Effect Of Dust Charge Fluctuation Research Articles

Effect of dust grains on the parametric coupling of a lower hybrid wave driven ion cyclotron wave in a tokamak plasma

In this article, the effect of dust charge fluctuations on the parametric upconversion of a lower hybrid wave into an ion cyclotron wave and a side band wave in a two-ion species tokamak plasma is studied. When the oscillatory velocity of plasma electrons is a few percent of the sound velocity, the lower hybrid wave becomes unstable and decays into two modes: an ion cyclotron wave mode and a low frequency lower hybrid side band wave. Furthermore, a ponderomotive force by a lower hybrid pump and a side band wave is exerted on the existing electrons, which drives the ion cyclotron decay mode. The presence of negatively charged dust grains and their shape, size, radius, and density influence the instability. The growth rate of instability is calculated by considering typical existing D–T (Deuterium–Tritium) dusty plasma parameters, and it is observed that the growth rate increases with the relative density of dust grains, number density of dust grains, oscillatory velocity of electrons, and amplitude of pump waves. However, the normalized growth rate increases with the unstable wave frequency, and it also increases as we increase the ratio of deuterium to tritium density. Here, the growth rate decreases with the increase in the size of dust grains and electron cyclotron frequency. The theoretical results summarized in the present study are able to efficiently elaborate the complexity produced in plasma properties in a tokamak due to the dust–plasma interactions, which are briefly discussed here.

Kinetic theory of effect of dust charge fluctuations on the parametric decay of lower hybrid wave instability by relativistic runaway electrons in tokamak

Dust charge fluctuation effect on the parametric decay of lower hybrid wave instability by relativistic runaway electrons is studied in a tokamak using kinetic treatment. Parametric upconversion of lower hybrid pump waves into relativistic runaway electron mode and upper sideband mode is described. A ponderomotive force is exerted on the runaway electrons by lower hybrid pump wave possessing large amplitude and upper sideband wave, which drives the runaway electron mode. The coupling of the oscillatory velocity of electrons with density perturbations produces nonlinear density perturbations on the upper sideband frequency. As a result, runaway generation is enhanced by a lower hybrid wave and the growth rate of the instability is measured as the square of the amplitude of the pump wave. Moreover, the presence of dust charge fluctuations and their number density in the tokamak have an appreciable effect on the growth rate of lower hybrid wave instabilities, which in turn affects the actual performance of the ITER due to the potential safety and operational issues.

Particle-in-cell simulation of the effect of dust charge fluctuation on ion acoustic waves in a dusty plasma

A new hybrid-particle-in-cell (PIC)-Monte Carlo Collision (h-PIC-MCC) algorithm is presented here. The code correctly simulates the damping of ion acoustic wave due to dust charge fluctuation in a dusty plasma along with other kinetic effects such as Landau damping. In the model, on event of a collision between a charged particle and a dust particle, a randomised probability determines whether the charged particle is absorbed by the dust with the collision cross section being determined dynamically by the overall interaction scenario. We find that this method is versatile enough as it can also include the size and mass distribution for the dust particles, in addition to the charged species dynamics. As such, it can be adopted to study numerous phenomena that occur in diverse dusty plasma environments. We believe that the damping of the ion acoustic wave through dust charge fluctuation is being demonstrated, for the first time, with a PIC code, in this work.

New method for rekindling the explosive waves in Maxwellian space plasmas

Our interest is to study the nonlinear wave phenomena in complex plasma constituents with Maxwellian electrons and ions. The main aim is to use a new method known as the (G′/G) method to exhibit the effects of dust charge fluctuations on the evolution of nonlinear waves. The coherent features of the shock and solitary waves along with the generation of high-energy waves have been amplified through the solution of the Korteweg–de Vries–Burgers equation, and the different natures of the waves were found successfully. Results are discussed graphically with the thoughtful choice of typical plasma parameters from different space plasma environments, exactly those found in cosmic dusty plasmas laden in ionospheric auroral region, radial spokes of Saturn’s rings, planetary nebulae and solar F-corona region. All conclusions are in good accordance with the actual occurrences and could be of interest to further investigations of space. Moreover, the applicability of the present method is hoped to be a great enhancement by its use as ingenious mechanism used to evaluate the soliton dynamics and Burgers shock waves.

The effect of dust grains on the Weibel instability in presence of large amplitude electrostatic waves

Theoretical investigations on the effect of dust charge fluctuations on Weibel instability in a plasma, with an electron beam in the presence of large amplitude electrostatic Langmuir waves, have been performed. It is observed that the dust charge fluctuations enhance the growth rate of electromagnetic (EM) perturbations. An increase in the electron to ion temperature ratio amplifies the EM perturbations, leading to an enhanced magnetic field due to Weibel instability. It has been found that the growth rate of Weibel instability strongly depends on the dust grain size for different values of ion to electron density ratio δm. Moreover, the electron to ion temperature ratio also destabilizes the Weibel instability.

Effect of Dust Charge Fluctuation on Ion Acoustic Waves in a Plasma with Nonextensive Electrons

The linear dispersion for ion acoustic waves (IAWs) including the effects of dust charge fluctuation and electron nonextensivity is derived. It is shown that the presence of nonextensive electrons modifies the charge fluctuation behavior, leading to the dissipative and instability for IAWs. The dependence of the frequency and damping rate of IAWs on the electron nonextensive parameter q is closely to the dust density since it greatly affects the dust charge fluctuation.

On the nonlinear solitary and shock waves in Maxwellian multicomponent space plasma

Our objective is to study the nonlinear wave phenomena in a multicomponent plasma with Maxwellian electrons and ions. The main reason for this consideration is to exhibit the effects of dust charge fluctuations in plasma acoustic modes. Different aspects of nonlinear dynamics have been studied through the Korteweg-deVries (K-dV) equation (solitons) and the Burgers equation (shocks) derived by the reductive perturbation technique. A special method, known as the (G′/G) method, has been used for a solution. It predicts the different coherent features of various nonlinear waves successfully, and finally, their importance has been recognized in space plasmas. Evolutions have been shown with the input of appropriate typical plasma parameters to support our observations in space plasmas. All conclusions are in good agreement with the actual occurrences and could be of interest in furthering investigations in experiments and satellite observations in spaces. An important aspect of this exercise is a comparative study of K-dV and Burgers solutions in different plasma spaces.

Theoretical Modeling of an Ion-Beam-Driven Kelvin–Helmholtz Instability in a Plasma Cylinder Having Negatively Charged Dust Grains

An ion beam propagating through a magnetized plasma cylinder having negatively charged dust grains drives the Kelvin–Helmholtz instability (KHI) via Cerenkov interaction. The frequency and the growth rate of the KHI increase with the relative density of negatively charged dust grains $\delta $ . However, for large relative density of dust grains $\delta $ , the growth rate of KHI saturates. Moreover, beam density plays an important role in enhancing the growth rate of the KHI. It is also observed that finite boundary effects modify the dispersion properties of the KHI. The growth rate of KHI in a plasma cylinder is destabilized under the effect of dust charge fluctuations for relatively large velocity shears and low density of negatively charged dust grains $\delta $ . A comparative study of results is done for finite and infinite geometries of plasma waveguide.

New method for rekindling the nonlinear solitary waves in Maxwellian complex space plasma

Our interest is to study the nonlinear wave phenomena in complex plasma constituents with Maxwellian electrons and ions. The main reason for this consideration is to exhibit the effects of dust charge fluctuations on acoustic modes evaluated by the use of a new method. A special method (G′/G) has been developed to yield the coherent features of nonlinear waves augmented through the derivation of a Korteweg-de Vries equation and found successfully the different nature of solitons recognized in space plasmas. Evolutions have shown with the input of appropriate typical plasma parameters to support our theoretical observations in space plasmas. All conclusions are in good accordance with the actual occurrences and could be of interest to further the investigations in experiments and satellite observations in space. In this paper, we present not only the model that exhibited nonlinear solitary wave propagation but also a new mathematical method to the execution.

Dust-charge fluctuation effects on surface dust-acoustic waves in astrophysical half-space dusty plasmas

We investigate the dust-charge fluctuation effects on the propagation and the decay of the dust-acoustic surface plasma wave at the interface of plasma-vacuum in astrophysical half-space dusty plasmas. The dispersion relation for the surface mode is derived by using the appropriate plasma dielectric function. We found that wave frequency decreases as the dust-charging frequency increases as well as the dynamical wave number does. However, the damping rate of the surface wave increases with an increase of the dust-charging frequency and the dynamical wave number. Hence, the amplitude of the surface wave is found to be strongly suppressed with an increase of the dust-charging frequency. The increase of charging relaxation rate is found to suppress both of the real frequency of the wave and the damping rate of the surface wave in astrophysical half-space dusty plasmas.

Dust Ion-Acoustic Shock Waves in a Multicomponent Magnetorotating Plasma

Abstract The nonlinear properties of dust ion-acoustic (DIA) shock waves in a magnetorotating plasma consisting of inertial ions, nonextensive electrons and positrons, and immobile negatively charged dust are examined. The effects of dust charge fluctuations are not included in the present investigation, but the ion kinematic viscosity (collisions) is a source of dissipation, leading to the formation of stable shock structures. The Zakharov–Kuznetsov–Burgers (ZKB) equation is derived using the reductive perturbation technique, and from its solution the effects of different physical parameters, i.e. nonextensivity of electrons and positrons, kinematic viscosity, rotational frequency, and positron and dust concentrations, on the characteristics of shock waves are examined. It is observed that physical parameters play a very crucial role in the formation of DIA shocks. This study could be useful in understanding the electrostatic excitations in dusty plasmas in space (e.g. interstellar medium).

Dust charge fluctuation effects on Langmuir waves with kappa distributed electrons

Using a kinetic description, dust charge fluctuations due to the inelastic collisions between dust particles and plasma particles are studied in unmagnetized dusty plasmas. Most astrophysical and space plasmas are observed to have non-Maxwellian high energy tail. Therefore, a kappa distribution for electrons in the equilibrium is assumed. The dispersion relation and damping rates for Langmuir waves are obtained. Considering the dust charge fluctuations increases the damping rate of Langmuir waves. It is shown that the damping rate of Langmuir waves depends on the spectral index and the dust density parameter.

Effect of dust charge fluctuations on dust acoustic structures in magnetized dusty plasma containing nonextensive electrons and two-temperature isothermal ions

Effect of dust electrical charge fluctuations on the nature of dust acoustic solitary waves (DASWs) in a four-species magnetized dusty plasma containing nonextensive electrons and two-temperature isothermal ions has been investigated. In this model, the negative dust electric charge is considered to be proportional to the plasma space potential. The nonlinear Zakharov–Kuznetsov (ZK) and modified Zakharov–Kuznetsov (mZK) equations are derived for DASWs by using the standard reductive perturbation method. The combined effects of electron nonextensivity and dust charge fluctuations on the DASW profile are analyzed. The different ranges of the nonextensive q-parameter are considered. The results show that solitary waves the amplitude and width of which depend sensitively on the nonextensive q-parameter can exist. Due to the electron nonextensivity and dust charge fluctuation rate, our dusty plasma model can admit both positive and negative potential solitons. The results show that the amplitude of the soliton increases with increasing electron nonextensivity, but its width decreases. Increasing the electrical charge fluctuations leads to a decrease in both the amplitude and width of DASWs.

Effect of Dust Charge Fluctuation on Dust Acoustic Structures in Magnetized Dusty Plasma Containing Nonextensive Electrons and Two Temperatures Isothermal Ions

Effect of Dust Charge Fluctuation on Dust Acoustic Structures in Magnetized Dusty Plasma Containing Nonextensive Electrons and Two Temperatures Isothermal Ions

Effect of dust charge fluctuation on multidimensional instability of dust-acoustic solitary waves in a magnetized dusty plasma with nonthermal ions

Simultaneous effects of dust charge fluctuation and nonthermal ions on the threshold point and growth rate of three-dimensional instability of dust-acoustic solitary waves (DASW) in magnetized dusty plasma have been investigated. In this model, dusty plasma consists of Maxwellian electrons, nonthermal ions, and micron size negatively charged dust particles. Modified Zakharov-Kuznetsov equation for DASW was derived employing a reductive perturbation method and its solitary answer under the influence of dust charge fluctuation and nonthermal ions has been studied. The dispersion relation of DASW has been derived using a small-k perturbation method. Results show that the direction and the magnitude of external magnetic field at which the instability takes place are strongly affected by the rate of dust charge fluctuation and nonthermality of ions. With increasing the number of nonthermal ions, the growth rate of instability decreases, while increasing the dust charge fluctuation increases the growth rate of instability.

Shock Structures in Charge Variable Dusty Plasmas with Effect of Strongly Coupled Dust Particles

A theoretical investigation has been carried out to study the effect of strong electrostatic interaction on the dust acoustic shock structures in strongly coupled dusty plasma with dust charge fluctuations. The fluid approach is employed, in which the strong electrostatic interaction is modeled by effective electrostatic temperature. A Burger-like equation, the coefficients of which are significantly modified by effects of strong coupling and dust charge fluctuation, is derived. It is shown that the combined effects of dust charge fluctuation, the ion/electron temperature, the ion/electron population, and strong coupling effect modify the basic properties of the dust acoustic waves in such a strongly coupled dusty plasma. The results of this work are compared with those observed by some laboratory experiments.

Effect of dust-charge fluctuations on dust acoustic solitary waves in an inhomogeneous dusty plasma with nonextensive electrons

The effects of adiabatic dust grain charge fluctuation and inhomogeneity on the nonlinear properties of dust acoustic (DA) solitary waves are studied. The plasma under consideration is a hot magnetized dusty plasma consisting of negatively charged dust particles, Boltzmann ions, and nonextensive electrons. A modified Zakharov-Kusnetsov equation, which admits a solitary wave solution, is derived using the reductive perturbation theory. It is found that the charge fluctuation of the dust grain modifies the nature of DA solitary structures. The numerical results may be useful to understand phenomena in laboratory and astrophysical plasmas.

Effect of dust charge fluctuations on upper hybrid wave instabilities in magnetized dusty plasma

The decay instability of an upper hybrid electrostatic wave into an upper hybrid sideband wave and lower hybrid wave is studied in magnetized dusty plasma. A local theory of this process has been developed. The growth rate and mode frequencies of the unstable wave were evaluated based on existing dusty plasma parameters and it is found that the unstable mode frequency and growth rate increases with δ (ion-to-electron density ratio) in the presence and absence of dust charge fluctuations in addition to dust dynamics.

Effect of dust charge fluctuations on current-driven electrostatic ion-cyclotron instability in a collisional magnetized plasma

Current-driven electrostatic ion-cyclotron (EIC) instability is studied in a collisional magnetized dusty plasma. The growth rate and unstable mode frequencies were evaluated based on existing physical parameters relevant to ion cyclotron waves in dusty plasmas. It is found that the unstable mode frequency and growth rate of current-driven EIC instability increase with δ (ion-to-electron density ratio). Moreover, the increase in electron neutral collisional frequency (νe) has no effect on the unstable mode frequency while the normalized growth rate has linear dependence on νe.

Bohm criterion in a dusty plasma with nonextensive electrons and cold ions

The Bohm criterion in a dusty plasma containing nonextensively distributed electrons and cold ions is investigated within the framework of probe model including the effects of dust charge fluctuation. It is shown that the critical Mach number upshifts with the decrease of electron nonextensive parameter (qe) and the increase of the ion-to-electron number density ratio (Rn) when the effects of dust charge fluctuation are out of consideration. Once the effects of dust charge fluctuation are included, with the increase of Rn, the critical Mach number increases first, then decreases. The slop of the critical Mach number curves in the region Rn≫1 for qe>1 becomes more gradual than that for qe<1. When critical Mach number is defined with respect to modified ion acoustic wave speed, it should be larger than unity in the case free of dust charge fluctuation. Whereas when Rn≫1, it may be smaller than unity due to the effect of dust charge fluctuation.