Observed insensitivity of stimulated Raman scattering on electron density

The results from experiments in quasihomogeneous plasmas to evaluate the potential threat of high laser reflectivity from stimulated Raman scattering (SRS) to inertial-confinement fusion (ICF) are presented. The SRS laser reflectivity is observed to be sizable (up to 50%) and very weakly dependent on electron density (and kλD), over a large range of density that corresponds to a large variation in Landau damping of plasma waves. In contrast, the reflectivity increases monotonically over time, along with ion temperature, until gross hydrodynamic activity interferes with SRS. This is consistent with previous observations of SRS reflectivity scaling with the damping rate of ion acoustic waves [Fernandez et al., Phys. Rev. Lett. 77, 2702 (1996); Kirkwood et al., ibid. 77, 2706 (1996)]. The data from plasmas with the highest kλD values indicate anomalously low damping rates for the SRS plasma wave.

[1]  Kunioki Mima,et al.  Random Phasing of High-Power Lasers for Uniform Target Acceleration and Plasma-Instability Suppression , 1984 .

[2]  Erlan S. Bliss,et al.  Nova experimental facility (invited) , 1986 .

[3]  R. Kirkwood,et al.  Measurements of laser-plasma instability relevant to ignition hohlraums , 1996 .

[4]  J. Moody,et al.  Imaging backscattered and near to backscattered light in ignition scale plasmas (invited) , 1997 .

[5]  A. Bruce Langdon,et al.  Nonlinear Inverse Bremsstrahlung and Heated-Electron Distributions , 1980 .

[6]  R. Berger,et al.  Effect of plasma noise spectrum on stimulated scattering in inhomogeneous plasma , 1989 .

[7]  Williams,et al.  Effect of Ion-Wave Damping on Stimulated Raman Scattering in High-Z Laser-Produced Plasmas. , 1996, Physical review letters.

[8]  J. Lindl.  Development of the indirect‐drive approach to inertial confinement fusion and the target physics basis for ignition and gain , 1995 .

[9]  R. P. Drake,et al.  The influence of subsidiary Langmuir decay on the spectrum of stimulated Raman scattering , 1991 .

[10]  D. F. DuBois,et al.  The effect of kinetic processes on Langmuir turbulence , 2000 .

[11]  A. J. Morgan,et al.  Random phase plates for beam smoothing on the Nova laser. , 1993, Applied optics.

[12]  C. T. Dum.  Anomalous heating by ion sound turbulence , 1978 .

[13]  H. Rose.  Saturation of Stimulated Brillouin Scatter by Self Consistent Flow Profile Modification , 1997 .

[14]  D. Harris,et al.  Ignition target design and robustness studies for the National Ignition Facility , 1996 .

[15]  C. Moller,et al.  Non-Maxwellian electron distributions and continuum X-ray emission in inverse Bremsstrahlung heated plasmas , 1988 .

[16]  Rose,et al.  Observed Dependence of Stimulated Raman Scattering on Ion-Acoustic Damping in Hohlraum Plasmas. , 1996, Physical review letters.

[17]  Wolf D. Seka,et al.  OPTICAL MIXING CONTROLLED STIMULATED SCATTERING INSTABILITIES , 2001 .

[18]  H. Rose,et al.  Characterization of plasma and laser conditions for single hot spot experiments , 1999 .

[19]  D. Dubois,et al.  Transient enhancement and detuning of laser-driven parametric instabilities by particle trapping. , 2001, Physical review letters.

[20]  Rose,et al.  Laser hot spots and the breakdown of linear instability theory with application to stimulated Brillouin scattering. , 1994, Physical review letters.

[21]  V. Tsytovich.  Nonlinear effects in plasmas , 1990 .

[22]  Peter A. Amendt,et al.  Design and modeling of ignition targets for the National Ignition Facility , 1995 .

[23]  J. Nuckolls,et al.  Laser Compression of Matter to Super-High Densities: Thermonuclear (CTR) Applications , 1972, Nature.

[24]  J. Moody,et al.  Evidence of plasma fluctuations and their effect on the growth of stimulated Brillouin and stimulated Raman scattering in laser plasmas , 1998 .

[25]  M. Rosenbluth.  Parametric Instabilities in Inhomogeneous Media , 1972 .

[26]  M. Goldman,et al.  Parametrically Excited Plasma Fluctuations , 1967 .

[27]  Bradley,et al.  Dependence of stimulated Brillouin scattering on laser intensity, laser f number, and ion species in hohlraum plasmas. , 1996, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[28]  A. Schmitt,et al.  Time-dependent filamentation and stimulated Brillouin forward scattering in inertial confinement fusion plasmas , 1998 .

[29]  K. Sanbonmatsu,et al.  New Paradigm for the Self-Consistent Modeling of Wave-Particle and Wave-Wave Interactions in the Saturation of Electromagnetically Driven Parametric Instabilities , 1999 .

[30]  S. Karttunen.  Ion fluctuation effects on the two-plasmon decay and stimulated Raman scattering , 1981 .

[31]  D. F. DuBois,et al.  Nonlinear saturation of stimulated Raman scattering in laser hot spots , 1999 .

[32]  K. Spatschek,et al.  Electromagnetic wave generation in a beam-plasma system , 1983 .

[33]  A. B. Langdon,et al.  On the dominant and subdominant behavior of stimulated Raman and Brillouin scattering driven by nonuniform laser beams , 1998 .

[34]  Bedros Afeyan,et al.  Kinetic Theory of Electron-Plasma and Ion-Acoustic Waves in Nonuniformly Heated Laser Plasmas , 1998 .

[35]  Baker,et al.  Thomson Scattering Measurements of the Langmuir Wave Spectra Resulting from Stimulated Raman Scattering. , 1996, Physical Review Letters.

[36]  H. Rose,et al.  Statistical properties of laser hot spots produced by a random phase plate , 1993 .

[37]  Rose,et al.  Saturation of stimulated Raman scattering by the excitation of strong Langmuir turbulence. , 1993, Physical review letters.

[38]  M. Goldman,et al.  Stimulated Incoherent Scattering of Light from Plasmas , 1965 .