issn = {0277-786X},
number = ,
volume = 4424,
place = {United States},
year = {2000},
month = {6}
}

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