共查询到20条相似文献,搜索用时 15 毫秒
1.
Young-Dae Jung 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(2):351-354
In nonideal classical plasmas, the electron captures by positrons from hydrogenic ions are investigated. An effective pseudopotential
model taking into account the plasma screening effects and collective effects is applied to describe the interaction potential
in nonideal plasmas. The classical Bohr-Lindhard model has been applied to obtain the electron capture radius and electron
capture probability. The modified hyperbolic trajectory method is applied to the motion of the projectile positron in order
to visualize the electron capture probability as a function of the impact parameter, nonideal plasma parameter, projectile
velocity, and plasma parameters. The results show that the electron capture probability in nonideal plasmas is always greater
than that in ideal plasmas descried by the Debye-Hückel potential, i.e., the collective effect increases the electron capture probability. It is also found that the collective effect is decreased
with increasing the projectile velocity.
Received 21 January 2000 and Received in final form 27 April 2000 相似文献
2.
Young-Dae Jung 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(2):231-234
The electron-proton low energy bremsstrahlung process is investigated in a two-component plasma. The corrected Kelbg potential
taking into account the quantum effects is applied to describe the electron-proton interaction potential in a two-component
plasma. The straight-line trajectory method is applied to the motion of the projectile electron in order to investigate the
variation of the bremsstrahlung cross-section as a function of the scaled impact parameter, thermal de Broglie wavelength,
projectile energy, and photon energy. The results show that the quantum-mechanical effects decrease the bremsstrahlung cross-sections
when the de Broglie wavelength (λ) is greater than the Bohr radius (a0). It is also found that the quantum effects are important only for the region of impact parameters b < 3a
0.
Received 13 March 2001 相似文献
3.
Young-Dae Jung Jung-Sik Yoon 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(2):273-277
Orientation phenomena for direct electron-ion collisional excitations in weakly coupled plasmas () are investigated using the semiclassical curved trajectory method including the close-encounter effects. The results show
that the orientation parameters including the close-encounter effects obtained by the hyperbolic-orbit trajectory method have
maxima and minima for small impact parameter regions.
Received 18 August 1999 and Received in final form 6 December 1999 相似文献
4.
D.V. Fisher Y. Maron 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):93-111
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 相似文献
5.
Dong-Soo Shin 《Physics letters. A》2008,372(33):5458-5461
The nonthermal effects on the entanglement fidelity for the elastic electron-ion scattering are investigated in generalized Lorentzian plasmas. The dynamically screened effective potential and partial wave analysis are employed to obtain the entanglement fidelity in Lorentzian plasmas as a function of the spectral index, collision energy, and plasma parameters. It is shown that the entanglement fidelity increases with decreasing the collision energy, especially, for small Debye radii. It is also shown that the nonthermal effect enhances the entanglement fidelity in Lorentzian plasmas. In addition, it is found that the entanglement fidelity increases with an increase of the plasma temperature. 相似文献
6.
Sang-Chul Na 《Physics letters. A》2008,372(34):5605-5608
The oscillatory screening and collision-induced quantum interference effects on electron-electron collisions are investigated in dense quantum plasmas. The modified Debye-Hückel potential with the total spin states of the system is considered to obtain the differential electron-electron scattering cross section in quantum plasmas. It is shown that the electron-electron scattering cross section decreases with an increase of the quantum wave number. In addition, the minimum position of the cross section has been appeared with increasing the collision energy at the scattering angle θL=π/4. It is also found that the oscillatory screening effects strongly suppress the cross section near θL=π/4. In addition, it is found that the quantum interference effects suppress the cross section, especially, for the forward and backward scattering cases. 相似文献
7.
Hwa-Min Kim 《Physics letters. A》2007,371(4):314-317
The dynamic plasma screening and non-Maxwellian effects on elastic electron-ion collisions are investigated in generalized Lorentzian distribution plasmas. The eikonal is employed to obtain the eikonal phase as a function of the spectral index, impact parameter, collision energy, thermal energy, and Debye length. The result shows that the non-Maxwellian effect suppresses the eikonal phase. It is found that the dynamic screening effect significantly enhances the elastic collision cross section for the low thermal energy case. In addition, the eikonal collision cross section is increased by the non-Maxwellian effect. 相似文献
8.
The quantum effects on the magnetization due to the ponderomotive force are investigated in cold quantum plasmas. It is shown that the ponderomotive force of the electromagnetic wave induces the magnetization and cyclotron motion in quantum plasmas. We also show that the magnetic field would not be induced without the quantum effects in plasmas. It is also found that the quantum effect enhances the cyclotron frequency due to the ponderomotive force related to the time variation of the field intensity. In addition, it is shown that the magnetization diminishes with an increase of the frequency of the electromagnetic field. 相似文献
9.
In-Seok Chang 《Physics letters. A》2008,372(9):1498-1500
The quantum effects on the propagation of surface Langmuir oscillations are investigated in semi-bounded quantum plasmas. The specular reflection method is employed to obtain the dispersion relation of the surface Langmuir oscillations. The results show that the surface Langmuir oscillations can be propagated due to the quantum effects. It is also shown that the quantum effect enhances the propagation velocity. However, in high wave number domains, the group velocity of the propagation of surface Langmuir oscillations decreases with increasing the wave number. In addition, the electrostatic fast surface oscillating mode is found in the semi-bounded cold quantum plasmas. 相似文献
10.
Won-Seok Chang 《Physics letters. A》2007,372(1):52-55
The quantum effects on the polarization bremsstrahlung emission due to the low-energy electron-atom collisions are investigated in partially ionized dense hydrogen plasmas. The impact parameter analysis is employed to describe the motion of the projectile electron in order to investigate the variation of the bremsstrahlung emission spectrum as a function of the impact parameter, de Broglie wave length, Debye length, and radiation photon energy. The results show that the quantum effects strongly suppress the polarization bremsstarhlung emission. It is also found that the polarization bremsstarhlung emission cross section shows the maximum value at the position of the Bohr radius. It is interesting to note that the quantum effects are found to be more important than the screening effects in the polarization bremsstarhlung emission. 相似文献
11.
The magnetic field and thermal effects on the nonrelativistic electron-ion bremsstrahlung process are investigated in magnetized anisotropic plasmas. The effective electron-ion interaction potential is obtained in the presence of an external magnetic field. Using the Born approximation for the initial and final states of the projectile electron, the bremsstrahlung radiation cross section and bremsstrahlung emission rate are obtained as functions of the electron energy, radiation photon energy, magnetic field strength, plasma temperature, and Debye length. It is shown that the effects of the magnetic field enhance the bremsstrahlung radiation cross section for low plasma temperatures and, however, suppress the bremsstrahlung cross section for high plasma temperatures. It is also shown that the magnetic field effects diminish the bremsstrahlung emission rate in magnetized high temperature plasmas. 相似文献
12.
R. Riahi Ph. Teulet Z. Ben Lakhdar A. Gleizes 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(2):223-230
The weighted total cross-section (WTCS) theory is used to
calculate electron impact excitation, ionisation and dissociation cross-sections and rate coefficients of OH, H2, OH+, H2
+,
OH- and H2
- diatomic molecules in the temperature range 1500–15000 K. Calculations are performed for H2(X, B, C), OH(X, A, B),
H2
+(X), OH+(X, a, A, b, c), H2
-(X) and OH-(X)
electronic states for which Dunham coefficients are available. Rate
coefficients are calculated from WTCS assuming Maxwellian energy
distribution functions for electrons and heavy particles. One and two
temperature (θe and θg respectively for electron
and heavy particles kinetic temperatures) results are presented and fitting
parameters (a, b and c) are given for each reaction rate coefficient:
k(θ) = a (θb)exp (-c/θ). 相似文献
13.
R.K. Drampyan 《Applied physics. B, Lasers and optics》2002,75(4-5):557-561
A laser-induced electric microfield in potassium vapor partially ionized by laser radiation and placed in an external magnetic
field has been studied experimentally. It was found that the dependence of the electric field rise time on the magnetic field
strength had a peak value when the plasma frequency is equal to the Larmor frequency. This finding allows us to measure the
photoelectron density in weakly ionized potassium vapor. The results are explained in terms of a simple model that shows how
the length of the photoelectron trajectory changes with the magnetic field.
Received: 4 February 2002 / Revised version: 20 June 2002 / Published online: 25 September 2002
RID="*"
ID="*"Corresponding author. Fax: +374-32/31172, E-mail: rdramp@ipr.sci.am 相似文献
14.
Summary The temporal evolution of the electron energy distribution function (e.d.f.) in neon plasmas following a sudden change of
the electric field has been calculated by solving the time-dependent Boltzmann equation either in the presence or in the absence
of electron-electron collisions. The results show that the presence of e-e interaction does not strongly modify the global
relaxation time of e.d.f., having, however, strong consequences on the early part of the e.d.f. evolution.
Riassunto L'evoluzione temporale della funzione di distribuzione in energia degli elettroni in plasmi di neon, causata da variazioni istantanee del campo elettrico applicato, è stata calcolata risolvendo l'equazione di Boltzmann dipendente dal tempo sia in presenza sia in assenza delle collisioni elettrone-elettrone. I risultati mostrano che la presenza delle collisioni elettrone-elettrone non modifica fortemente il tempo globale di rilassamento, pur avendo forti conseguenze sull'evoluzione iniziale della funzione di distribuzione in energia degli elettroni.相似文献
15.
A. Macor F. Doveil C. Chandre G. Ciraolo R. Lima M. Vittot 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):519-530
A numerical and experimental study of a control method
aimed at channeling chaos by building barriers in phase space is
performed on a paradigm for wave-particle interaction, i.e., a
traveling wave tube. Control of chaotic diffusion is achieved by
adding small apt modifications to the system with a low additional
cost of energy. This modification is realized experimentally
through additional waves with small amplitudes. Robustness of the
method is investigated both numerically and experimentally.
An erratum to this article is available at . 相似文献
16.
17.
Young-Dae Jung 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(2):249-254
In strongly coupled plasmas, the orientation phenomena for direct excitations in electron-hydrogenic ion collisions are investigated using the ion-sphere interaction potential. For small
impact parameters, the orientation parameters have minima which correspond to the complete transitions. The target screening effects slightly increase the probability of populating the 2p-1 state.
Received: 16 December 1998 / Received in final form: 23 March 1999 相似文献
18.
Sang-Chul Na 《Physics letters. A》2009,374(2):294-296
The effects of elongated rotating dust grains on the mode transitions of the dispersion relation of the surface dust ion-acoustic waves are investigated in a semi-bounded dusty plasma. The dispersion relation of the surface dust ion-acoustic wave is obtained by the plasma dielectric function with the specular reflection boundary condition. The result shows the existence of the dust ion-acoustic resonance modes in small and large wave number regions. It is also shown that the surface wave would be propagated in intermediate wave number domains. It is interesting to note that the wave propagation domain has been diminished with an increase of the rotation frequency. 相似文献
19.
E. Floriani R. Lima R. Vilela Mendes 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(2):407-302
A stochastic representation for the solutions of the Poisson-Vlasov
equation, with several charged species, is obtained. The representation
involves both an exponential and a branching process and it provides an
intuitive characterization of the nature of the solutions and its
fluctuations. Here, the stochastic representation is also proposed as a tool
for the numerical evaluation of the solutions.
An erratum to this article is available at . 相似文献
20.
R. Plasil I. Korolov T. Kotrik P. Dohnal G. Bano Z. Donko J. Glosik 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):391-398
Experimental studies of the electron energy distribution function “EEDF” under well defined conditions in flowing afterglow
plasma, using a Langmuir probe are reported. The EEDF is measured in He2
+ and Ar+ dominated plasmas and in XeH+ and XeD+ dominated recombining plasmas. He is used as a buffer gas at medium pressures in all experiments (1600 Pa, 250 K). The deviation
of the measured EEDF from Maxwellian distribution is shown to depend on plasma composition and on the processes governing
the plasma decay. The influence of energetic electrons produced during the plasma decay on the body and tail of the EEDF is
observed. The mechanism of energy balance in afterglow plasma is discussed. 相似文献