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The instability of ion acoustic waves due to the return current driven by an electron heat flux is a source of ion acoustic turbulence (IAT), which provides electromagnetic wave conversion into Langmuir waves at a near-critical density in inertial confinement fusion plasmas. The Langmuir waves triggered by IAT produce hot electrons. We formulate a theoretical model of hot-electron generation by these Langmuir waves and analyze it qualitatively. We show that IAT-driven hot electrons are generated in the backward direction and, therefore, preheat the target core because of the electron refluxing in the coronal plasma back toward the solid target. [ABSTRACT FROM AUTHOR]

A rigorous procedure is proposed for finding a solution to kinetic equations with the Landau electron-electron, electron-ion, ion-electron, and ion-ion collision integrals in fully ionized plasma. The linear plasma response to the perturbation in the electrostatic field is described in terms of plasma dielectric permittivity. Solutions of the dispersion relation for electron plasma waves, ion-acoustic waves, and entropy modes are found in the entire range of frequencies, wave vectors, and particle collisionality. Several fits are obtained to enable practical applications of these results. [ABSTRACT FROM AUTHOR]

The collisionless adiabatic expansion into vacuum of spherical plasma targets (clusters) composed of cold single- or multispecies ions and hot electrons is studied kinetically by numerical solving of the nonrelativistic equations of motion of plasma particles in the self-consistent electrostatic field. The expansion dynamics for the whole range of electron temperatures from much less than to much higher than the cluster Coulomb energy is described for various initial plasma density profiles and cluster structures. The explosion of two ion species heterogeneous (layered) and homogeneously mixed targets is studied in detail for the wide range of light ion concentration and kinematic parameter. [ABSTRACT FROM AUTHOR]

Axial magnetic field generation by intense circularly polarized laser beams in underdense plasmas has been studied with three-dimensional particle-in-cell simulations and by means of theoretical analysis. Comparisons between analytical models and simulation results have identified an inverse Faraday effect as the main mechanism of the magnetic field generation in inhomogeneous plasmas. The source of azimuthal nonlinear currents and of the axial magnetic field depends on the transverse inhomogeneities of the electron density and laser intensity. The fields reach a maximum strength of several tens of megagauss for laser pulses undergoing relativistic self-focusing and channeling in moderately relativistic regime. Ultrarelativistic laser conditions inhibit magnetic field generation by directly reducing a source term and by generating fully evacuated plasma channels. [ABSTRACT FROM AUTHOR]

The full set of linearized Fokker–Planck kinetic equations with Landau collision terms have been solved as an initial-value problem for equilibrium electron-ion plasmas. This work is a generalization of the nonlocal transport theory by Bychenkov et al. [Phys. Rev. Lett. 75, 4405 (1995)] to both electron and ion components with frequency-dependent responses. Transport closure relations have been obtained for the complete set of electron and ion fluid equations which are valid over the full range of particle collisionality and for an arbitrary ionic charge. The well-known limits of collisionless and strongly collisional plasma transport theory have been recovered. Practical fits based on the numerical calculations have been introduced for nonlocal and frequency-dependent ion transport coefficients. [ABSTRACT FROM AUTHOR]

The electron injection, for the laser wake field accelerator, controlled through the plasma density inhomogeneity is studied on a basis of analytical estimates and two- and three-dimensional particle-in-cell simulations. The injection scheme requires a concordance of the density scale length and laser intensity. It is shown that at a sloping inhomogeneity of plasma the wave breaking produces stronger singularity of the electron density than at a density discontinuity, but develops slower. With the help of simulations for a moderate laser intensity, we demonstrate the optimal plasma density gradient, where the electron injection into the wake wave forms the electron beam with low divergence, small energy spread and high energy. [ABSTRACT FROM AUTHOR]

Based on the solution of a linearized kinetic equation for electrons with a Landau collision integral, we develop a theory of electron transport for small perturbations in a completely ionized plasma with an arbitrary ionic charge that is free from any constraints on the characteristic perturbation time and length scales. We calculate the potential and vortex electron fluxes for an arbitrary electron collision frequency that allow the spatial and temporal nonlocal transport to be described. We also derive expressions for the longitudinal and transverse electron permittivities of a collisional plasma with an arbitrary ionic charge that are suitable for describing the plasma response to small perturbations with an arbitrary frequency and wave vector. Using the transverse permittivity, which allows the absorption of an electromagnetic wave to be described in the entire range of plasma parameters (from the strongly collisional to the collisionless one), as an example, we provide a detailed comparison with previously known models. [ABSTRACT FROM AUTHOR]

An analysis is made of how electron collisions influence the development of photoionization two-stream instability of a plasma produced in the irradiation of matter by a short X-ray pulse from a free-electron laser. The cases of a weakly ionized and a completely ionized plasma are discussed. [ABSTRACT FROM AUTHOR]

A procedure is proposed for finding a solution to the linearized kinetic equation with the Landau collision integral included for charged particles in a plasma with a high degree of ionization. This procedure is used to obtain an expression for dielectric permittivity tensor for a collisional plasma over the entire range of frequencies and wave numbers as well as the collisionality parameter. This is transformed to the known expressions in the corresponding asymptotic strongly collisional and collisionless limits. Nonlocal linear transport equations for small perturbations are also formulated for arbitrary relations between the characteristic space, time and collision scales of the plasma. [ABSTRACT FROM AUTHOR]

A regular procedure is proposed for finding the solution to a linearized kinetic equation for charged particles with the Landau collision integral in a plasma with large Z. The expression for longitudinal permittivity of a collisional plasma, which is obtained using this procedure for the entire range of frequencies and wavenumbers, as well as the collision parameter, is transformed to the known expressions in the corresponding asymptotic limits. The nonlocal transport equations for small perturbations are also formulated for arbitrary relations between the characteristic space and time scales of the plasma; these relations considerably extend the limits of applicability for previously developed theories. © 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

Quasi-self-similar solutions to the stationary electron kinetic equation in diffusive approximation have been found in an inhomogeneous plasma. Electron density and temperature corresponding to these solutions satisfy a steady state plasma profile that is defined by nTa=const (a>1). The derived electron distribution functions describe particle transport, in particular thermal conduction and ambiporal electric field for the arbitrary amplitude of temperature perturbation in the wide range of particle collisionality. The quasi-self-similar solutions display enhanced algebraic tails in the isotropic part and the reduced number of energetic electrons in the anisotropic part of electron distribution functions. The quasi-self-similar theory of electron kinetics is applied to laser plasma heating and heat transport into the overdense region. Calculations of the linear Landau damping rate, growth rate of the return current instability, and dynamical form factor are presented. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A system of nonlocal electron-transport equations for small perturbations in a magnetized plasma is derived using the systematic closure procedure of Bychenkov et al. [Phys. Rev. Lett. 75, 4405 (1995)]. Solution to the linearized kinetic equation with a Landau collision operator is obtained in the diffusive approximation. The Fourier components of the longitudinal, oblique, and transversal electron fluxes are found in an explicit form for quasistatic conditions in terms of the generalized forces: the gradients of density and temperature, and the electric field. The full set of nonlocal transport coefficients is given and discussed. Nonlocality of transport enhances electron fluxes across magnetic field above the values given by strongly collisional local theory. Dispersion and damping of magnetohydrodynamic waves in weakly collisional plasmas is discussed. Nonlocal transport theory is applied to the problem of temperature relaxation across the magnetic field in a laser hot spot. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The renormalization-group approach is used to obtain an exact solution to the self-consistent Vlasov kinetic equations for plasma particles in the quasi-neutral approximation. This solution describes the one-dimensional adiabatic expansion of a plasma bunch into a vacuum for arbitrary initial particle velocity distributions. Ion acceleration is studied for two-temperature Maxwellian and super-Gaussian initial electron distributions, which predetermine distinctly different ion spectra. The solution found is used to describe the acceleration of ions of two types. The relative acceleration efficiency of light and heavy ions as a function of atomic weights and number densities is analyzed. The solutions obtained are of practical importance in describing ion acceleration during the interaction of an ultrashort laser pulse with nanoplasma, for example, cluster plasma or plasma produced when thin foils are irradiated by a laser. [ABSTRACT FROM AUTHOR]

A self-similar solution to the stationary electron Fokker-Planck equation has been found in an inhomogeneous plasma with a given input of energy flux. This solution describes a reduction in the number of bulk electrons and the formation of a superthermal tail with a power law dependence on velocity. Significant modifications in the electron plasma wave Landau damping and return current instability growth rate have been discussed. [ABSTRACT FROM AUTHOR]

A new electron distribution function has been found in laser heated homogeneous plasmas by an analytical solution to the kinetic equation and by particle simulations. The basic kinetic model describes inverse bremsstrahlung absorption and electron-electron collisions. The non-Maxwellian distribution function is comprised of a super-Gaussian bulk of slow electrons and a Maxwellian tail of energetic particles. The tails are heated due to electron-electron collisions and energy redistribution between superthermal particles and light absorbing slow electrons from the bulk of the distribution function. A practical fit is proposed to the new electron distribution function. Changes to the linear Landau damping of electron plasma waves are discussed. The first evidence for the existence of non-Maxwellian distribution functions has been found in the interpretation, which includes the new distribution function, of the Thomson scattering spectra in gold plasmas [Glenzer et al., Phys. Rev. Lett. 82, 97 (1999)]. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The equations of vortex electron anisotropic hydrodynamics are used to show that, in a plasma with anisotropic pressure, the Weibel instability of short-wavelength perturbations gives rise to a large-amplitude quasi-harmonic magnetic field varying periodically as a function of time. The computed field parameters agree well with the proposed analytic estimates. © 2000 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Reports on the development of a theory of plasma response to electromagnetic perturbations based on full solution to the Fokker-Planck equation in high Z plasmas without electron-electron collisions. Transverse electron susceptibility for the entire range of frequencies; Application to the calculation of laser light absorption in solid density plasmas.

Discusses a theory of stimulated Raman scattering (SRS) in plasmas with an electron distribution function altered from the Maxwellian form by inverse bremsstrahlung heating. Modification of Langmuir wave collisional and Landau damping coefficients; Changes in the SRS threshold and scattered light frequency spectra.