Two-component Plasma Research Articles

Stationary solutions of the Vlasov–Poisson system for two-component plasma under an external magnetic field in a half-space

We consider the first mixed problem for the Vlasov–Poisson equations with an external magnetic field in a half-space. This problem describes the evolution of the density distributions of ions and electrons in a high temperature plasma with a fixed potential of electric field on a boundary. For a sufficiently large induction of external magnetic field there are constructed stationary solutions supported on some distance from the hyperplane x 1 = 0.

Suzakuanalysis of the supernova remnant G306.3−0.9 and the gamma-ray view of its neighbourhood

We present an investigation of the supernova remnant (SNR) G306.3$-$0.9 using archival multi-wavelength data. The Suzaku spectra are well described by two-component thermal plasma models: The soft component is in ionization equilibrium and has a temperature $\sim$0.59 keV, while the hard component has temperature $\sim$3.2 keV and ionization time-scale $\sim$$2.6\times10^{10}$ cm$^{-3}$ s. We clearly detected Fe K-shell line at energy of $\sim$6.5 keV from this remnant. The overabundances of Si, S, Ar, Ca, and Fe confirm that the X-ray emission has an ejecta origin. The centroid energy of the Fe-K line supports that G306.3$-$0.9 is a remnant of a Type Ia supernova (SN) rather than a core-collapse SN. The GeV gamma-ray emission from G306.3$-$0.9 and its surrounding were analyzed using about 6 years of Fermi data. We report about the non-detection of G306.3$-$0.9 and the detection of a new extended gamma-ray source in the south-west of G306.3$-$0.9 with a significance of $\sim$13$\sigma$. We discuss several scenarios for these results with the help of data from other wavebands to understand the SNR and its neighborhood.

Dynamic properties of the energy loss of multi-MeV charged particles traveling in two-component warm dense plasmas.

The energy loss of multi-MeV charged particles moving in two-component warm dense plasmas (WDPs) is studied theoretically beyond the random-phase approximation. The short-range correlations between particles are taken into account via dynamic local field corrections (DLFC) in a Mermin dielectric function for two-component plasmas. The mean ionization states are obtained by employing the detailed configuration accounting model. The Yukawa-type effective potential is used to derive the DLFC. Numerically, the DLFC are obtained via self-consistent iterative operations. We find that the DLFC are significant around the maximum of the stopping power. Furthermore, by using the two-component extended Mermin dielectric function model including the DLFC, the energy loss of a proton with an initial energy of ∼15MeV passing through a WDP of beryllium with an electronic density around the solid value n_{e}≈3×10^{23}cm^{-3} and with temperature around ∼40 eV is estimated numerically. The numerical result is reasonably consistent with the experimental observations [A. B. Zylsta etal., Phys. Rev. Lett. 111, 215002 (2013)PRLTAO0031-900710.1103/PhysRevLett.111.215002]. Our results show that the partial ionization and the dynamic properties should be of importance for the stopping of charged particles moving in the WDP.

Vlasov–Poisson equations for a two-component plasma in a half-space

The Vlasov–Poisson equations for a two-component high-temperature plasma with an external magnetic field in a half-space are considered. The electric field potential satisfies the Dirichlet condition on the boundary, and the initial density distributions of charged particles satisfy the Cauchy conditions. Sufficient conditions for the induction of the external magnetic field and the initial charged-particle density distributions are obtained that guarantee the existence of a classical solution for which the supports of the charged-particle density distributions are located at some distance from the boundary.

Current evolution and plasma density space distribution in the reflex discharge with ring cathodes

In this paper the numerical model of direct current gas discharge in drift-diffusion approximation is considered. For two-component plasma the processes of the gas discharge development in the reflex geometry with ring cathodes at a helium pressure of 35 mTorr are studied. We investigate the influence of: (a) the boundary conditions on the dielectric, (b) the electron temperature and (c) the coefficient of the secondary ion-electron emission on the I–U curve of the discharge. In a magnetic field of 50 Gauss the impact of the discharge voltage U = 300–700 V on the evolutionary process of the discharge is examined. The effect of diffusion on maintaining steady state discharge is researched. The parameters of the existence of a high-current (tens of μA) and low voltage (tens of mA) discharge modes are defined.

A perturbative correction for electron-inertia in magnetized sheath structures

We propose a hydrodynamic model to study the equilibrium properties of planar plasma sheaths in two-component quasi-neutral magnetized plasmas. It includes weak but finite electron-inertia incorporated via a regular perturbation of the electronic fluid dynamics only relative to a new smallness parameter, δ, assessing the weak inertial-to-electromagnetic strengths. The zeroth-order perturbation around δ leads to the usual Boltzmann distribution law, which describes inertialess thermalized electrons. The forthwith next higher-order yields the modified Boltzmann law describing the putative lowest-order electron-inertial correction, which is applied meticulously to derive the local Bohm criterion for sheath formation. It is found to be influenced jointly by electron-inertial corrective effects, magnetic field and field orientation relative to the bulk plasma flow. We establish that the mutualistic action of electron-inertia amid gyro-kinetic effects slightly enhances the ion-flow Mach threshold value (typically, M i0 ⩾ 1.140), against the normal value of unity, confrontationally towards the sheath entrance. A numerical illustrative scheme is methodically constructed to see the parametric dependence of the new sheath properties on diverse problem arguments. The merits and demerits are highlighted in the light of the existing results conjointly with clear indication to future ameliorations.

Ion-acoustic rogue waves in magnetized solar wind plasma with nonextensive electrons

Abstract Ion-acoustic rogue waves are investigated in a two-component magnetized solar wind plasma, composed of positively charged fluid ions, as well as nonextensive electrons. Typical solar wind plasmas parameters are used. It is shown that the wave number domain for the onset of ion-acoustic modulational instability enlarges as the electrons evolve towards their thermal equilibrium. Interestingly, we show that as the solar wind plasma expands far out from the sun, the wave amplitude increases and the IA rogue wave concentrates therefore a significant amount of energy. Our investigation may be of wide relevance to astronomers and space scientists working on the solar wind and interstellar plasmas.

Torsional Alfvén and slow magnetoacoustic waves generated by a plasma in a magnetic field

A new effect has been experimentally revealed: a sequence of flashes of a two-component laser plasma creates a flow containing torsional Alfven and slow magnetoacoustic waves in a magnetic flux tube.

Electrostatic fluctuations in a magnetized two-component plasma with q-nonextensive electrons and thermal ions

The effect of ion temperature on nonlinear low frequency electrostatic potential structures is studied in a two component magnetized plasma with q-nonextensive hot electrons. The standard Sagdeev pseudo-potential approach is used to investigate the existence of ion acoustic solitons and double layers and their dependence on finite ion temperature. Only solitons are found to exist, with the amplitude decreasing as the ion temperature increases. For parameters typical of the auroral plasma, our model yields a soliton electric field amplitude of 22 mV/m, which is within the range measured by satellites, and as such can be helpful in understanding the electrostatic fluctuations phenomena in space environments.

Large Deviations for the Two-Dimensional Two-Component Plasma

We derive a large deviations principle for the two-dimensional two-component plasma in a box. As a consequence, we obtain a variational representation for the free energy, and also show that the macroscopic empirical measure of either positive or negative charges converges to the uniform measure. An appendix, written by Wei Wu, discusses applications to the supercritical complex Gaussian multiplicative chaos.

Fourth Moment Sum Rule for the Charge Correlations of a Two-Component Classical Plasma

We consider an ionic fluid made with two species of mobile particles carrying either a positive or a negative charge. We derive a sum rule for the fourth moment of equilibrium charge correlations. Our method relies on the study of the system response to the potential created by a weak external charge distribution with slow spatial variations. The induced particle densities, and the resulting induced charge density, are then computed within density functional theory, where the free energy is expanded in powers of the density gradients. The comparison with the predictions of linear response theory provides a thermodynamical expression for the fourth moment of charge correlations, which involves the isothermal compressibility as well as suitably defined partial compressibilities. The familiar Stillinger-Lovett condition is also recovered as a by-product of our method, suggesting that the fourth moment sum rule should hold in any conducting phase. This is explicitly checked in the low density regime, within the Abe-Meeron diagrammatical expansions. Beyond its own interest, the fourth-moment sum rule should be useful for both analyzing and understanding recently observed behaviours near the ionic critical point.

Nonlinear low frequency electrostatic structures in a magnetized two-component auroral plasma

Finite amplitude nonlinear ion-acoustic solitons, double layers, and supersolitons in a magnetized two-component plasma composed of adiabatic warm ions fluid and energetic nonthermal electrons are studied by employing the Sagdeev pseudopotential technique and assuming the charge neutrality condition at equilibrium. The model generates supersoliton structures at supersonic Mach numbers regime in addition to solitons and double layers, whereas in the unmagnetized two-component plasma case only, soliton and double layer solutions can be obtained. Further investigation revealed that wave obliqueness plays a critical role for the evolution of supersoliton structures in magnetized two-component plasmas. In addition, the effect of ion temperature and nonthermal energetic electron tends to decrease the speed of oscillation of the nonlinear electrostatic structures. The present theoretical results are compared with Viking satellite observations.

The stationary non-equilibrium plasma of cosmic-ray electrons and positrons

The statistical properties of the two-component plasma of cosmic-ray electrons and positrons measured by the AMS-02 experiment on the International Space Station and the HESS array of imaging atmospheric Cherenkov telescopes are analyzed. Stationary non-equilibrium distributions defining the relativistic electron–positron plasma are derived semi-empirically by performing spectral fits to the flux data and reconstructing the spectral number densities of the electronic and positronic components in phase space. These distributions are relativistic power-law densities with exponential cutoff, admitting an extensive entropy variable and converging to the Maxwell–Boltzmann or Fermi–Dirac distributions in the non-relativistic limit. Cosmic-ray electrons and positrons constitute a classical (low-density high-temperature) plasma due to the low fugacity in the quantized partition function. The positron fraction is assembled from the flux densities inferred from least-squares fits to the electron and positron spectra and is subjected to test by comparing with the AMS-02 flux ratio measured in the GeV interval. The calculated positron fraction extends to TeV energies, predicting a broad spectral peak at about 1 TeV followed by exponential decay.

Potential distribution around a test charge in a positive dust-electron plasma

The electrostatic potential caused by a test-charge particle in a positive dust-electron plasma is studied, accounting for the dust-charge fluctuations associated with ultraviolet photoelectron and thermionic emissions. For this purpose, the set of Vlasov–Poisson equations coupled with the dust charging equation is solved by using the space–time Fourier transform technique. As a consequence, a modified dielectric response function is obtained for dust-acoustic waves in a positive dust-electron plasma. By imposing certain conditions on the velocity of the test charge, the electrostatic potential is decomposed into the Debye–H¨uckel (DH), wake-field (WF), and far-field (FF) potentials that are significantly modified in the limit of a large dust-charge relaxation rate both analytically and numerically. The results can be helpful for understanding dust crystallization/coagulation in twocomponent plasmas, where positively charged dust grains are present.

Dynamic Stark broadening of Lyman-α

Calculating lineshapes of atomic radiative transitions broadened by plasma is a complex problem lacking a general analytic solution, and several models have been suggested to treat it. Lyman-α is the simplest transition; paradoxically however, calculating the broadening of this spectral line in plasma results in a significant spread between different models. Here, we argue that the quasistatic broadening regime is never realized for the line core in a one-component plasma; instead, the broadening due to either electrons or ions alone evolves from the impact regime to another regime, also dynamical in nature. In the latter (referred to here as ‘rotational’ broadening), the linewidth only depends on the typical frequency of the plasma microfields and is independent of both the microfield magnitudes and the atomic properties of the transition. We also demonstrate that rotational broadening is asymptotically reached in the high-density/low-temperature limit by other transitions with an unshifted central component, such as the Balmer-α line. A simple expression is suggested interpolating between the two asymptotic regimes, applicable to broadening due to electrons and ions alike. The treatment is further extended to realistic two-component plasmas. Comparison to results of accurate computer simulations shows a good agreement over a very large range of plasma parameters, both for the case of one- and two-component plasmas.

Calculating phase equilibrium properties of plasma pseudopotential model using hybrid Gibbs statistical ensemble Monte-Carlo technique

Earlier a two-component pseudopotential plasma model, which we called a “shelf Coulomb” model has been developed. A Monte-Carlo study of canonical NVT ensemble with periodic boundary conditions has been undertaken to calculate equations of state, pair distribution functions, internal energies and other thermodynamics properties of the model. In present work, an attempt is made to apply so-called hybrid Gibbs statistical ensemble Monte-Carlo technique to this model. First simulation results data show qualitatively similar results for critical point region for both methods. Gibbs ensemble technique let us to estimate the melting curve position and a triple point of the model (in reduced temperature and specific volume coordinates): T* ≈ 0.0476, v* ≈ 6 × 10-4.

A generalized two-fluid model of plasma sheath equilibrium structure

A generalized two-fluid model to study the equilibrium structure of plasma sheath in a normal two-component plasma with all the possible viscoelastic effects taken into account is methodologically constructed for the first time. It includes weak but finite (lowest-order) inertial correction of the plasma thermal electrons. The Bohm condition for the sheath formation in viscoelastically modified form is strategically derived and methodically tested for accuracy in exactly reproducing the earlier well-known results in idealized normal plasma conditions. A systematic strategy of numerical illustrations is presented to investigate the main characteristic features of the sheath structure. It is demonstrated that the sheath evolution is considerably affected by both plasma viscoelasticity and the active electron inertial dynamics. The results can be extensively useful to explore realistic plasma boundary-wall interaction processes via cross-border effects in the presence of correlative coordination encountered in diversified laboratory, starspace and other astrophysical environments.

Quantum diffraction and shielding effects on the low-energy electron-ion bremsstrahlung in two-component semiclassical plasmas

The quantum diffraction and shielding effects on the low-energy bremsstrahlung process are investigated in two-component semiclassical plasmas. The impact-parameter analysis with the micropotential taking into account the quantum diffraction and shielding effects is employed to obtain the electron-ion bremsstrahlung radiation cross section as a function of the de Broglie wavelength, density parameter, impact parameter, photon energy, and projectile energy. The result shows that the influence of quantum diffraction and shielding strongly suppresses the bremsstrahlung radiation spectrum in semiclassical plasmas. It is found that the quantum diffraction and shielding effects have broaden the photon emission domain. It is also found that the photon emission domain is almost independent of the radiation photon energy. In addition, it is found that the influence of quantum diffraction and shielding on the bremsstrahlung spectrum decreases with an increase of the projectile energy. The density effect on the electron-ion bremsstrahlung cross section is also discussed.

Evaluation of the operational parameters for NBI-driven fusion in low-gain tokamaks with two-component plasma

Low gain (Q ~ 1) fusion plasma systems are of interest for concepts of fusion–fission hybrid reactors. Operational regimes of large modern tokamaks are close to Q ≈ 1. Therefore, they can be considered as prototypes of neutron sources for fusion–fission hybrids. Powerful neutral beam injection (NBI) can support the essential population of fast particles compared with the Maxwellial population. In such two-component plasma, fusion reaction rate is higher than for Maxwellian plasma. Increased reaction rate allows the development of relatively small-size and relatively inexpensive neutron sources. Possible operating regimes of the NBI-heated tokamak neutron source are discussed. In a relatively compact device, the predictions of physics of two-component fusion plasma have some volatility that causes taking into account variations of the operational parameters. Consequent parameter ranges are studied. The feasibility of regimes with Q ≈ 1 is shown for the relatively small and low-power system. The effect of NBI fraction in total heating power is analyzed.

Quantum characteristics of occurrence scattering time in two-component non-ideal plasmas

The quantum diffraction and plasma screening effects on the occurrence time for the collision process are investigated in two-component non-ideal plasmas. The micropotential model taking into account the quantum diffraction and screening with the eikonal analysis is employed to derive the occurrence time as functions of the collision energy, density parameter, Debye length, de Broglie wavelength, and scattering angle. It is shown that the occurrence time for forward scattering directions decreases the tendency of time-advance with increasing scattering angle and de Broglie wavelength. However, it is found that the occurrence time shows the oscillatory time-advance and time-retarded behaviors with increasing scattering angle. It is found that the plasma screening effect enhances the tendency of time-advance on the occurrence time for forward scattering regions. It is also shown the quantum diffraction effect suppresses the occurrence time advance for forward scattering angles. In addition, it is shown that the occurrence time advance decreases with an increase of the collision energy.