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  • 1
    Electronic Resource
    Electronic Resource
    Stimulated Raman scattering in inhomogeneous collisional laser-produced plasmas (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 1 (1994), S. 993-1007 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Convective gain and absolute growth of stimulated Raman scattering (SRS) are determined for a hot inhomogeneous collisional plasma using an integrated global model that includes the effects of wave propagation and both collisional and Landau damping in a density ramp. This unifies the time asymptotic theory of SRS occurring near the quarter-critical density of the laser light and that occurring at lower densities. The level of collisions has a striking effect on the convective behavior of the instability. When collisions are weak, no significant regime of convective gain exists. In consequence, absolute resonances are very sensitive and susceptible to detuning, particularly so near the quarter-critical density. This is shown to be a key factor in understanding the Raman "gap'' seen in experiments. No such gap appears in highly collisional regimes in which the absolute resonances are insensitive and significant convective gain occurs over the whole range of wavelengths.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870758
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  • 2
    Electronic Resource
    Electronic Resource
    Studies of stimulated Raman scattering in a plasma filament (1988)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 31 (1988), S. 641-650 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of a plasma filament on the characteristics of stimulated Raman scattering is examined. The model representation of the filament allows an assessment of the way in which Raman growth rates are influenced not only by the density inhomogeneity transverse to the beam direction, but by the nonuniform intensities of the incident laser and scattered light, as well as by Landau damping in the plasma. The model determines global eigenvalues without recourse to local (WKB) approximations, or to phenomenological damping factors. In shallow filaments the concentration of the light gives rise to modest gains in growth, while for deeper filaments the effects of the inhomogeneity and of Landau damping are dominant and suppress the instability. In both cases the strongest growth occurs at the bottom of the filament. Waveguide effects in deep filaments can result in emission being constrained to wavelengths significantly shorter than twice that of the incident laser light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866794
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  • 3
    Electronic Resource
    Electronic Resource
    Morphology of magnetic fields generated in laser-produced plasmas (1988)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 31 (1988), S. 651-657 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetic fields in the megagauss range have been measured in experiments on plasmas generated by irradiating targets with high power lasers. A study of the morphology of these self-generated fields is important not only for its intrinsic interest but for possible implications in laser–target physics. In this paper work on the numerical modeling of large magnetic fields generated in target experiments is reported. The results show generally satisfactory agreement with the fields measured experimentally both in terms of the magnitude of the peak fields and their morphology. In the numerical model the contribution from the Hall term in describing the evolution of the magnetic field is shown to be important especially in short pulse ((approximately-equal-to)100 psec) experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866795
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetic theory of stimulated Raman sidescattering from magnetized plasmas (1985)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 28 (1985), S. 3380-3386 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A theory of stimulated Raman sidescattering in magnetized plasmas is presented based on a solution of the Vlasov–Maxwell equations. The incident laser light, in the form of extraordinary mode radiation, decays into light waves which propagate along the uniform magnetic field as right or left circularly polarized waves. The scattered plasma mode is an obliquely propagating electron-Bernstein wave. The possible relevance of the theory to experiments in which structure is observed in radiation at one-half of the laser frequency is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.865337
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  • 5
    Electronic Resource
    Electronic Resource
    Stimulated Raman scattering from a density maximum in a laser-produced plasma (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 1151-1153 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thresholds and growth rates for stimulated Raman scattering from a plasma density maximum, corresponding to laser–target burnthrough experiments, are obtained by numerical solution of the full-wave Raman scattering equations. This supplements and extends to new regimes the WKB analysis of Rosenbluth [Phys. Rev. Lett. 29, 565 (1972)] and the quasiglobal analysis of Williams and Johnston [Phys. Fluids B 1, 188 (1989)]. The results show unexpected scalings with laser intensity well above threshold, and permit absolutely unstable forward scattering with thresholds comparable to those for backward scattering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.858990
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  • 6
    Electronic Resource
    Electronic Resource
    Stimulated Raman scattering from density cavities in laser-produced plasmas (1992)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 2942-2952 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The occurrence of stimulated Raman scattering from within localized density cavities that may be present in many laser-produced plasmas is studied. Then scattering in both the backward and forward directions from a single cavity becomes absolutely unstable, with a common growth rate and zero inhomogeneous plasma thresholds whenever electron plasma waves are totally trapped within the cavity. Both back- and forward scattering mechanisms contribute to this common growth rate. A cavity therefore equalizes the growth of emission in backward and forward directions. Forward scattering in its own right gives rise to absolute growth. The threshold for absolute growth is then set by damping, and by Landau damping of the plasma wave in particular. Only very modest density depressions are needed to trap the long-wavelength weakly damped plasma waves. Absolutely unstable back- and forward scattering from within shallow cavities in the underdense coronal plasmas of laser fusion targets may prove to be commonplace rather than the exception, although growth rates are generally slow and sensitive to the cavity density and scale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860134
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  • 7
    Electronic Resource
    Electronic Resource
    Filamentation in a magnetized plasma (1987)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 30 (1987), S. 533-538 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Filamentation has been examined in laser-produced plasmas in which magnetic fields are present, using a two-fluid model of the plasma. Configurations in which the low-frequency perturbation is in turn parallel and perpendicular to the magnetic field have been considered and the instability examined in the two cases. In the latter it is shown that the instability is quenched by large enough fields, while for the ion-acoustic perturbation the behavior is more complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866350
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  • 8
    Electronic Resource
    Electronic Resource
    Finite Larmor radius effects in stimulated Raman scattering (1985)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 28 (1985), S. 1193-1195 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Stimulated Raman scattering from a magnetized plasma has been examined using the set of Vlasov–Maxwell equations. The incident laser light, propagating in the form of an extraordinary mode, decays into a scattered extraordinary mode together with electron-Bernstein waves. For sufficiently strong magnetic fields and high electron temperatures, the growth rates of these waves become comparable to the field-free values. At relatively low plasma densities the magnetic field can result in scattered light at ω0/2 (where ω0 is the laser frequency), a frequency associated with radiation emitted from the quarter-critical density region of unmagnetized plasmas. We have compared the results from the kinetic theory analysis with observations from numerical experiments using a 1 1/2 -D electromagnetic particle code and found them to be in good agreement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.864994
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  • 9
    Electronic Resource
    Electronic Resource
    Inverse resonance absorption in an inhomogeneous magnetized plasma (1985)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 28 (1985), S. 16-18 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The linear mode conversion of a plasma wave to a light wave in a magnetized plasma has been examined theoretically and by computer simulation. This conversion is the inverse of resonance absorption exhibiting an identical dependence on magnetic field and density scale length with an optimum conversion efficiency of approximately 60%. Radiation from this source may contribute to the harmonic spectra observed from laser-irradiated plasmas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.865177
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  • 10
    Electronic Resource
    Electronic Resource
    Radiation losses due to discontinuities in asymmetric three-layer optical waveguides (1980)
    Springer
    Optical and quantum electronics 12 (1980), S. 143-158 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract In this paper, the radiation losses caused by film thickness and refractive index discontinuities in asymmetric slab waveguides are examined theoretically. A technique developed by Mahmoud and Beal for dealing with the continuous part of the radiation spectrum is used. Several numerical examples which show the radiation loss for various waveguide configurations are presented and discussed and, where appropriate, comparisons with other related work made. In the case of asymmetric thickness steps, the radiation losses are found to be appreciably higher than those computed for symmetric guides. The radiation losses for guides having the same thickness were found to decrease as the guide thickness increased. Once the TE1 mode become guided, the losses decreased rapidly. However, if the two guides had different thickness then it was found that the losses exhibited a minimum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00619558
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