Collisionless damping of localized plasma waves in laser-produced plasmas and application to stimulated Raman scattering in filaments
- Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York, 14623-1299 (United States)
Observations of stimulated Raman scattering (SRS) in laser-produced plasmas often yield results at odds with theoretical predictions. For example, SRS is commonly seen at incident laser intensities below the theoretical threshold, and the spectrum of SRS light often extends to much shorter wavelengths than models predict. To account for these anomalies it is often proposed that SRS is occurring in high-intensity, self-focused light filaments. A serious problem with this model is that plasma wave damping rates estimated on the basis of the usual Landau theory for homogeneous plasmas would seem to rule out this explanation for many cases of interest. Damping rates for plasma waves confined to small-radius filaments, however, could be significantly different than damping rates for plane waves. Using a novel method for calculating transit-time damping, this paper analyzes the collisionless damping of plasma waveguide modes in a cylinder. It is found that the actual damping rates for waveguide modes in a suitable filament model are much less than for the plane waves in a homogeneous plasma producing the same wavelength of SRS emission. Consequently, the filament model remains viable as an explanation of the anomalous SRS observations. {copyright} {ital 1998 American Institute of Physics.}
- OSTI ID:
- 300088
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 12 Vol. 5; ISSN PHPAEN; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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