Landau-fluid simulation of laser filamentation

Journal Article · Sun May 01 04:00:00 EDT 1994 · Physics of Plasmas; (United States)

DOI:https://doi.org/10.1063/1.870727· OSTI ID:5007225

Kaiser, T B; Cohen, B I; Berger, R L; Lasinski, B F; Langdon, A B; Williams, E A ^[1]

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1. University of California, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

The Landau-fluid model is a recently introduced fluid-moment closure scheme [G. W. Hammett and F. W. Perkins, Phys. Rev. Lett. [bold 64], 3019 (1990)] that was designed to include kinetic dissipative effects like Landau damping in fluid calculations. The fluid-moment hierarchy is terminated by assuming linear relationships among the retained moments in Fourier-transform space, with coefficients determined by matching the plasma response to that obtained from a kinetic analysis. This paper generalizes the technique to the full range of ion and electron collisionality and applies it to a new fluid simulation code constructed to study laser filamentation in underdense plasmas [Berger [ital et] [ital al]., Phys. Fluids B [bold 5], 2243 (1993)]. By matching the ion-acoustic complex frequency derived from the fluid model with that predicted by collisional, Fokker--Planck, and kinetic analyses, the specific heat ratio, thermal conductivity coefficient, and viscosity coefficient for ions and the thermal conductivity coefficient for electrons are determined as functions of the wave number [ital k]. For frequencies much less than the pump frequency this leads to a fourth-order polynomial dispersion relation whose spectrum includes damped ion-acoustic waves as well as filamentation modes whose stability depends on the pump strength. An analytic instability threshold condition on the laser intensity is derived from which the relative importance of ponderomotive and thermal drives can be assessed. Expressions for the linear susceptibilities in the presence of a finite-amplitude pump are also given, which might prove useful for understanding spectral linewidths for Thomson scattering.

• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5007225
• Journal Information: Physics of Plasmas; (United States), Journal Name: Physics of Plasmas; (United States) Vol. 1:5; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700330* -- Plasma Kinetics
Transport
& Impurities-- (1992-)
700340 -- Plasma Waves
Oscillations
& Instabilities-- (1992-)
BEAM-PLASMA SYSTEMS
COLLISIONAL PLASMA
CONFINEMENT
ELECTROMAGNETIC RADIATION
EQUATIONS
INERTIAL CONFINEMENT
ION ACOUSTIC WAVES
ION WAVES
KINETIC EQUATIONS
LASER RADIATION
LASER-PRODUCED PLASMA
PHYSICAL PROPERTIES
PLASMA
PLASMA CONFINEMENT
PLASMA SIMULATION
PLASMA WAVES
PONDEROMOTIVE FORCE
RADIATIONS
SIMULATION
SPECIFIC HEAT
THERMAL CONDUCTIVITY
THERMODYNAMIC PROPERTIES
VISCOSITY