Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 11
    Electronic Resource
    Electronic Resource
    Suppression of stimulated Brillouin scattering by seeded ion wave mode coupling (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 3402-3407 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Particle simulations and the analytical solution of coupled mode equations are used to demonstrate that the mode coupling of a primary ion acoustic wave produced by stimulated Brillouin backscatter with a secondary finite-amplitude ion wave propagating at a finite relative angle can reduce the amplitude of the primary ion wave and the backscatter. The simulations and analysis give results that are in qualitative agreement with experimental observations [Baldis et al., Phys. Rev. Lett. 77, 2957 (1996)] of the partial suppression of stimulated Brillouin backscattering (SBBS) when there are simultaneous, overlapping SBBS processes at a finite relative angle, which may influence SBBS reflectivities in other current and future laser-fusion experiments with multiple overlapping beams. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.873054
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Resonant stimulated Brillouin interaction of opposed laser beams in a drifting plasma (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 3408-3415 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Particle simulations and solutions of coupled mode equations are used to analyze the energy transfer between two equal-frequency, opposed laser beams resonantly interacting with ion acoustic waves in a plasma drifting at the sound speed. The simulations and analysis illustrate the dependence of the energy transfer and the ion wave dynamics on laser intensities and detuning, and the time dependence of the phenomena. The simulation results are in qualitative agreement with experimental observations in the NOVA laser facility [E. M. Campbell et al., Rev. Sci. Instrum. 57, 2101 (1986)] at the Lawrence Livermore National Laboratory. This work is part of a continuing examination of possible resonant crossed-beam interactions in flowing plasmas and their potential effects on the fusion performance of current and future laser-fusion experiments with multiple crossing beams, e.g., proposed experiments in the National Ignition Facility [National Tech. Info. Service Document Nos. DE95017671-DE95017673 and DE95017676-DE95017700 (J. A. Paisner, E. M. Campbell, and W. J. Hogan, The Natl. Ignition Facility Project, UCRL-JC-117397 and UCRL-PROP-117093, May, 1994)]. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.873055
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Effects of laser beam smoothing on stimulated Raman scattering in exploding foil plasmas (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 1728-1736 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Time-resolved spectra of backward stimulated Raman scattering (SRS) were measured from the interaction of a 527 nm laser with a preformed plasma. The effect of laser smoothing by spectral dispersion (SSD) was studied using laser bandwidth (Δλ/λ=0.1%) and varying the laser intensity (2–20×1014 W/cm2). A broad SRS spectrum extending to short wavelengths was observed for the high-intensity, Δλ/λ=0 case. Narrow spectra corresponding to the peak plasma density were observed for cases with either high intensity and Δλ/λ∼0.1%, or with low intensity and Δλ/λ=0. Simulations of the filamentation process were performed for the conditions of these experiments. The simulations show that laser smoothing stabilizes filamentation for high-intensity interactions, and that filaments are stable without smoothing for low intensity. The predicted onset of filamentation without smoothing correlates with the growth of short wavelength SRS. These experimental results are presented and models are discussed that may help explain the data. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871682
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Beam smoothing effects on the stimulated Brillouin scattering (SBS) instability in Nova exploding foil plasmas (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 4285-4296 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of beam smoothing on the stimulated Brillouin and Raman backscattering instabilities (SBBS and SRBS) in a long scale length exploding foil plasma are experimentally investigated using the Nova laser. We observe strongly time-dependent and blueshifted SBS emission and broadband SRS emission in time-resolved spectral measurements of the backscattered light. The results of this paper focus on the SBS scattering, where we find that random phase plate spatial beam smoothing leads to a decrease in the total SBS reflectivity. Adding temporal smoothing to this spatial smoothing leads to an even greater decrease in the total reflectivity, as well as changes in the spectral nature of the backscattered light. Beam smoothing induced changes to the instabilities are limited to plasmas with a peak density below about 0.2ncr; beam smoothing causes little change in the backscattered emission for higher densities. We describe the measurements and discuss models that may explain certain aspects of the results. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871053
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Drive characterization of indirect drive targets on the Nova laser (invited) : Proceedings of the tenth topical conference on high temperature plasma diagnostics (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 678-682 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The indirect drive method of inertial confinement fusion uses a high-Z radiation case to convert energy from high-powered laser beams to x rays which implode fusion capsules. Experiments have been performed on the Nova laser to characterize the x-ray production in high-Z cavities for studying the efficiency for x-ray production using two methods for characterization. One method measures the shock velocity produced in low-Z materials by the radiation. The shock velocity is measured by observing the optical signal from the rear of a stepped or continuously varying thickness of Al placed over a hole in the cavity wall. The other method measures the reradiated x-ray flux from the cavity wall viewing through a hole in the cavity. Both methods have been shown to provide a consistent characterization of the x-ray drive in the cavity target. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146258
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Te measurements in open- and closed-geometry long-scale-length laser plasmas via isoelectronic x-ray spectral line ratios : Proceedings of the tenth topical conference on high temperature plasma diagnostics (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 749-751 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have successfully employed isoelectronic line ratios to measure the electron temperature in gas-filled hohlraums and "gas bags'' shot with the Nova laser. Isoelectronic line ratios are well suited to this measurement because they are relatively insensitive to radiation field effects (in hohlraums), opacity, transients, and variations in electron density compared to conventional line ratios. Targets were designed to produce plasma parameters Te∼3 keV and Ne∼1021 cm−3 over a scale length of ∼2 mm. Collisional-radiative, transient K-shell atomic kinetics calculations including line transfer were performed by post-processing the Lasnex results. By comparing these calculations with experimental data, we infer electron temperatures of at least 3 keV for both types of targets. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146278
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Measurements of absorption and Brillouin sidescattering from planar plasmas produced by 0.53 μm laser light (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 1295-1300 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A study of the absorption and scattering of laser light by planar, laser-produced plasmas is reported. Up to 4 kJ of 0.53 μm laser light irradiated thick, gold targets in 1 nsec pulses at intensities up to 4×1015 W/cm2. The absorption was determined from measurements of the scattered light by an array of about 100 detectors. Stimulated Brillouin sidescattering, identified by the angular distribution and spectrum of the scattered light, exceeded 10% of the laser energy for intensities above 1015 W/cm2. The observations are compared to those of previously reported experiments. It is suggested that a combination of collisional absorption, enhanced backscattering, and convective sidescattering produces the observed dependence on laser intensity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.858953
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    The angular dependence of the absorption of 0.35 μm laser light by high-Z, laser-produced plasmas (1991)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 3477-3484 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experiments to study the angular dependence of laser-light absorption in long-scale-length, planar plasmas are reported. Flat-topped, 1 nsec pulses of 0.35 μm laser light, with up to 2.5 kJ at average laser intensities of 3×1013 to 6×1015 W/cm2, were used to irradiate thick, gold targets at angles of incidence of 0° to 〉50°. The scattered light was measured using a number of diagnostics, and the absorption was inferred from these measurements. The absorption decreased somewhat with increasing laser intensity, typically remaining above 90% for laser intensities below 1015 W/cm2, and was very weakly dependent upon the angle of incidence. Modeling of the reflected light was used to constrain the properties of the plasma and of the reflecting mechanism. No simple model of a single mechanism is consistent with all aspects of the data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859776
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Laser-intensity scaling experiments in long-scalelength, laser-produced plasmas (1988)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 31 (1988), S. 1795-1802 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An experimental technique is demonstrated that allows variation of the average laser intensity by more than two orders of magnitude while producing much smaller changes in the other parameters that determine the laser–plasma interactions. By irradiating exploding-foil targets with 0.35 μm laser light in flat-topped pulses of variable duration, the high-power Nova laser [Rev. Sci. Instrum. 57, 2101 (1986)] produced plasmas with electron temperatures of order 1 keV and with scale lengths of the (radial and axial) electron-density gradients of order 1000 laser wavelengths. By using a constant target thickness and systematically decreasing the pulse length and spot size as laser intensity increased, the changes in the temperature and in the scale lengths were minimized. The time-resolved spectrum of the Raman-scattered light was used to measure both the electron temperature and the maximum density of the expanding plasmas. In this paper, these measurements are compared to both 1-D models and 2-D simulations. The expected trends of slower burnthrough and lower temperature with lower laser intensity were observed. However, the inferred temperatures are lower and the burnthrough of the target (at high laser intensities) is slower than the modeling predicts. Possible sources of these discrepancies are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866669
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Theory and three-dimensional simulation of light filamentation in laser-produced plasma (1993)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 2243-2258 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A desire to interpret recent experiments on filamentation with and without beam-smoothing techniques led to the development of a three-dimensional fluid model that includes the effects of nonlocal electron transport and kinetic ion damping of the acoustic waves. The damping of the electron-temperature perturbations that drive thermal filamentation by nonlocal electron conduction, valid in the diffusive limit, is supplemented in the present model by electron Landau damping in the collisionless limit when the wavelength of the perturbation is much less than the electron–ion scattering mean-free path. In this collisionless limit, Landau damping of the "temperature'' fluctuations makes ponderomotive forces universally more important than thermal forces. Simulations in plasmas of current interest illustrate the relative importance of thermal and ponderomotive forces for strongly modulated laser beams. Although thermal forces may initiate filamentation, the most intense filaments are associated with ponderomotive forces. The present simulations of filamentation model well the density perturbations observed in experiments [Young et al., Phys. Rev. Lett. 61, 2336 (1988)]. In addition, a simple criterion is obtained analytically and supported by simulations for stabilization of filamentation by laser beam-smoothing techniques such as induced spatial incoherence and random phase plates [Eq. (1)].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860758
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...