skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Observation of forward Raman scattering enhanced by backward Raman scattering in a laser plasma

Abstract

The coupling between backward and forward Raman scattering was studied experimentally in a preformed underdense parabolic shaped plasma irradiated with a CO/sub 2/ laser. The forward and backward Raman spectra were simultaneously recorded, and together with interferometry indicated that stimulated Raman scattering was occurring at the top of the profile. The forward Raman was observed well below its parabolic threshold, and it is proposed that plasma waves from backward Raman scattering act as an enhanced noise source for the forward Raman process. A model, whereby the forward and backward Raman processes are coupled together to produce an absolute instability, based on the Koch and Williams coupled Raman model (Phys. Fluids 27, 2346 (1984)), is shown to explain many of the observed features. This is shown to be very similar to a model of two backward Raman amplifiers displaced from the top of the plasma profile.

Authors:
;
Publication Date:
Research Org.:
Division of Physics, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
OSTI Identifier:
5153272
Resource Type:
Journal Article
Journal Name:
Phys. Fluids; (United States)
Additional Journal Information:
Journal Volume: 31:6
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; LASER-PRODUCED PLASMA; RAMAN EFFECT; BACKSCATTERING; CARBON DIOXIDE LASERS; COHERENT SCATTERING; COUPLING; INTERFEROMETRY; MATHEMATICAL MODELS; SHAPE; GAS LASERS; LASERS; PLASMA; SCATTERING; 700108* - Fusion Energy- Plasma Research- Wave Phenomena

Citation Formats

Villeneuve, D M, and Baldis, H A. Observation of forward Raman scattering enhanced by backward Raman scattering in a laser plasma. United States: N. p., 1988. Web. doi:10.1063/1.866668.
Villeneuve, D M, & Baldis, H A. Observation of forward Raman scattering enhanced by backward Raman scattering in a laser plasma. United States. https://doi.org/10.1063/1.866668
Villeneuve, D M, and Baldis, H A. Wed . "Observation of forward Raman scattering enhanced by backward Raman scattering in a laser plasma". United States. https://doi.org/10.1063/1.866668.
@article{osti_5153272,
title = {Observation of forward Raman scattering enhanced by backward Raman scattering in a laser plasma},
author = {Villeneuve, D M and Baldis, H A},
abstractNote = {The coupling between backward and forward Raman scattering was studied experimentally in a preformed underdense parabolic shaped plasma irradiated with a CO/sub 2/ laser. The forward and backward Raman spectra were simultaneously recorded, and together with interferometry indicated that stimulated Raman scattering was occurring at the top of the profile. The forward Raman was observed well below its parabolic threshold, and it is proposed that plasma waves from backward Raman scattering act as an enhanced noise source for the forward Raman process. A model, whereby the forward and backward Raman processes are coupled together to produce an absolute instability, based on the Koch and Williams coupled Raman model (Phys. Fluids 27, 2346 (1984)), is shown to explain many of the observed features. This is shown to be very similar to a model of two backward Raman amplifiers displaced from the top of the plasma profile.},
doi = {10.1063/1.866668},
url = {https://www.osti.gov/biblio/5153272}, journal = {Phys. Fluids; (United States)},
number = ,
volume = 31:6,
place = {United States},
year = {1988},
month = {6}
}