Coulomb broadening of nonlinear resonances in a field of intense standing wave

The problem of probe-field spectrum is considered for a three-level ion placed in a field of an intense standing light wave. The ion interaction with plasma and the velocity-changing Coulomb scattering are taken into account within the weak-collision model. The system of kinetic equations for the density matrix is solved by the expansion in spatial harmonics and eigenfunctions of the collision operator. The profile of nonlinear addition to the probe-wave absorption is determined for various values of the effective ion-ion collision frequencies and various amplitudes and frequencies of standing wave. It is shown that the broadening of the central nonlinear structure in the spectrum is caused by the Coulomb dephasing effect. The computational results are in qualitative agreement with the available experimental data.     

Description of single-electron capture by fast multielectron ions

An analytical approximation of wave functions has been derived for the excited states of atoms and ions. The nuclear charge and the number of electrons are Z ≤ 10 and N _e ≤ 10, respectively. It is shown that the cross section of electron capture by fast ions must be estimated with allowance for their Coulomb interactions. The theoretical dependence between the single-electron capture cross section and the collision energy is close to the experimental, when ion interactions in the final state are taken into account. This proximity enables us to analyze the correlation between theoretical and experimental results.     

Influence of the Coulomb interaction in the final state on the cross section of single-electron capture by fast ions

It is shown that the Coulomb interaction of ions in the final state must be taken into account in the estimation of the cross section of electron capture by fast ions. The cross section of electron capture decreases considerably, and the dependence of the cross section on the collision energy becomes close to the experimental one if the interaction of charged particles after collision is taken into account.     

高能带电粒子库仑对数量子力学效应研究

 先进燃料D-3He聚变产生的高能带电粒子在本底等离子体中慢化时间的准确性直接影响到能量平衡和高能离子压强的计算结果。结果表明：高能带电粒子与本底等离子体的离子相互作用的库仑对数量子力学效应明显。应使用高能带电粒子库仑对数力学效应来研究聚变产生的高能端部粒子慢化过程;能量大于等于25Z²_iZ²_iA_i keV的高能粒子与本底等离子体中离子的相互作用库仑对数最好也使用量子截断。     

高能带电粒子库仑对数量子力学效应研究

先进燃料D-3He聚变产生的高能带电粒子在本底等离子体中慢化时间的准确性直接影响到能量平衡和高能离子压强的计算结果。结果表明：高能带电粒子与本底等离子体的离子相互作用的库仑对数量子力学效应明显。应使用高能带电粒子库仑对数力学效应来研究聚变产生的高能端部粒子慢化过程;能量大于等于25Z2iZ2iAi keV的高能粒子与本底等离子体中离子的相互作用库仑对数最好也使用量子截断。     

Effective statistical weights of bound states in plasmas

Based on recent advances in the study of the statistics of interparticle distances and angles in plasmas, we develop an approach for the determination of the effective statistical weights of atomic (ionic) quantum states in ideal and nonideal plasmas. This approach allows one to account naturally for the effects of both the perturbation of the bound states by the neighboring ions and for the binding energy reduction due to the screening of the Coulomb interaction. We analyze the roles of tunneling and overbarrier escape of the optical electron from the parent ion potential well. The effects of neighbor ions and free electrons on these processes, and the simultaneous presence of several perturber ion species in the plasma are treated. We show that the present approach offers significantly more accurate effective-statistical-weight values in comparison to the existing theoretical treatments, and yields physical expressions for the empirical factors of the existing theories. Examples of calculations of effective statistical weights are given. The effects of the atomic (ionic) states collectivization on the collisional-radiative kinetics of dense plasmas are discussed. Received 10 August 2001     

Electron capture processes in strongly coupled semiclassical plasmas

The electron captures by projectile ions from hydrogenic ions are investigated in strongly coupled semiclassical plasmas. The electron capture radius by the projectile ion is obtained by the effective screened pseudopotential model taking into account both the plasma screening and quantum effects. The semiclassical version of the Bohr-Lindhard method is applied to obtain the electron capture probability. The impact-parameter trajectory analysis is applied to the motion of the projectile ion in order to visualize the electron capture radius and capture probability as functions of the impact parameter, thermal de Broglie wavelength and Debye length. The results show that the quantum and plasma screening effects significantly reduce the electron capture probability and the capture radius. It is found that the electron capture position is shifted to the core of the projectile ion with increasing the thermal de Broglie wavelength. It is also found that the quantum effects on the electron capture probability are more significant than the collective screening effects on the electron capture probability. The electron capture probability is found to be significantly increased with an increase of the charge.Received: 27 June 2003PACS: 52.20.-j Elementary processes in plasmasYoung-Dae Jung: Permanent address: Department of Physics, Hanyang University, Ansan, Kyunggi-Do 425-791, South Korea, yjung@bohr.hanyang.ac.kr     

THEORY OF RAMAN SCATTERING FROM CHARGE DENSITY-WAVE SUPERCONDUCTORS

A theory is developed for the Raman scattering of light from a charge-density-wave (CDW) superconductor on the basis of a modified Balseiro-Falicov interactibn pro.posed by the authors and including renormalization of both the Coulomb interaction at the small q limit, and the residual coupling between electrons. Both the electron-photon and electron-phonon vertices are taken into account. It is shown that there always exist poles at frequency ω=2Δ (Δ is superconducting gap) in the effective electron polarization and in the phonon self-energy, and these poles survive the Coulomb screening and the renormalization of the residual electron interactions if the coupling parameter g₂(k) is anisotropic, in contrast with an isotropic electron gas. The effect of the Littlewood-Varma interaction in a coexistent CDW-siiperconductcr is also discussed.     

Sheath structure in plasma with two species of positive ions and secondary electrons

The properties of a collisionless plasma sheath are investigated by using a fluid model in which two species of positive ions and secondary electrons are taken into account. It is shown that the positive ion speeds at the sheath edge increase with secondary electron emission(SEE) coefficient, and the sheath structure is affected by the interplay between the two species of positive ions and secondary electrons. The critical SEE coefficients and the sheath widths depend strongly on the positive ion charge number, mass and concentration in the cases with and without SEE. In addition, ion kinetic energy flux to the wall and the impact of positive ion species on secondary electron density at the sheath edge are also discussed.     

Ion acoustic solitons in a relativistic warm plasma with densitygradient

Modified Korteweg-deVries equation (mK-dV), which governs the behavior of ion acoustic solitons in a relativistic warm plasma with density gradient, is derived. The electron inertia is also taken into account which is important when the streaming ions are present in the plasma. A solution of the mK-dV equation is obtained for the constant density gradient. When the ion acoustic soliton propagates into the lower plasma density region, its amplitude and energy increase, but the width decreases; the same is the case for the stronger density gradients     

Dipole polarizabilities of plasma-embedded Ps and H ions

We have investigated the effect of weakly coupled hot plasmas on the dipole polarizabilities of positronium negative ion and hydrogen negative ion. The plasma effect is taken care of by employing a screened Coulomb (Yukawa) potential of Debye type, and highly correlated exponential wave functions are used. Dipole polarizabilities for various screening parameters are reported.     

Modelling of the Positive Column in an Argon-Hexamethyl-disiloxane dc Glow Discharge

A model is presented of the positive column of a dc glow discharge in argon with small admixtures of hexamethyldisiloxane (HMDS). The axial electric field, the ion production rates for direct-, stepwise-, pair-, and Penning ionization, the densities of metastable Ar atoms and of electrons, and the wall current of HMDS ions are calculated in dependence on HMDS admixture and discharge current density. For the calculations particle balance equations were used for a diffusion determined plasma in a mixture of two gaseous components. The reaction rates for the electron collision processes were determined applying the electron distribution function calculated for pure argon. Taking into account PENNING ionization of HMDS molecules by metastable argon atoms the decrease of electric field for increasing HMDS admixtures is according to the experimen-tally measured values. Also ion wall currents and electron densities are compared with experimen-tal values for thin film formation rate and results of probe measurements.     

Coulomb explosion patterns of fast C60 clusters in solids

The molecular dynamics method is used to simulate Coulomb explosion of fast C60 ion clusters in an Al target, taking into account dynamical screening of interionic interactions by the electron gas of the target. It is found that the wake forces in the medium are strong enough, depending on cluster speed, to stabilize the whole cluster against Coulomb explosion, or to compress the trailing part of the cluster, for prolonged times of penetration through the target. This is encouraging news for such cluster-ion beams applications where massive energy depositions in small volumes of targets are desired.     

Ion separation due to magnetic field penetration into a multispecies plasma

The magnetic field, the electron density, and the ion velocities in a multispecies plasma conducting a high fast-rising current are determined using simultaneous spectroscopic measurements. It is found that ion separation occurs in which a light-ion plasma is pushed ahead while a heavy-ion plasma lags behind the magnetic piston. We show that most of the momentum imparted by the magnetic field pressure is taken by the reflected light ions, and most of the dissipated magnetic field energy is converted into kinetic energy of these ions, even though their mass is only a small part of the total plasma mass. Such species separation with implications to the momenta and energy partitioning is shown to be of a general nature.     

Plasmons in strong superconductors

We present a study of the possible plasmon excitations that can occur in systems where strong superconductivity is present. In these systems the plasmon energy is comparable to or smaller than the pairing gap. As a prototype of these systems we consider the proton component of Neutron Star matter just below the crust when electron screening is not taken into account. For the realistic case we consider in detail the different aspects of the elementary excitations when the proton, electron components are considered within the Random-Phase Approximation generalized to the superfluid case, while the influence of the neutron component is considered only at qualitative level. Electron screening plays a major role in modifying the proton spectrum and spectral function. At the same time the electron plasmon is strongly modified and damped by the indirect coupling with the superfluid proton component, even at moderately low values of the gap. The excitation spectrum shows the interplay of the different components and their relevance for each excitation modes. The results are relevant for neutrino physics and thermodynamical processes in neutron stars. If electron screening is neglected, the spectral properties of the proton component show some resemblance with the physical situation in high-T _c superconductors, and we briefly discuss similarities and differences in this connection. In a general prospect, the results of the study emphasize the role of Coulomb interaction in strong superconductors.     

Statistical theory of a solvated electron in an electrolyte

The behavior of a solvated electron in an electrolyte is investigated. The formalism of the theory is based on variational estimation of path integrals. It reduces the problem to the investigation of the self-consistent mean field produced by the ions and the electron. Mayer cluster expansions make it possible to take account of the short-range interactions and to find expressions for the effective potential of the electron and the electron-ion and electron-neutral atom correlation functions as a function of the macro-and microscopic parameters of electrolytes. In the limit of high ion densities the behavior of the electron is determined solely by the Coulomb interaction, which results in the formation of a polaron state. This state of the electron is virtually independent of the thermodynamic parameters of the electrolyte. In the opposite limit of low ion densities the electron forms a cavity state. The presence of ions results in additional localization of the electron and is manifested experimentally as a shift of the absorption band in the direction of high energies. The estimated shift for a hydrated electron agrees with the experimental data. Zh. éksp. Teor. Fiz. 115, 1463–1477 (April 1999)     

低能电子碰撞He+(e,2e)反应绝对三重微分截面的理论研究

利用Berakdar和Briggs对BBK波函数Sommerfeld参数的修正结果，即考虑第三个粒子存在对两个粒子间相互作用的影响，考虑了入射道的库仑相互作用及出射粒子的交换对称性，计算了在共面等能分配几何情况下低能电子碰撞He⁺(e,2e)反应绝对三重微分截面.结果表明，入射道库仑场对较低的入射能量及小的碰撞参数的三重微分截面影响较大. 关键词：     

Collective braking mechanism in plasma and the momentum-transfer distribution function

It is shown that the lower limit in the Coulomb logarithm is determined by the collective behavior of the plasma and not binary collisions with small impact parameters. For this reason, the assumption that the “largest” momentum transfer is determined by binary collisions results in a factor of two overestimation of the numerical coefficient in the second moment of the momentum transfer, i.e., the multiparticle nature of the lower limit in the Coulomb logarithm affects not only the logarithm itself but also the numerical coefficient multiplying it. Correctly taking into account fluctuational electric fields with scales less than or of the order of the Debye radius (multiple nature of collisions in plasma) substantially changes the physics of Coulomb collisions and results in the appearance of a new characteristic scale in plasma theory, (r _D rmin)^1/2, which has no analog in kinetic problems with a non-Coulomb interaction potential. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 1, 18–23 (10 July 1999)     

Certain properties of an electrically insulated Coulomb plasma. Numerical simulation of microfields and thermodynamic properties. the problem of ball lightning

Many-body dynamics is used to study the (quasi-)steady state of a classical Coulomb plasma. The shortest relaxation time in such a plasma, for both the Debye screening and the thermodynamic properties, is the electron transit time over the average distance between ions. The steady-state energy of the Coulomb interaction of the particles and the steady-state potential near a fixed charge can be described well by the Debye-Hückel theory, even if there is less than a single particle in a Debye sphere, on the average. Distributions of instantaneous values of the microfields in the plasma are derived. The results calculated for the electron turning distance are compared with the results of the quasibinary theory. An attempt is made to link the anomalously long lifetime of the plasma of ball lightning to a retardation of the recombination of a classical Coulomb plasma in the absence of a stochastic external agent.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 10–23, February, 1992.     

ELECTRON IMPACT IONIZATION OF A HYDROGENIC ION AT INTERMEDIATE AND LOW ENERGIES

１ＩＮＴＲＯＤＵＣＴＩＯＮＥｌｅｃｔｒｏｎｃｏｌｉｓｉｏｎｗｉｔｈａｔｏｍｓａｎｄｉｏｎｓｐｌａｙｓａｐｒｏｍｉｎｅｎｔｒｏｌｅｆｏｒｔｈｅｄｉａｇｎｏｓｔｉｃｏｆｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｐｌａｓｍａｏｃｕｒｉｎｇｎａｔｕｒａｌｙｉｎｓｔａｒ...