Levan N. Tsintsadze

Overdense propagation of a relativistically intense laser light

One-dimensional (1D) propagation of a relativistically intense circularly polarized electromagnetic (EM) wave in an over-critical density plasma is investigated. Cases of fast group velocity to which ions cannot follow the motion and of slow propagation in which ion dynamics plays an important role are discussed. However, electrons can be treated as in static force balance keeping local charge neutrality. It is shown that plane waves are always unstable in the overdense plasma. In particular, two types of modulational instability are found in the case of slow propagation and their growth rates are obtained. It is also shown that an envelope solitary wave solution can be obtained in an overdense region. Density limit for the solitary wave propagation is obtained as a function of its amplitude. The solitary wave is a rarefaction wave for the case of fast propagation, while it becomes of compressional character propagating with supersonic speed for the case of slow propagation. A general expression for the propagation speed as a function of the plasma density and the solitary wave amplitude is obtained for the compressional solitary wave, and the upper and lower limits of the density (or the amplitude) for given amplitude (or density) are obtained. A three-dimensional (3D) effect is briefly discussed and a boundary value problem is formulated for the case in which the plasma fills a half space with the other half space being in vacuum. For the case of an EM wave with ultrarelativistic intensity the transmission coefficient into an over-critical density plasma is found to be a universal function of the ratio of the incident wave amplitude to the plasma density.

Kinetic formulation of neutrino–plasma interactions

A kinetic equation is derived for a neutrino gas interacting with a background plasma via the weak force. It is shown how the neutrino fluid equations can be derived from the kinetic equation. The plasma electrons are also linked with the neutrino population by a ponderomotive force term, and the neutrino–plasma interaction problem can be described as the coupling of two fluids: the electron and the neutrino fluids (the plasma ions being assumed at rest).

Corrugation instability of radiative shock waves in a relativistically hot plasma

The corrugation instability of magnetic shock waves in a relativistically hot plasma with photon gas has been investigated. Conditions under which spontaneous amplification of surface corrugations on the discontinuity occurs are obtained. The corrugation instability may cause the condensation of the plasma number density, as well as the magnetic field behind the shock wave.

Thermodynamics of a neutrino gas in a dense plasma

The thermodynamic properties of a neutrino gas in a background plasma are described, including the contribution of the weak interaction between the neutrinos and the background plasma. The free energy of the neutrino gas is calculated explicitly, thus allowing the derivation of all the relevant thermodynamic quantities. The equation of state of the neutrino gas in the plasma is also derived for different astrophysical conditions.

Stability of a charged plane surface of an electron–positron–ion plasma

A general description is presented for the stability problem of a charged surface of a plasma in the presence of a negative pressure. Conditions under which the charged surface becomes unstable are obtained. The relevance of this investigation to astrophysical and laboratory plasmas is pointed out.

Collective modes in quantum Fermi liquid

Landau’s theory of Fermi liquids is generalized by incorporating the de Broglie waves diffraction. A newly derived kinetic equation of the Fermi particles is used to derive a general dispersion relation and the excitation of zero sound is studied. A new mode is found due to the quantum correction. It is shown that the zero sound can exist even in an ideal Fermi gas. We also disclose a new branch of frequency spectrum due to the weak interaction.

Effects of High Temperature Radiation on Electrostatic Plasma Waves

The effects of black-body radiation emitted from a high temperature radiation source on electrostatic plasma wave characteristics in a relatively cold tenuous plasma are theoretically investigated. The ponderomotive force of the photons perturbed by the electron density fluctuation is taken into account. It is shown that the effect is in general very small, but has a logarithmic singularity which corresponds to a radiation induced zero-sound. A significant effect can be expected in a narrow frequency range in which the zero-sound couples with the electron plasma wave.

On the dust charging equation

A general derivation of the charging equation of a dust grain is presented, and indicated where and when it can be used. The problem of linear fluctuations of charges on the surface of the dust grain is discussed.A general derivation of the charging equation of a dust grain is presented, and indicated where and when it can be used. A problem of linear fluctuations of charges on the surface of the dust grain is discussed.

Breaking of the laser excited wakefield due to electron beam

Effects of electron beam, accelerated by a superstrong short laser pulse, on the electron plasma waves are investigated. Shock formation and subsequent wave breaking are discussed and the time and the place of the shock formation are determined for two different cases, namely the first, electron beam is modulated by a wakefield and the second, electron beam is considered with Gaussian distribution.

On the theory of relativistically intense EM wave propagation in overdense plasma and the boundary-value problem

A generalized set of equations of the plasma hydrodynamics in super-strong radiation fields is presented. A dispersion relation for an arbitrary amplitude of pump field is found and new branches for the modulational instability are disclosed. The stationary solution describing a solitary wave propagation, which has the character of a compression wave, with a constant velocity is studied and the amplitude dependence of the propagation speed of the wave is found. The irradiance threshold for the transition is obtained as a function of plasma density. The plasma compression effects are also shown by the analysis of more realistic three dimensional electromagnetic (em) wave case. The boundary conditions for the fundamental equations, which define the field in a plasma are derived and the boundary-value problem is discussed.