Showing papers by "Richard Berger published in 1999"
TL;DR: In this article, a spatio-temporal smoothing scheme was proposed to control filamentation and stimulated Raman and Brillouin scattering in laser fusion experiments, where the effect of smoothing must include the competition among all three instabilities.
Abstract: Control of filamentation and stimulated Raman and Brillouin scattering is shown to be possible by use of both spatial and temporal smoothing schemes. The spatial smoothing is accomplished by the use of phase plates [Y. Kato and K. Mima, Appl. Phys. 329, 186 (1982)] and polarization smoothing [Lefebvre et al., Phys. Plasmas 5, 2701 (1998)] in which the plasma is irradiated with two orthogonally polarized, uncorrelated speckle patterns. The temporal smoothing considered here is smoothing by spectral dispersion [Skupsky et al., J. Appl. Phys. 66, 3456 (1989)] in which the speckle pattern changes on the laser coherence time scale. At the high instability gains relevant to laser fusion experiments, the effect of smoothing must include the competition among all three instabilities.
32 citations
TL;DR: In this article, the authors observed the nonlinear saturation of Langmuir waves produced by a probe laser beam interacting with a high intensity pumping laser beam and showed that the wave is nonlinearly saturated consistent with saturation by secondary-ion-wave instabilities.
Abstract: We report the observation of nonlinear saturation of Langmuir waves produced by a probe laser beam interacting with a high intensity pumping laser beam. Amplification of the probe beam is observed and interpreted as scattering of pump energy by a Langmuir wave that is produced by the beating of the two beams. It is found that, as the probe beam amplitude is increased, the scattering and Langmuir wave amplitude do not increase proportionally, demonstrating that the wave is nonlinearly saturated consistent with saturation by secondary-ion-wave instabilities. {copyright} {ital 1999} {ital The American Physical Society}
25 citations
TL;DR: In this article, the Brillouin backscattered (SBS) light can be deflected in a direction opposite to transverse plasma flow by axial flow gradients.
Abstract: Three-dimensional simulations show that stimulated Brillouin backscattered (SBS) light can be deflected in a direction opposite to transverse plasma flow. When the backscatter gain occurs predominantly in the region beyond where the incident light is deflected by transverse flow, and when the backscatter gain from the deflected incident light region is detuned from the undeflected incident light region by axial flow gradients, the SBS deflection correlates well with the steering of the incident beam. The level of Brillouin backscatter gain in the presence of transverse flow is less than that in the absence of transverse flow because of convective damping, where ion acoustic waves are swept out of the high intensity regions(s) of a beam.
8 citations