A. E. Davletov

Screened pseudopotential and static structure factors of semiclassical two-component plasmas

Abstract An effective potential (pseudopotential) model of the particle interaction of semiclassical two-component plasmas, taking into account both quantum effects and collective events, is proposed. Analytical expressions for static structure factors are obtained.

Ionization equilibrium and equation of state of partially ionized hydrogen plasmas: Pseudopotential approach in chemical picture

Starting from the Bogolyubov hierarchy for the equilibrium distribution functions, a novel approach to the chemical model of partially ionized plasmas is proposed. Unlike the ordinary chemical picture it allows one to determine, in a self-consistent manner, both the ionization equilibrium and correlation functions as well. It is shown that the charged and neutral components of the plasma are closely interrelated and, as a consequence, the short-range order formation turns possible. The equation of state of partially ionized hydrogen plasmas is studied and detailed comparison with an exact quantum-mechanical expansion is made. The approach developed is quite analogous to the Debye–Huckel theory of weakly coupled fully ionized plasmas and includes it as a limiting case.

Stopping power in dense, high-temperature plasmas

Within the framework of density-response formalism and starting from the effective potential which simulates quantum effects of diffraction and symmetry, an expression for the longitudinal dielectric function of semiclassical two-component plasmas is proposed. On the basis of that dielectric function, the stopping power in dense, high-temperature plasmas is calculated. It is found that quantum effects lead to energy loss enhancement when the velocity of an injected particle is small enough. An analytical expression for the stopping power in electron plasmas is obtained in the case of large particle velocity.

Collective and static properties of model two-component plasmas.

Classical MD data on the charge-charge dynamic structure factor of two-component plasmas (TCP) modeled in Phys. Rev. A 23, 2041 (1981) are analyzed using the sum rules and other exact relations. The convergent power moments of the imaginary part of the model system dielectric function are expressed in terms of its partial static structure factors, which are computed by the method of hypernetted chains using the Deutsch effective potential. High-frequency asymptotic behavior of the dielectric function is specified to include the effects of inverse bremsstrahlung. The agreement with the MD data is improved, and important statistical characteristics of the model TCP, such as the probability to find both electron and ion at one point, are determined.

On the electrical conductivity of semiclassical two-component plasmas

Starting from a memory-function formalism coupled with the Green– Kubo formula and an approximate expression for the generalized Coulomb logarithm, the electric conductivity of a dense high-temperature hydrogen plasma is studied. A pseudopotential model, taking account of short-range quantum effects and long-range screening-field effects, is employed to include quantum mechanical and polarization effects. An analytical formula for the Coulomb logarithm is proposed when the thermal de Broglie wavelengths are rather smaller than the Debye radius. A minimum in the curve of electrical conductivity is found and some physical evidence for its appearance is produced.

Direct Determination of Dynamic Properties of Coulomb and Yukawa Classical One-Component Plasmas

Dynamic characteristics of strongly coupled classical one-component Coulomb and Yukawa plasmas are obtained within the nonperturbative model-free moment approach without any data input from simulations so that the dynamic structure factor (DSF) satisfies the first three nonvanishing sum rules automatically. The DSF, dispersion, decay, sound speed, and other characteristics of the collective modes are determined using exclusively the static structure factor calculated from various theoretical approaches including the hypernetted chain approximation. A good quantitative agreement with molecular dynamics simulation data is achieved.

Finite size effects in the static structure factor of dusty plasmas

Based on the previously developed pseudopotential model of the dust particles interaction, which takes into account both the finite size and screening effects, the equilibrium distribution functions are investigated in a broad range of plasma parameters. The treatment stems entirely from the renormalization theory of plasma particles interactions which leads to the so-called generalized Poisson-Boltzmann equation. In particular, an analytical expression for the static structure factor of the dust particles is proposed and its non-monotonic behavior in the hyper-netted chain approximation is found in a specified domain of plasma parameters to indicate the formation of short- or even long-range order in the system.

Stopping of relativistic projectiles in two-component plasmas

Relativistic and correlation contributions to the polarizational energy losses of heavy projectiles moving in dense two-component plasmas are analyzed within the method of moments that allows one to reconstruct the Lindhard loss function from its three independently known power frequency moments. The techniques employed result in a thorough separation of the relativistic and correlation corrections to the classical asymptotic form for the polarizational losses obtained by Bethe and Larkin. The above corrections are studied numerically at different values of plasma parameters to show that the relativistic contribution enhances only slightly the corresponding value of the stopping power.

Thermodynamics of partially ionized plasmas based on a pseudopotential model of particles interaction

In the framework of the BBGKY hierarchy the main features of interparticle interactions in a partially ionized hydrogen plasma are extensively studied. The theory developed is used to determine thermodynamical properties of partially ionized plasmas. Comparison is made with the quatum mechanical results available.

OML evaluation of the dust grain charge under quasineutrality conditions

Interaction potentials of electrons and ions with dust particles are developed to consistently treat plasma electrodynamics. It is assumed for the sake for simplicity that the material, the dust particles are made of, is a perfect conductor, and, then, the linear density-response formalism in the random phase approximation is used to take into account finite dimensions of grains. Additionally, the number density of protons is kept fixed such that the negative electric charge is allocated between the free electrons and the dust particles to assure the whole quasineutrality of the system. On the ground of the developed interaction potentials the electric charge of the dust particles is then calculated within the orbital motion limited (OML) approximation, which stems from the ballistic trajectories of the plasma particles at the charging process. It is rather clear that to advocate such a technique the mean free paths of the plasma particles must be much greater than the dimension of the dust grain. It is well known that under OML assumptions the conservation laws of energy and angular momentum are sufficient to determine the absorption cross sections of electrons and ions by the dust particle. The resultant absorption cross sections are then integrated over the velocity distribution distribution function to evaluate the fluxes of plasma particles on the grain surface, and the electric charge of the dust particle is stabilized when those fluxes are finally equalized.