Nonextensive Plasma Research Articles

Obliquely propagating nonextensive dust-ion-acoustic solitary waves in a dusty magnetoplasma

The basic features of obliquely propagating dust-ion-acoustic (DIA) solitary waves (SWs) in a nonextensive magnetized dusty plasma (containing non-extensive electrons, inertial ions, and negatively charged stationary dust) have been rigorously investigated. The reductive perturbation method has been employed to derive the Korteweg-de Vries equation which admits a solitary wave solution. The combined effects of electron nonextensivity and external magnetic field (obliqueness), which are found to significantly modify the basic features of the small but finite-amplitude DIA SWs, have explicitly been examined. Our present analysis can be utilized and very effective for understanding the localized nonlinear structures-the DIA SWs in different astrophysical and cosmological scenarios (viz. stellar polytropes, quark-gluon plasma, protoneutron stars, etc.).

Astrophysical naturally moderated classical positron beam interaction with nonlinear waves in nonextensive astrophysical plasmas

The positron acoustic shock and solitary wave are explored in nonextensive electron-positron-ion plasma. The plasma system under-consideration, consists of a classical positron beam, q distributed electrons and positively charged bulky ions constitute a neutralizing background. The nonlinear Korteweg-de Vries and Burger equations are derived by employing the standard reductive perturbation method. The positron acoustic wave in linear limit is also discussed for dissipative as well as nondissipative cases of nonextensive plasmas. The plasma parameters such as, the concentration of neutralizing ions background, beam velocity, temperature and q parameter of the nonextensive electrons are noticed to significantly affect the positron acoustic shock and solitary waves. Our findings may be helpful in the understanding of laboratory beam plasma interaction experiments as well as the astrophysical nonextensive plasmas interacting with positron beam.

Arbitrary amplitude dust acoustic waves in a nonextensive dusty plasma

Making use of the Sagdeev pseudo-potential approach, we derive the energy like equation for dust-acoustic (DA) solitary waves in a complex plasma having negatively charged cold dust, and electrons/ions featuring the Tsallis distribution. The effects of electron and ion nonextensivity on the DA soliton profile are examined. It is shown that depending on the strength of particle nonextensivity, our plasma model may admit compressive as well as rarefactive DA solitary waves. Our results complement previously published results on this problem.

Evolution of higher order nonlinear equation for the dust ion-acoustic waves in nonextensive plasma

There are three different types of nonlinear equations, namely, Korteweg-de Vries (K-dV), modified K-dV (mK-dV), and mixed modified K-dV (mixed mK-dV) equations, for the nonlinear propagation of the dust ion-acoustic (DIA) waves. The effects of electron nonextensivity on DIA solitary waves propagating in a dusty plasma (containing negatively charged stationary dust, inertial ions, and nonextensive q distributed electrons) are examined by solving these nonlinear equations. The basic features of mixed mK-dV (higher order nonlinear equation) solitons are found to exist beyond the K-dV limit. The properties of mK-dV solitons are compared with those of mixed mK-dV solitons. It is found that both positive and negative solitons are obtained depending on the q (nonextensive parameter).

Dust acoustic instability with non-extensive distribution

AbstractThe instability of dust acoustic waves driven by electrons and ions with different drift velocities in dusty non-extensive plasma is investigated based on the kinetic theory. The non-extensivity parameters of non-extensive distribution for three plasma components are different from each other. The instability growth rate is shown to be dependent on the non-extensivity parameters as well as on the ion--electron number density ratio. In the extensive limit (q=1), the result in Maxwellian distribution plasma is recovered. The instability growth rate is found to decrease as the population of suprathermal electrons and dust grains increases, but it enhances when the number of suprathermal ions increases and electron density decreases.

Low intensity dust ion-acoustic shock waves due to dust charge fluctuation in a nonextensive dusty plasma

The properties of low intensity dust ion acoustic shock waves are studied in a charge varying dusty plasma with nonextensive electrons. Owing to the departure from the Maxwellian electron distribution to a nonextensive one, the modified electrostatic charging of a spherical dust particle in plasma with ion streaming speed is considered. Based on the weakly nonlinear analysis, a new relationship between the low intensity localized disturbances and nonextensive electrons is derived. It is found that both strength and steepness of shock structures arise as the electrons evolve far from their thermodynamic equilibrium in such plasma with parameter ranges corresponding to Saturn’s rings. It is also shown that the ion temperature and population of electrons reduce the possibility of the formation of the shock profile.

Comment on “Debye shielding in a nonextensive plasma” [Phys. Plasmas 18, 062102 (2011)

Gougam and Tribeche [Phys. Plasmas 18, 062102 (2011)] revisit the phenomenon of Debye shielding within the theoretical framework of Tsallis statistical mechanics. The effect of electron nonextensivity on the Bohm sheath criterion is also investigated, and a modified critical Mach number is derived. However, their results are questionable, since they are based on a somewhat unjustified assumption about the parameter that specifies the width of the distribution function.

Response to “Comment on ‘Debye shielding in a nonextensive plasma’” [Phys. Plasmas 19, 034701 (2012)

We demonstrate that our used assumption concerning the Lagrange multiplier associated with the constraint on the internal energy in maximum Tsallis entropy principle, is well justified in the context of plasma physics. Moreover, it is pointed out that one has to critically analyze the commonly accepted “ion sound” formulation of the Bohm sheath criterion.

Dust-acoustic rogue waves in a nonextensive plasma

We present an investigation for the generation of a dust-acoustic rogue wave in a dusty plasma composed of negatively charged dust grains, as well as nonextensive electrons and ions. For this purpose, the reductive perturbation technique is used to obtain a nonlinear Schrödinger equation. The critical wave-number threshold k(c), which indicates where the modulational instability sets in, has been determined precisely for various regimes. Two different behaviors of k(c) against the nonextensive parameter q are found. For small k(c), it is found that increasing q would lead to an increase of k(c) until q approaches a certain value q(c), then further increase of q beyond q(c) decreases the value of k(c). For large k(c), the critical wave-number threshold k(c) is always increasing with q. Within the modulational instability region, a random perturbation of the amplitude grows and thus creates dust-acoustic rogue waves. In order to show that the characteristics of the rogue waves are influenced by the plasma parameters, the relevant numerical analysis of the appropriate nonlinear solution is presented. The nonlinear structure, as reported here, could be useful for controlling and maximizing highly energetic pulses in dusty plasmas.

Nonextensive collisioneless dust-acoustic shock waves in a charge varying dusty plasma

Nonlinear dust-acoustic (DA) shock waves are addressed in a nonextensive dusty plasma exhibiting self-consistent nonadiabatic charge variation. Our results reveal that the amplitude, strength and nature of the DA shock waves are extremely sensitive to the degree of ion nonextensivity. Significant differences in the potential function occur for very small changes in the value of the nonextensive parameter. Stronger is the ions correlation, more important is the charge variation induced nonlinear wave damping.

On a plasma having nonextensive electrons and positrons: Rogue and solitary wave propagation

Generation of nonlinear ion-acoustic waves in a plasma having nonextensive electrons and positrons has been studied. Two wave modes existing in such plasma are considered, namely solitary and rogue waves. The reductive perturbation method is used to obtain a Korteweg-de Vries equation describing the system. The latter admits solitary wave pulses, while the dynamics of the modulationally unstable wave packets described by the Korteweg-de Vries equation gives rise to the formation of rogue excitation that is described by a nonlinear Schrödinger equation. The dependence of both solitary and rogue waves profiles on the nonextensive parameter, positron-to-ion concentration ratio, electron-to-positron temperature ratio, and ion-to-electron temperature ratio are investigated numerically. The results from this work are expected to contribute to the in-depth understanding of the nonlinear excitations that may appear in nonextensive astrophysical plasma environments, such as galactic clusters, interstellar medium, etc.

Debye shielding in a nonextensive plasma

The phenomenon of Debye Shielding is revisited within the theoretical framework of the Tsallis statistical mechanics. The plasma consists of nonextensive electrons and ions. Both the effective Debye length λDq and the fall-off of the electrostatic potential Φ are considered and a parameter study conducted. Owing to electron nonextensivity, the critical Mach number derived from the modified Bohm sheath criterion may become less than unity allowing therefore ions with speed less than ion-acoustic speed to enter the sheath from the main body of the plasma. Considering the wide relevance of collective processes, our analysis may be viewed as a first step toward a more comprehensive Debye shielding and electrostatic plasma sheath in nonequilibrium plasmas.

Nonextensive electron and ion dust charging currents

The correct nonextensive electron and ion charging currents are presented for the first time based on the orbit motion limited approach. For −1<q<1, where q measures the amount of plasma nonextensivity, the nonextensive electron charging current is expressed in terms of the hypergeometric function. The variable dust charge is expressed in terms of the Lambert function and we take advantage of this transcendental function to investigate succinctly the effects of nonextensive charge carriers. The obtained formulas bring a possibility to build theories on nonlinear collective process in variable charge nonextensive dusty plasmas.

Electron-acoustic solitary waves in a nonextensive plasma

The problem of arbitrary amplitude electron-acoustic solitary waves (EASWs) in a plasma having cold fluid electrons, hot nonextensive electrons, and stationary ions is addressed. It is found that the “Maxwellianization” process of the hot nonextensive component does not favor the propagation of the EASWs. In contrast to superthermality, nonextensivity makes the electron-acoustic solitary structure less spiky. Our theoretical analysis brings a possibility to develop more refined theories of nonlinear solitary structures in astrophysical plasmas.