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Title: ''Self-Smoothing of Laser Light in Plasmas''.

Abstract

The modification of the optical characteristics of a laser beam by a plasma is a key issue in laser-plasma coupling. it is critical to understand how this takes place, if we are ever to understand the interaction processes in the plasma corona as well as the coupling at super-high intensities--as when laser pulses approach Petawatt intensities. Interpreting and understanding parametric instabilities in laser-produced plasmas has been a problem of increasing complexity. Improvements in diagnostic capabilities in experimental studies, as well as refinements in the modeling (using different numerical techniques), are showing a complex scenario: strong interplay among instabilities, modification of the plasma conditions caused by the instabilities, and modification to the initial distribution of laser intensity inside the plasma. Of particular interest are stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS), instabilities which have been studied extensively during the past 20 years, both theoretically and experimentally. Until now, most studies--mainly driven by requirements associated with inertial confinement fusion (ICF)--have concentrated on backscattering instabilities. The role of forward instabilities has not received much attention, despite having the potentials for strongly modifying the overall laser-plasma interaction region. The objective of this project is to study numerically the nonlinear enhancement of large-angle,more » forward scattering of two identical laser beams propagating in a preformed plasma. it is known that filamentation instability and self-focusing are capable of modifying laser-beam geometry, altering the electromagnetic-field distribution and spectral properties. These instabilities, combined with forward SBS, apparently cause a plasma-induced smoothing (self-smoothing) of the laser light as it propagates through the plasma. The final effect may have consequences similar to the temporal smoothing introduced intentionally in many laser systems. They do not propose this phenomenon as a smoothing technique; however, they claim that the understanding of this effect is crucial to the interpretation of experimental results on parametric instabilities.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab., CA (US)
Sponsoring Org.:
USDOE Office of Defense Programs (DP) (US)
OSTI Identifier:
792259
Report Number(s):
UCRL-ID-135918
TRN: US0300488
DOE Contract Number:  
W-7405-Eng-48
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 22 Feb 2000
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BACKSCATTERING; BRILLOUIN EFFECT; DISTRIBUTION; GEOMETRY; INERTIAL CONFINEMENT; INSTABILITY; LASER-PRODUCED PLASMA; LASERS; MODIFICATIONS; PARAMETRIC INSTABILITIES; PLASMA; SCATTERING

Citation Formats

Baldis, H A, Rozmus, W, Labaune, C, Cohen, B, and Bergen, R. ''Self-Smoothing of Laser Light in Plasmas''.. United States: N. p., 2000. Web. doi:10.2172/792259.
Baldis, H A, Rozmus, W, Labaune, C, Cohen, B, & Bergen, R. ''Self-Smoothing of Laser Light in Plasmas''.. United States. doi:10.2172/792259.
Baldis, H A, Rozmus, W, Labaune, C, Cohen, B, and Bergen, R. Tue . "''Self-Smoothing of Laser Light in Plasmas''.". United States. doi:10.2172/792259. https://www.osti.gov/servlets/purl/792259.
@article{osti_792259,
title = {''Self-Smoothing of Laser Light in Plasmas''.},
author = {Baldis, H A and Rozmus, W and Labaune, C and Cohen, B and Bergen, R},
abstractNote = {The modification of the optical characteristics of a laser beam by a plasma is a key issue in laser-plasma coupling. it is critical to understand how this takes place, if we are ever to understand the interaction processes in the plasma corona as well as the coupling at super-high intensities--as when laser pulses approach Petawatt intensities. Interpreting and understanding parametric instabilities in laser-produced plasmas has been a problem of increasing complexity. Improvements in diagnostic capabilities in experimental studies, as well as refinements in the modeling (using different numerical techniques), are showing a complex scenario: strong interplay among instabilities, modification of the plasma conditions caused by the instabilities, and modification to the initial distribution of laser intensity inside the plasma. Of particular interest are stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS), instabilities which have been studied extensively during the past 20 years, both theoretically and experimentally. Until now, most studies--mainly driven by requirements associated with inertial confinement fusion (ICF)--have concentrated on backscattering instabilities. The role of forward instabilities has not received much attention, despite having the potentials for strongly modifying the overall laser-plasma interaction region. The objective of this project is to study numerically the nonlinear enhancement of large-angle, forward scattering of two identical laser beams propagating in a preformed plasma. it is known that filamentation instability and self-focusing are capable of modifying laser-beam geometry, altering the electromagnetic-field distribution and spectral properties. These instabilities, combined with forward SBS, apparently cause a plasma-induced smoothing (self-smoothing) of the laser light as it propagates through the plasma. The final effect may have consequences similar to the temporal smoothing introduced intentionally in many laser systems. They do not propose this phenomenon as a smoothing technique; however, they claim that the understanding of this effect is crucial to the interpretation of experimental results on parametric instabilities.},
doi = {10.2172/792259},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Feb 22 00:00:00 EST 2000},
month = {Tue Feb 22 00:00:00 EST 2000}
}

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