Lorentzian Plasma Research Articles

Effective interaction potentials and the scattering cross sections of the Lorentzian dense semiclassical plasma particles

Modified versions of the dynamic effective interaction potentials for the charged particles in dense semiclassical plasma are presented. These models consider dynamic screening, quantum mechanical effect of diffraction and particle velocity distribution function with non-Maxwellian suprathermal tail. Such distributions are well described by the so-called kappa-distribution and can be used in different space plasma and in some plasma installations where the suprathermal particles take place. Based on this modified dynamic interaction potentials the differential scattering cross sections of the electron-electron and electron-ion collisions were investigated. The obtained results for different values of the density parameter, coupling parameter and spectral index κ are presented.

Coulomb logarithm and the Dreicer field in a dense semiclassical plasma

AbstractWe obtained an expression for the Coulomb logarithm for a dense semiclassical plasma based on momentum transport cross sections using an effective interaction potential. It was shown that for densities and temperatures corresponding to the dense semiclassical plasma our results are in good agreement with MD simulations. We applied the Coulomb logarithm for the calculation of the Dreicer field. The case of dense non‐thermal Lorentzian semiclassical plasma was considered, too.

Non-thermal effects on decay of Lorentzian Trivelpiece-Gould waves

The non-thermal effects on the low-frequency ion-acoustic Trivelpiece-Gould (TG) wave are examined in a Lorentzian weakly ionized dusty plasma waveguide such as the Hanyang University Diverter Plasma Simulator-2 (DiPS-2). By using the normal mode analysis and the separation of variables, the dispersion relation and the damping modes are obtained for the low-frequency ion-acoustic TG wave in a Lorentzian weakly ionized dusty plasma waveguide. With typical conditions of DiPS-2 such as plasma density , ion-neutral collision frequency , electron temperature , and ion temperature , the following is found: 1) the magnitude of the damping rates of the low-frequency ion-acoustic TG wave in Lorentzian plasmas are always greater than those in Maxwellian plasmas; 2) the ion-acoustic TG wave for the first harmonic mode can also be existed for the shortest period of time; 3) the ion-acoustic TG wave in a smaller waveguide can be existed for a wide range of the wave number; and 4) the non-thermal character of a Lorentzian plasma enhances the anti-symmetric behavior of the damping rate for the ion-acoustic TG wave.

Kinetic study of electrostatic modes in a Lorentzian Electron-Positron-Ion (EPI) plasma

The propagation and Landau damping of Langmuir Waves (LWs) and Ion-Acoustic Waves (IAWs) in Electron-Positron-Ion (EPI) plasma are investigated using Kinetic theory approach, with all the species to be Kappa or Lorentzian distributed. We observed that the Landau damping rates γ(κ) of Langmuir waves and IAWs in Lorentzian EPI plasma strongly depend upon the spectral index κ i.e., non-thermality parameter, wave number k, the positron temperature T p and the positron concentration or number density n p . The Landau damping γ(κ) of Langmuir waves was found to be increased with higher positron temperatures T p , whereas, that of IAWs was found to increase with lower positron temperatures T p . Moreover, it was observed γ(κ) of LWs shows a decrease with increase in positron concentration while γ(κ) of IAWs tends to increase.

ISSDE: A Monte Carlo implicit simulation code based on Stratonovich SDE approach of Coulomb collision* *Project supported by the National MCF Energy R&D Program of China (Grant No. 2018YFE0304100), the National Key Research and Development Program of China (Grant Nos. 2016YFA0400600, 2016YFA0400601, and 2016YFA0400602), and the National Natural Science Foundation of China (Grant Nos. NSFC- 11805273 and NSFC-11905220).

A Monte Carlo implicit simulation program, Implicit Stratonovich Stochastic Differential Equations (ISSDE), is developed for solving stochastic differential equations (SDEs) that describe plasmas with Coulomb collision. The basic idea of the program is the stochastic equivalence between the Fokker–Planck equation and the Stratonovich SDEs. The splitting method is used to increase the numerical stability of the algorithm for dynamics of charged particles with Coulomb collision. The cases of Lorentzian plasma, Maxwellian plasma and arbitrary distribution function of background plasma have been considered. The adoption of the implicit midpoint method guarantees exactly the energy conservation for the diffusion term and thus improves the numerical stability compared with conventional Runge–Kutta methods. ISSDE is built with C++ and has standard interfaces and extensible modules. The slowing down processes of electron beams in unmagnetized plasma and relaxation process in magnetized plasma are studied using the ISSDE, which shows its correctness and reliability.

Study of two stream instabilities in Lorentzian dusty plasma

Two-stream instabilities in an unmagnetized Lorentzian dusty plasma have been investigated using a kinetic theory approach. The occurrence of this instability is discussed in the case of three different plasma wave modes. The first one is the instability of the Langmuir wave driven by streaming suprathermal electrons. The second one is the instability of the dust ion-acoustic wave driven by streaming suprathermal electrons, ions, and dust grains. The last one is concerned with the instability of the dust acoustic wave driven by streaming suprathermal dust grains. Using the Lorentzian kappa velocity distribution function, the real and imaginary frequencies of these waves have been derived analytically. The effect of the suprathermal particle density and the streaming particle density on the real and imaginary frequencies of the waves is examined numerically.

Effect of Coulomb Focusing on the Electron–Atom Bremsstrahlung Cross Section for Tungsten and Iron in Nonthermal Lorentzian Plasmas

The Coulomb focusing effect on the electron–atom bremsstrahlung spectrum is investigated in nonthermal Lorentzian plasmas. The universal expression of the cross section of nonrelativistic electron–atom bremsstrahlung process is obtained by the solution of the Thomas-Fermi equation with the effective atomic charge. The effective Coulomb focusing for the electron–atom bremsstrahlung cross section near the threshold domain is also investigated by adopting the modified Elwert-Sommerfeld factor with the mean effective charge for the bremsstrahlung process. In addition, the bremsstrahlung emission rates are obtained by considering encounters between nonthermal electrons and atoms such as Fe and W atoms. We found that the bremsstrahlung emission rates for nonthermal electron–atoms are lower than those for thermal plasmas. Various nonthermal effects on the bremsstrahlung emission rates in Lorentzian plasmas are also discussed.

The study of nonlinear dust acoustic wave propagation in a Lorentzian dusty Vlasov plasma in the presence of negative ions

Applying a reductive perturbation analysis in the Vlasov–Poisson model, a Korteweg–de Vries (KdV) equation has been derived for small amplitude dust acoustic waves in a Lorentzian dusty plasma composed of electrons, positive ions, negative ions and charged dust particles. In this paper, two models have been considered, one containing negative and the other containing positive grain charges. Nonlinear propagation of dust acoustic waves in both cases of negative and positive grain charges is governed by KdV equation which gives dust acoustic soliton solution. This dust acoustic soliton solution is rarefied for negative equilibrium dust charge and compressive for positive equilibrium dust charge. Our investigation also shows that the amplitude of dust acoustic soliton in both cases is less than their amplitudes if they are obtained by fluid theory. Thus, our kinetic model captures the nonlinear damping effect of dust acoustic soliton which is absent in fluid theory. The effect of kappa index and dust temperature on the soliton amplitude and width are also studied.

Resonant flow instability of space-charge waves in self-gravitating Lorentzian dusty plasma columns

The dispersion characteristics and the resonant instability mode of the space-charge wave are investigated in a streaming Lorentzian dusty plasma column by using the normal mode analysis. The result shows that the non-thermal character of the Lorentzian cylindrical dusty plasma enhances the unstable property of the space-charge wave due to the beam–plasma interaction. It is found that the resonant growth rates of the space-charge wave increase with an increase of the harmonic-order of the root of the Bessel function. It is also found that the influence of the self-gravitation enhances the resonant growth rate of the space-charge wave of the Lorentzian cylindrical dusty plasma. In addition, it is found the resonant growth rate decreases with an increase of the radius of the dusty plasma column. The variation of the resonant instability mode due to the non-thermal character and geometric effects is also discussed.

Astronomical Data of Atomic Shannon Entropies in Astrophysical Lorentzian Plasmas

Abstract The nonthermal effects on the variation of the Shannon entropy for the atomic states are investigated in astrophysical Lorentzian plasmas. The screened atomic wave functions, energy eigenvalues, and effective screening lengths for the hydrogen atom in Lorentzian plasmas are obtained by the Rayleigh–Ritz method. The Shannon entropies for the ground and excited states in astrophysical Lorentzian plasmas are also obtained as functions of the spectral index, effective screening lengths, and plasma parameters including the radial and angular parts. It is shown that the nonthermal characters of the Lorentzian plasma suppresses the entropy changes in the ground state as well as in the excited states. In addition, it is found that the entropy change in excited states is more effective than that in the ground state in Lorentzian astrophysical plasmas. Moreover, it is shown that the entropy change is independent of the magnetic quantum number of the state because the angular parts of Shannon entropy are unchanged due to the influence of nonthermal character and plasma screening in astrophysical Lorentzian plasmas.

Nonlinear dust-acoustic wave propagation in a Lorentzian dusty plasma in presence of negative ions

In this paper we have studied the effect of the density and temperature of negative ions on the nonlinear dust-acoustic wave propagation in a Lorentzian dusty plasma. We have considered both adiabatic and non-adiabatic dust charge variation. The presence of both low and high populations of negative ions are considered. Separate models have been developed because the two populations give rise to opposite polarity of grain charges. In both models electrons are assumed to follow a kappa velocity distribution while the positive and negative ions satisfy a Maxwellian velocity distribution. Adiabatic dust charge variation shows the propagation of a dust-acoustic soliton in cases of both a high and low population of negative ions whose amplitude depends on the negative ion temperature and negative ion density. On the other hand, non-adiabatic dust charge variation generates a stable oscillatory dust-acoustic shock when the negative ion population is low. An unstable potential has been predicted from this analysis when the negative ion population is high and the dust charge variation is non-adiabatic.

Study of the Characteristics of Dust Acoustic Solitary Waves and Dust Acoustic Shock Waves in Electron Free Dusty Space Plasma

A theoretical investigation has been done for the study of dust acoustic solitary waves and dust acoustic shock waves propagating in an unmagnetized, collisionless Lorentzian dusty plasma considering adiabatic and non-adiabatic dust charge variation. Plasma under consideration is composed of inertialess Lorentzian positive and negative ions along with inertial positively charged dust grains. Such dust grains are charged by the flow of positive ion and negative ion current over the grain surface. Adiabatic grain charge variation shows the existence of compressive soliton whose amplitude decreases and width increases with increasing number of suprathermal particles. Non-adiabatic dust charge variation is concerned with the propagation of monotonic dust acoustic shock waves which do not loose monotonicity even when a number of suprathermal particles are very large.

Growth rates of space-charge waves in a Lorentzian plasma waveguide

The non-thermal effects on the growth rate of the space charge wave are investigated in a Lorentzian dustyplasma-filled waveguide by employing the normal mode analysis and the method of separation of variables.The growth rate and the real frequency of the space charge wave are obtained as functions of the harmonicroots of the Bessel function and the spectral index of the Lorentzian plasma. It is shown that the non-thermaleffect suppresses the real frequency of the space-charge wave. In addition, the scaled growth rate decreaseswith an increase of the spectral index. Hence, we have found that the growth rates in non-thermal plasmas arealways smaller than those in thermal plasmas. It was shown that the influence of non-thermal character plays acrucial role on the space-charge wave due to the coupling interaction of the streaming ions with non-thermalelectrons in a Lorentzian dusty plasma waveguide. These results would provide useful information on the nonthermaleffects on the space-charge wave in non-Maxwellian multi-component plasma waveguides.

Characteristics of nonlinear dust acoustic waves in a Lorentzian dusty plasma with effect of adiabatic and nonadiabatic grain charge fluctuation

In this paper, characteristics of small amplitude nonlinear dust acoustic wave have been investigated in a unmagnetized, collisionless, Lorentzian dusty plasma where electrons and ions are inertialess and modeled by generalized Lorentzian Kappa distribution. Dust grains are inertial and equilibrium dust charge is negative. Both adiabatic and nonadiabatic fluctuation of charges on dust grains have been taken under consideration. For adiabatic dust charge variation reductive perturbation analysis gives rise to a KdV equation that governs the nonlinear propagation of dust acoustic waves having soliton solutions. For nonadiabatic dust charge variation nonlinear propagation of dust acoustic wave obeys KdV-Burger equation and gives rise to dust acoustic shock waves. Numerical estimation for adiabatic grain charge variation shows the existence of rarefied soliton whose amplitude and width varies with grain charges. Amplitude and width of the soliton have been plotted for different electron Kappa indices keeping ion velocity distribution Maxwellian. For non adiabatic dust charge variation, ratio of the coefficients of Burger term and dispersion term have been plotted against charge fluctuation for different kappa indices. All these results approach to the results of Maxwellian plasma if both electron and ion kappa tends to infinity.

Resonant Compton Scattering of Photons by Helium Atoms in Lorentzian Astrophysical Plasmas

We investigate the effects of Lorentzian astrophysical plasmas on resonant Compton scattering of photons by the helium ground and excited states. The bound-excited states energies in the plasma environments are obtained by using highly correlated exponential wave functions in the framework of Ritz variational method. The resonance Compton scattering cross sections in Lorentzian plasmas between the \(\hbox {1s}^{2}{\,}^{1}\hbox {S}\) and 1s2p \(^{1}\hbox {P}\), 1s2s \(^{1}\hbox {S}\) and 1s3p \(^{1}\hbox {P}\), 1s3s \(^{1}\hbox {S}\) and 1s3d \(^{1}\hbox {D}\) states are reported as a function of the spectral index and plasma parameter. The nonthermal character of the Lorentzian plasmas shows interesting features on the resonant Compton scattering cross sections.

Transport coefficients of a relativistic plasma.

In this work, a self-consistent transport theory for a relativistic plasma is developed. Using the notation of Braginskii [S. I. Braginskii, in Reviews of Plasma Physics, edited by M. A. Leontovich (Consultants Bureau, New York, 1965), Vol. 1, p. 174], we provide semianalytical forms of the electrical resistivity, thermoelectric, and thermal conductivity tensors for a Lorentzian plasma in a magnetic field. This treatment is then generalized to plasmas with arbitrary atomic number by numerically solving the linearized Boltzmann equation. The corresponding transport coefficients are fitted by rational functions in order to make them suitable for use in radiation-hydrodynamic simulations and transport calculations. Within the confines of linear transport theory and on the assumption that the plasma is optically thin, our results are valid for temperatures up to a few MeV. By contrast, classical transport theory begins to incur significant errors above k_{B}T∼10 keV, e.g., the parallel thermal conductivity is suppressed by 15% at k_{B}T=20 keV due to relativistic effects.

The first radial-mode Lorentzian Landau damping of dust acoustic space-charge waves

The dispersion properties and the first radial-mode Lorentzian Landau damping of a dust acoustic space-charge wave propagating in a cylindrical waveguide dusty plasma which contains nonthermal electrons and ions are investigated by employing the normal mode analysis and the method of separation of variables. It is found that the frequency of dust acoustic space-charge wave increases as the wave number increases as well as the radius of cylindrical plasma does. However, the nonthermal property of the Lorentzian plasma is found to suppress the wave frequency of the dust acoustic space-charge wave. The Landau damping rate of the dust acoustic space-charge wave is derived in a cylindrical waveguide dusty plasma. The damping of the space-charge wave is found to be enhanced as the radius of cylindrical plasma and the nonthermal property increase. The maximum Lorentzian Landau damping rate is also found in a cylindrical waveguide dusty plasma. The variation of the wave frequency and the Landau damping rate due to the nonthermal character and geometric effects are also discussed.

Ion wake field effects on the dust-ion-acoustic surface mode in a semi-bounded Lorentzian dusty plasma

The dispersion relation for the dust ion-acoustic surface waves propagating at the interface of semi-bounded Lorentzian dusty plasma with supersonic ion flow has been kinetically derived to investigate the nonthermal property and the ion wake field effect. We found that the supersonic ion flow creates the upper and the lower modes. The increase in the nonthermal particles decreases the wave frequency for the upper mode whereas it increases the frequency for the lower mode. The increase in the supersonic ion flow velocity is found to enhance the wave frequency for both modes. We also found that the increase in nonthermal plasmas is found to enhance the group velocity of the upper mode. However, the nonthermal particles suppress the lower mode group velocity. The nonthermal effects on the group velocity will be reduced in the limit of small or large wavelength limit.

Landau damping of the dust-acoustic surface waves in a Lorentzian dusty plasma slab

Landau damping of a dust-acoustic surface wave propagating at the interfaces of generalized Lorentzian dusty plasma slab bounded by a vacuum is kinetically derived as the surface wave displays the symmetric and the anti-symmetric mode in a plasma slab. In the limiting case of small scaled wave number, we have found that Landau damping is enhanced as the slab thickness is increased. In particular, the damping of anti-symmetric mode is much stronger for a Lorentzian plasma than for a Maxwellian plasma. We have also found that the damping is more affected by superthermal particles in a Lorentzian plasma than by a Maxwellian plasma for both of the symmetric and the anti-symmetric cases. The variations of Landau damping with various parameters are also discussed.

Non-thermal Dupree diffusivity and shielding effects on atomic collisions in astrophysical turbulent plasmas

The influence of non-thermal Dupree turbulence and the plasma shielding on the electron–ion collision is investigated in astrophysical non-thermal Lorentzian turbulent plasmas. The second-order eikonal analysis and the effective interaction potential including the Lorentzian far-field term are employed to obtain the eikonal scattering phase shift and the eikonal collision cross section as functions of the diffusion coefficient, impact parameter, collision energy, Debye length and spectral index of the astrophysical Lorentzian plasma. It is shown that the non-thermal effect suppresses the eikonal scattering phase shift. However, it enhances the eikonal collision cross section in astrophysical non-thermal turbulent plasmas. The effect of non-thermal turbulence on the eikonal atomic collision cross section is weakened with increasing collision energy. The variation of the atomic cross section due to the non-thermal Dupree turbulence is also discussed.