Effect Of Polarization Force Research Articles

Nonlinear dust acoustic waves with polarization force effects in Kappa distribution plasma

The propagation characteristics of dust acoustic solitary waves (DASWs) in dusty plasmas with the effects of polarization force and superthermal ions are studied. First, the polarization force induced by superthermal ions is obtained. It is shown that the superthermality of background ions affect the Debye screening of dust grains as well as the polarization force significantly. Then for small amplitude solitary waves, the KdV equation is obtained by applying the reductive perturbation technique. And for the arbitrary amplitude solitary waves, the Sagdeev potential method is employed and the Sagdeev potential is analyzed. In both case, the effects of the polarization force associated the ions’ superthermality on the characteristic of the DASWs are analyzed.

Child–Langmuir law applicability for a cathode sheath description of glow discharge in hydrogen

The present paper reveals that the Child-Langmuir law version with the constant ion mobility has to be applied for the cathode sheath description of the glow discharge in hydrogen. Using the analytical model we demonstrate that even in a high electric field the constant mobility law version rather than that for the constant ion mean free path has to hold in the case of impeded charge exchange and the dominant effect of polarization forces on the ion motion through the cathode sheath.

Nonlinear ion modes in a strongly coupled plasma in the presence of nonthermal ion fluids and polarization force

The nonlinear propagation of ion-acoustic (IA) waves in a strongly coupled plasma system containing Maxwellian electrons and nonthermal ions has been theoretically and numerically investigated. The well-known reductive perturbation technique is used to derive both the Burgers and Korteweg−de Vries (KdV) equations. Their shock and solitary wave solutions have also been numerically analyzed in understanding localized electrostatic disturbances. It has been observed that the basic features (viz. polarity, amplitude, width, etc.) of IA waves are significantly modified by the effect of polarization force and other plasma parameters (e.g., the electron-to-ion number density ratio and ion-to-electron temperature ratio). This is a unique finding among all theoretical investigations made before, whose probable implications are discussed in this investigation. The implications of the results obtained from this investigation may be useful in understanding the wave propagation in both space and laboratory plasmas.

Effect of polarization force on low-frequency dust modes with quantum correction

In the present work, the effect of dust polarization force on different low-frequency dust modes is investigated in ultra-cold quantum dusty plasma. The quantum hydrodynamic model has been employed for electron, ion and charged dust species and the analysis has been done using the normal mode technique. It is observed that the dispersion relation of low-frequency dust modes significantly modified due to the inclusion of polarization force, neutral particles and quantum correction. The numerical analysis has also been presented to see the effect of dust polarization force on dispersion properties of different low-frequency modes. The phase speed of each mode is found to be modified due to the polarization force.

Radiative condensation instability in partially ionized dusty plasma with polarization force

This paper studies the effect of polarization force on the radiative condensation (RC) instability of a partially ionized dusty medium both in the presence and absence of self-gravitation. The temperature and density dependent heat loss function is considered in the process of heating and radiative cooling. The linear-perturbation analysis is used to derive general dispersion relation and criteria for both the Jeans and RC instability. The condition of Jeans instability is modified due to the RC, polarization force, magnetic field and dust thermal speed, whereas in the case of RC instability the instability criterion is modified due to the presence of dust thermal speed, magnetic field and polarization force. The effects of various parameters have been numerically estimated on RC instability. It is clear from figure that the presence of polarization parameter and density dependent heat-loss function destabilize the system while the presence of temperature dependent heat-loss function, dust neutral collision frequency and ratio of neutral dust density stabilize the system. These findings are relevant for many areas of space and laboratory plasma research prime examples being the formation of dense molecular clouds in interstellar and intergalactic medium, condensations in planetary nebulae and in laboratory plasmas like tokamak edge plasma.

Influence of dust charge fluctuation and polarization force on radiative condensation instability of magnetized gravitating dusty plasma

The influence of dust charge fluctuation, thermal speed and polarization force due to massive charged dust grains is studied on the radiative condensation instability (RCI) of magnetized self-gravitating astrophysical dusty (complex) plasma. The dynamics of the charged dust and inertialess electrons are considered while the Boltzmann distributed ions are assumed to be thermal. The dusty fluid model is formulated and the general dispersion relations are derived analytically using the plane wave solutions under the long wavelength limits in both the presence and the absence of dust charge fluctuations. The combined effects of polarization force, dust thermal speed, dust charge fluctuation and dust cyclotron frequency are observed on the low frequency wave modes and radiative modified Jeans Instability. The classical criterion of RCI is also derived which remains unaffected due to the presence of these parameters. Numerical calculations have been performed to calculate the growth rate of the system and plotted graphically. We find that dust charge fluctuation, radiative cooling and polarization force have destabilizing while dust thermal speed and dust cyclotron frequency have stabilizing influence on the growth rate of Jeans instability. The results have been applied to understand the radiative cooling process in dusty molecular cloud when both the dust charging and polarization force are dominant.

Head-on collision of dust-acoustic shock waves in strongly coupled dusty plasmas

A theoretical investigation is carried out to study the propagation and the head-on collision of dust-acoustic (DA) shock waves in a strongly coupled dusty plasma consisting of negative dust fluid, Maxwellian distributed electrons and ions. Applying the extended Poincaré–Lighthill–Kuo method, a couple of Korteweg–deVries–Burgers equations for describing DA shock waves are derived. This study is a first attempt to deduce the analytical phase shifts of DA shock waves after collision. The impacts of physical parameters such as the kinematic viscosity, the unperturbed electron-to-dust density ratio, parameter determining the effect of polarization force, the ion-to-electron temperature ratio, and the effective dust temperature-to-ion temperature ratio on the structure and the collision of DA shock waves are examined. In addition, the results reveal the increase of the strength and the steepness of DA shock waves as the above mentioned parameters increase, which in turn leads to the increase of the phase shifts of DA shock waves after collision. The present model may be useful to describe the structure and the collision of DA shock waves in space and laboratory dusty plasmas.

Effects of polarization force and nonthermal ions on dust-acoustic (DA) shock waves in a strongly coupled dusty plasma with positively charged dust

Abstract The nonlinear propagation of the dust-acoustic (DA) waves in a strongly coupled dusty plasma containing Maxwellian electrons, nonthermal ions, and positively charged dust is theoritically investigated by a Burgers equation. The effects of the polarization force (which arises due to the interaction between electrons and highly positively charged dust grains) and nonthermal ions are studied. DA shock waves are found to exist with positive potential only. It represents that the strong correlation among the charged dust grains is a source of dissipation, and is responsible for the formation of DA shock waves. The effects of polarization force and nonthermal ions significantly modified the basic features of DA shock waves in strongly coupled dusty plasma.

Effect of polarization force on the Mach cones in a complex plasma

We report the modifications of compressional Mach cone propagation characteristics due to the polarization force acting on micron size dust particles embedded in a non-uniform plasma. We solve the hydrodynamic fluid equations for highly charged dust particles to investigate the Mach cone by incorporating the polarization force in the momentum equation and observe the structural change on lateral wakes at different polarization force for a given Mach number and Epstein drag force. We also notice that the maximum amplitude of normalized dust density perturbation decreases with the increase of polarization interaction when the other parameters remain constant.

Dust-acoustic waves in a nonuniform adiabatic dusty plasma in the presence of polarization force

The linear propagation of the dust-acoustic (DA) waves in a nonuniform adiabatic dusty plasma, which consists of inertialess adiabatic electrons, inertialess adiabatic ions, and inertial negatively charged dust by taking into account the effects of polarization force, is theoretically investigated. It is found that the linear dispersion properties of the DA waves are significantly modified by the dust density nonuniformity, adiabaticity of electrons and ions, and the effects of the polarization force. It is shown that the phase speed of the DA waves is increased with the increase of adiabaticity of electrons and ions but decreased with the increase of the effects of polarization force. It is also shown that the dust density is enhanced with the increase of adiabatic index but depleted with the increase of polarization force. The scenarios relevant to dust-ion plasma in space environments are briefly addressed.

Effects of polarization force and fast electrons on DA shock waves in a strongly coupled dusty plasma

AbstractA strongly coupled dusty plasma system consisting of non-thermal electrons, Maxwellian ions, and negatively charged dust in presence of polarization force has been considered. The nonlinear propagation of dust-acoustic shock waves in such a dusty plasma system has been theoretically investigated by employing the reductive perturbation method. The effects of the polarization force and non-thermal electrons, on the properties of these dust-acoustic shock waves are briefly discussed. It is shown that the strong correlation among the charged dust grains is a source of dissipation, and is responsible for the formation of the dust-acoustic shock waves. It has been found that the effects of polarization force and non-thermal electrons significantly modify the basic features of such shock waves. It has been proposed to design a new laboratory experiment, which will be able to identify the basic features of the dust-acoustic shock waves predicted in this present investigation.

Dust-acoustic waves in nonuniform dusty plasma in presence of polarization force

The effects of the dust density nonuniformity and the polarization force on linear propagation of the dust-acoustic waves in a nonuniform dusty plasma (consisting of electrons, ions, and arbitrarily charged dust particles) have been theoretically investigated. It has been shown that the linear dispersion properties of the dust-acoustic (DA) waves have been significantly modified by the dust density nonuniformity, dust polarity, and the polarization force. It is also found here that the phase speed of the DA waves is decreased by the effects of polarization force, and that their amplitude increases with the decrease of equilibrium dust number density. The different situations, which are relevant to different space and laboratory dusty plasmas, have been briefly discussed.

Dust-acoustic solitary waves in a strongly coupled inhomogeneous dusty plasma in the presence of polarization force and effective dust-temperature

The nonlinear propagation of the dust-acoustic waves is studied in a strongly coupled inhomogeneous dusty plasma which consists of the strongly correlated negatively charged dust grains and weakly correlated electrons and ions. The Korteweg-de Vries equation with variable coefficients and an additional term due to the density gradient is deduced, and its solution is found by appropriate transformations. The propagation of two possible modes (fast and slow) and their evolution are investigated. Only the fast rarefactive solitary waves are found to propagate in such plasma with parameter ranges corresponding to the experimental conditions. It is shown that the special patterns of nonlinear DA waves (e.g., amplitude and width) are significantly modified in a way that depends upon the effects of polarization force (which arises due to the interaction between thermal ions and highly negatively charged dust grains), effective dust-temperature (which arises from the electrostatic interactions among highly negatively charged dust and from the dust thermal pressure), equilibrium electron density, and ion temperature. The amplitude of solitary waves also decreases as the wave propagates in the direction of increasing dust concentration.

Effect of polarization force on the Jeans instability of self-gravitating dusty plasma

The effect of polarization force acting on massive charged dust grains is investigated analytically on the Jeans instability of self-gravitating dusty plasma. The gravitational force acting on the massive negatively charged interstellar dust grains are considered in presence of both electrical and polarization forces. The basic equations of the problem are formulated and a general dispersion relation is obtained using plane wave approximation in low frequency wave mode. The effect of polarization force in the dispersion relation of the problem, condition of the Jeans instability and expression of the critical Jeans wave number is examined. The unstable growing modes due to self-gravitational force are studied in the situation when polarization force on the dust grain exceeds over the electrical force in magnitude. It is observed that the polarization force increases the growth rate of the system.

Effects of polarization force and effective dust temperature on dust-acoustic solitary and shock waves in a strongly coupled dusty plasma

A strongly coupled dusty plasma containing strongly correlated negatively charged dust grains and weakly correlated (Maxwellian) electrons and ions has been considered. The effects of polarization force (which arises due to the interaction between thermal ions and highly negatively charged dust grains) and effective dust temperature (which arises from the electrostatic interactions among highly negatively charged dust and from the dust thermal pressure) on the dust-acoustic (DA) solitary and shock waves propagating in such a strongly coupled dusty plasma are taken into account. The DA solitary and shock waves are found to exist with negative potential only. It has been shown that the strong correlation among the charged dust grains is a source of dissipation and is responsible for the formation of the DA shock waves. It has also been shown that the effects of polarization force and effective dust-temperature significantly modify the basic features (e.g., amplitude, width, and speed) of the DA solitary and shock waves. It has been suggested that a laboratory experiment be performed to test the theory presented in this work.

Effect of polarization force on the propagation of dust acoustic solitary waves

We report the modifications in the propagation characteristics of dust acoustic solitary waves (DASWs) due to the polarization force acting on micron-size dust particles in a non-uniform plasma. In the small amplitude limit, we derive a K–dV-type equation and show that there is an increase in the amplitude and a reduction in the width of a solitary structure as the polarization force is enhanced for a given Mach number. For arbitrary amplitude waves we employ the Sagdeev potential method and find that the range of Mach numbers where solitary structures can exist becomes narrower in the presence of the polarization interaction. In both limits there exists a critical value of grain size beyond which the DASW cannot propagate.

Macroscopic electromagnetic stress tensor for ionized media

AbstractFollowing the arguments presented by Mansuripur [Opt. Express, vol.16, 2008, pp. 14821–14835], we suggest a form for the macroscopic electromagnetic stress tensor appropriate for ionized media. The generalized Lorentz force includes the effects of polarization forces as well as those on the free charge and current densities. The resulting tensor is written in terms of the fieldsD,B,E, andH. Its expression for a fully ionized medium subject to an external electromagnetic field is discussed, as are the plasma conservation equations. An apparatus is suggested for its experimental discrimination.

Effects of polarization forces between excited atomic states and point charges on the ionization equilibrium in plasmas

A generalized Saha equation which explicitly includes excited atomic states and their interactions is used for calculating the degree of ionization and the effective ionization potential for a dense classical partially ionized hydrogen plasma. The effective ionization potential for each atomic state, characterized by the principal quantum number n, is calculated as is the change ..delta..I/sub n/ of the ionization potential due to different types of particle interactions, i.e., atom-atom, atom-ion, atom-electron, and ion-electron interactions. The effective ionization potential for each state is used for determining n*, the maximum admissible principal quantum number for a hydrogen atom in a plasma. It is found that the strongest influence on the effective ionization potential comes from the familiar electron-ion interactions (Debye shielding), and from the less effective but not negligible induced-dipole interactions between atom-ion and atom-electron pairs. The van der Waals interactions of the dispersion-type turn out to be negligible in agreement with earlier work. The changes ..delta..I/sub n/ are shown to produce corresponding changes in the population of the atomic states which are of the order of ten percent; however, the degree of ionization of the total atom is found to be very insensitive to the ..delta..I/sub n/, and to varymore » only one tenth of a percent by order of magnitude.« less

Addendum to "Lumped parameter electromechanics of electret transducers"

An error in a Maxwell stress tensor integral of the previous publication is identified, and two new volume and surface integration methods are presented as a check on the original lumped parameter electromechanical formulation. The two new methods verify the original result and clarify the issue of the effect of polarization forces on the electret.