Thermal effects on coupled self-focusing and Raman scattering of a laser in a self-consistent plasma channel

Journal Article · Tue Aug 01 04:00:00 EDT 1995 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.871143· OSTI ID:76483

Liu, C S; Tripathi, V K ^[1]

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1. Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)

A self-ducted Gaussian laser beam, propagating through a plasma, is unstable to a perturbation in its spot size, {ital r}{sub 0}. A reduction (or enhancement) in {ital r}{sub 0} leads to an enhancement (or reduction) in axial intensity, translating {ital r}{sub 0} modulation into intensity variation with axial distance and time, causing ponderomotive force on the electrons that drive a Langmuir wave. The density troughs/crests of the Langmuir wave, moving with the group velocity of the laser, cause self-focusing/defocusing of the laser, enhancing the original perturbation and leading to a combined instability of self-focusing, and Raman scattering of the laser beam. The thermal effects allow the Langmuir wave to be treated as a radially localized eigenmode with finite group velocity in the axial direction. The spatial growth rate of the instability decreases with electron temperature while it increases with plasma density. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

• DOE Contract Number: FG02-87ER53257
• OSTI ID: 76483
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 8 Vol. 2; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BEAM-PLASMA SYSTEMS
INSTABILITY GROWTH RATES
LASER RADIATION
LASER-PRODUCED PLASMA
RAMAN EFFECT
RELATIVISTIC PLASMA