Distribution of a nonstationary electron beam in a dense gas

The problem of the temporal and spatial dependences of the parameters of the action of a modulated fast-electron beam on a dense gas is posed on the basis of the transport equation. The problem is simplified by making it nondimensional and by transforming to the Fokker-Planck approximation. A Green's function formalism is developed for this problem and is used to express the solution of the general nonstationary problem in the form of a convolution of a nonstationary boundary flow with a stationary Green's function. The use of the derived equation is illustrated using as an example the solution of a problem with the simplest stationary Green's function corresponding to the straight-ahead approximation. This approximation is used to consider a general relativistic case with model scattering cross sections. The methods and results of a numerical computer solution of the nonstationary problem of electron retardation in the upper layer of the atmosphere are surveyed.Translated from Trudy Ordena Lenina Fizicheskogo Instituta im. P. N. Lebedeva AN SSSR, Vol. 145, pp. 172–188, 1984.     

Microscopic theory of some surface effects in a dense electron gas

We consider interacting electrons confined to a slab of finite thickness or a half space in the random phase approximation. The electronic charge is assumed to be neutralized by a homogeneous positive background. A linear response function is introduced from which it is possible to calculate the induced density variation of the electron gas, caused by an external field. The linear response function also determines the Helm-holtz free energy and, by a sum rule, the density of the undisturbed system. The interaction of a classical point charge with the electrons of a half-space is discussed. In addition, a formula for the surface energy is given.     

Inhomogeneous polarizable medium as a model for an electron gas in a nonconducting crystal

The response of the electron system to an external perturbation in an insulating medium is considered in the context of the electron density functional method. The energy functional minimization relies on the proper choice of the trial function considering different spatial scales of the electron polarization. An efficient scheme for the density functional parametrization is suggested. The electron response to atomic displacements and external electric fields has been calculated for a simple model of electron polarization centers embedded into the homogeneous dielectric background. Good agreement with the experiment is achieved for the phonon spectra ofSi, Ge, and α-Sn. The electron density induced in the external homogeneous electric field is in good agreement with that calculated by the well-known ab initio methods. V. D. Kuznetsov Siberian Physical-Technical Institute at Tomsk State University. Translated for Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6 pp. 30–37, June, 1999.     

Enhanced electron field emission from dense Si nano-dots prepared by laser crystallization of ultrathin amorphous Si films

Dense Si nano-dots with a surface area density of >10¹⁰ cm^?2 were fabricated by excimer laser induced crystallization of 15 nm-thick amorphous Si thin films. The enhanced electron field emission characteristics were found from laser irradiated samples. The threshold electric field is as low as 9.8V/μm and the field enhancement factor can reach as large as 719, which is compatible with the other good cold cathode materials. The improvements in field emission behavior can be associated with the change in the surface morphology after laser irradiation as well as the enhanced internal electric field due to the formation of Si nano-dots within the films.     

Classical modelization of symmetry effects in the dense high-temperature electron gas

A Kramerslike classical pseudopotential which includes Diffraction and Symmetry effects is worked out for k_BT?1 Ry.     

Short-range behavior of the pair correlation function in the dense electron gas

An effective Coulomb interaction taking into account the diffraction effects is used to sum the series of bubbles diagrams building up the short-range part of the pair correlation function.     

用于温密物质研究的强流电子束加载技术

能量20 MeV、流强2.5 kA的电子束脉冲可以在数十ns的时间内将靶材料加载至温密物质状态,进而可以开展材料状态方程、电导率以及不透明度等的实验研究工作。介绍了在神龙一号加速器上开展温密物质实验研究的束靶作用方式以及相应的测试技术。对电子束在直径0.3 mm、长1 mm的金属靶丝内的能量沉积和流体动力学响应进行了数值模拟。结果表明:靶丝的温度随着靶材料原子序数的增加而上升,而靶丝内温度分布的均匀性随着原子序数的增加而降低;在电子束加载后40 ns时刻Ta丝内的最高温度可以达到约1.6 eV。     

Kinetic theory of long time tails in velocity correlation functions in a moderately dense electron gas

The long time tails of the correlation functions that determine the self-diffusion coefficient and the kinetic parts of the shear viscosity and heat conductivity in a one-component plasma are calculated using a systematic kinetic theory. The results are in agreement with those obtained from the phenomenological mode coupling theory. The formal kinetic theory calculations of previous workers, who obtained incomplete long time tail results, are also discussed.     

On electron mobility in dense gas and liquid with high atomic polarizability

Renormalization of the scattering length considerable at high polarizability values, helps describe the mobility increase with density.     

On electron mobility in dense gas and liquid with high atomic polarizability

Renormalization of the scattering length considerable at high polarizability values, helps describe the mobility increase with density.     

A study of the propagation of a quasistationary relativistic electron beam in a dense gas. Part I. A physical model of the interaction

V. I. Lenin All-Union Institute of Electrical Engineering. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol 34, No. 1, pp. 70–76, January, 1991.     

Pion condensation in a dense neutrino gas

We argue that using an equilibrated gas of neutrinos it is possible to probe the phase diagram of QCD for finite isospin and small baryon chemical potentials. We discuss this region of the phase diagram in detail and demonstrate that for large enough neutrino densities a Bose–Einstein condensate of positively charged pions arises. Moreover, we show that for non-zero neutrino density the degeneracy in the lifetimes and masses of the charged pions is lifted.     

Kinetic equation for a dense soliton gas

We propose a general method to derive kinetic equations for dense soliton gases in physical systems described by integrable nonlinear wave equations. The kinetic equation describes evolution of the spectral distribution function of solitons due to soliton-soliton collisions. Owing to complete integrability of the soliton equations, only pairwise soliton interactions contribute to the solution, and the evolution reduces to a transport of the eigenvalues of the associated spectral problem with the corresponding soliton velocities modified by the collisions. The proposed general procedure of the derivation of the kinetic equation is illustrated by the examples of the Korteweg-de Vries and nonlinear Schr?dinger (NLS) equations. As a simple physical example, we construct an explicit solution for the case of interaction of two cold NLS soliton gases.     

A neutral gas model for electron swarms

A BGK-type Boltzmann equation for a neutral gas is considered as a model for electron swarms, because the gas and the electron Boltzmann equation have a common diffusion approximation. Both full- and half-range theory are developed using orthogonality methods of solution. Preliminary comparisons with diffusion theory are presented.     

A study of the propagation of a quasistationary relativistic electron beam in a dense gas. II. Experimental studies

Results obtained from experimental studies of the interaction between a quasistationary electron beam (300 keV, 20 A, 500 sec, 0.3 cm) and a dense gas are presented. These investigations were carried out in air at atmospheric pressure and, for the purpose of modeling the propagation of a magnetostricted REB, at reduced pressure (3–300 torr). The rarefaction dynamics of a channel heated by the beam are studied and its maximum propagation distances in a dense gas are determined. The results obtained are compared with the theoretical model examined earlier.V. I. Lenin All-Union Institute of Electrical Engineering. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 2, pp. 190–197, February, 1991.     

Some methods of electron-beam entry into a dense gas

A system is considered of pumping a laser with an electron beam that moves relative to the active medium. The problem of planar two-dimensional gas flow through a bounded heat-releasing medium, a problem analogous to that of rectilinear motion of a beam with constant velocity, is solved analytically. It is proposed to admit an electron beam into a dense gas through aerodynamic ports. The effect of perturbations induced by the beam passage on the flow of gas in an aerodynamic port with a rarefaction wave is analyzed.Translated from Trudy Ordena Lenina Fizicheskogo Institute im. P. N. Lebedeva AN SSSR, Vol. 145, pp. 160–171, 1984.     

Calculation of transport coefficients for a moderately dense gas

Russian Physics Journal -