Interaction of Langmuir solitary waves with electrons of a plama

Interaction of Langmuir solitary waves with superthermal electrons of a plasma is considered. The number of solitary waves per unit length N is assumed to be small, therefore interaction of solitary waves with each other may be neglected. The initial phase of the process of relaxation of the electron distribution function is considered numerically. Continuous generation of accelerated elctrons up to velocities larger than thermal electron velocities is obtained.     

Dust-acoustic solitary waves in an adiabatic hot dusty plasma

An adiabatic hot dusty plasma (containing non-inertial adiabatic electron and ion fluids, and negatively charged inertial adiabatic dust fluid) is considered. The basic properties of arbitrary amplitude dust-acoustic (DA) solitary waves, which exist in such an adiabatic hot dusty plasma, are explicitly examined by the pseudo-potential approach. To compare the basic properties (critical Mach number, amplitude and width) of the DA solitary waves observed in a dusty plasma containing adiabatic electron, ion and dust fluids with those observed in a dusty plasma containing isothermal electron and ion fluids and adiabatic dust fluid, it has been found that the adiabatic effect of inertia-less electron and ion fluids has significantly modified the basic properties of the DA solitary waves, and that on the basic properties of the DA solitary waves, the adiabatic effect of electron and ion fluids is much more significant than that of the dust fluid.     

Formation of solitary structures and envelope solitons in electron acoustic wave in inner magnetosphere plasma with suprathermal ions

The propagation of electron acoustic solitary waves is investigated in magnetized two-temperature electron plasma with supra-thermal ion. By using the reductive perturbation technique, the Korteweg de-Vries (KdV) equation is derived. Later solving this equation, a solitary wave solution has been derived. These are mainly in astrophysical plasmas where changes of local charge density, temperature, and energy of particles produce considerable effects on the plasma system. The effects of supra-thermality, density, and Mach number on solitary structures are studied in detail. The results show that the supra-thermal index (κ) and ion to electron temperature ratio (σ) alters the regime where solitary waves may exist. While studying the solitary profile for different parametric variation some interesting conclusion can be drawn; it is shown that the solitary profile becomes flatter. This can be due to the thermal energy associated with the hot electrons. However, with the increase in ion density with respect to the cold electrons' density, the solitary waves become steeper and sharper. This is due to the comparatively heavier mass of ions. The density of cold electron also increases the solitary structures in a similar manner. The higher the density of cold electrons, sharper will be the profile. The above findings will be helpful in understanding many astrophysical phenomena and data obtained by space missions. For a further study, we keep the investigation of the formation of other kinds of stationary structures like shocks, double layers, etc.     

Effect of excavated trapped electron distributions on ion-acoustic solitary structures in an electron-positron-ion plasma

Fully nonlinear propagation of ion-acoustic solitary waves in an unmagnetized electron-positron-ion plasma is investigated. A more realistic situation is considered in which electrons interact with the wave potential during its evolution and, follow the vortex-like excavated trapped distribution. The basic properties of large amplitude solitary waves are studied by deriving an energy integral equation involving Sagdeev potential. It is shown that effects of such electron behavior and positron concentration change the maximum values of the Mach number and amplitude for which solitary waves can exist. The small amplitude limit is also investigated by expanding the Sagdeev potential to include third-order nonlinearity of electric potential. In this case, exact analytical solution is obtained which is related to the contribution of the resonant electron to the electron density. It is shown from both highly and weakly nonlinear analysis that the plasma system under consideration supports only compressive solitary waves.     

Head-on collision of ion acoustic solitary waves in electron-positron-ion plasma with superthermal electrons and positrons

The head-on collision of ion acoustic solitary waves are studied in an electron-positron-ion plasma composed of superthermal electrons, superthermal positrons, and cold ions using the extended Poincaré-Lighthill-Kuo (PLK) method. The effects of the ratio of electron to positron temperature, the spectral index of electron and positron, and the concentration of positron component on the phase shift are studied. It is found that the presence of superthermal electrons and superthermal positrons play a significant role on the collision of ion acoustic solitary waves. It is also been observed that the temperature ratio plays a significant role on the collision of ion acoustic solitary waves.     

Optical characterization of weakly absorbing PP,PE, and PP/PE films

The interaction between a solitary electromagnetic wave and a narrow layer with an increased electron concentration in a semiconductor superlattice in a preset uniform alternating electric field directed along the superlattice axis is investigated. The model of the electron energy spectrum in the superlattice is chosen in the strong coupling approximation taking into account the second harmonic. It is shown that, for certain relations between the amplitude and frequency of the alternating electric field, a solitary electromagnetic wave approaching the layer with an increased electron concentration can be trapped by this layer.     

Spiky whistler solitons

Purely ponderomotive force-driven electron motion is shown to produce spiky electron whistler solitary waves.     

Solitary wave propagation in quantum electron-positron plasmas

Existence of large amplitude stationary solitary wave structures in an unmagnetized electron-positron (e-p) plasma is studied using a quantum hydrodynamic (QHD) model that includes the quantum force (tunnelling) associated with the Bohm potential and the Fermi-dirac pressure law. It is found that in a quasi-neutral pair (e-p) plasma, where the dispersion is only due to the the quantum tunnelling effects, the large amplitude stationary solitary structure exists only when the normalized Mach speed,M <√2. Such solitary structures do not exist in absence of the Bohm potential term in an unmagnetized quasineutral pair (e-p) plasma. The system is shown to support only rarefactive stationary solitary waves. For such waves the amplitude, being independent of the quantum parameter H (the ratio of the electron plasmon to electron Fermi energy), decreases with the Mach number M, whereas the width increases with both M and H. The present theory is applicable to analyze the formation of localized coherent solitary structures at quantum scales in dense astrophysical objects as well as in intense laser fields.     

Solitary waves and rogue waves in a plasma with nonthermal electrons featuring Tsallis distribution

In this Letter, we discuss the electron acoustic (EA) waves in plasmas, which consist of nonthermal hot electrons featuring the Tsallis distribution, and obtain the corresponding governing equation, that is, a nonlinear Schrödinger (NLS) equation. By means of Modulation Instability (MI) analysis of the EA waves, it is found that both electron acoustic solitary wave and rogue wave can exist in such plasmas. Basing on the Darboux transformation method, we derive the analytical expressions of nonlinear solutions of NLS equations, such as single/double solitary wave solutions and single/double rogue wave solutions. The existential regions and amplitude of solitary wave solutions and the rogue wave solutions are influenced by the nonextensive parameter q and nonthermal parameter α. Moreover, the interaction of solitary wave and how to postpone the excitation of rogue wave are also studied.     

Nonlinear interaction phenomenon of dust acoustic solitary and shock waves in dusty plasma

The effects of head-on collision on dust acoustic (DA) solitary and shock waves in dusty plasma are investigated considering positively charged inertial dust, Boltzmann distributed negatively charged heavy ions, positively charged light ions, and superthermal electrons in the plasma system. The nonlinear Korteweg-de-Vries (KdV) Burger equations are derived taking the extended Poincaré-Lighthill-Kuo method into account to study the characteristic properties of nonlinearity and production of solitary shock due to collisions. The study reveals that the amplitudes and widths of the DA shock waves are decreasing with increasing viscosity, electron to dust density ratio, and dust to ion temperature ratio, while they are increasing due to the presence of superthermal electrons. The nonlinearity of DA waves are enhanced with increasing density ratio of electron to dust and temperature ratio of dust to ion and electron, respectively, but it is reducing with superthermal electrons. The phase shifts of DA solitary waves are found to decrease with rising superthermality of electrons and increase with the density ratio of electron to dust.     

Plasma response to transient high voltage pulses

This review reports on plasma response to transient high voltage pulses in a low pressure unmagnetized plasma. Mainly, the experiments are reviewed, when a disc electrode (metallic and dielectric) is biased pulsed negative or positive. The main aim is to review the electron loss in plasmas and particle balance during the negative pulse electrode biasing, when the applied pulse width is less than the ion plasma period. Though the applied pulse width is less than the ion plasma period, ion rarefaction waves are excited. The solitary electron holes are reviewed for positive pulsed bias to the electrode. Also the excitation of waves (solitary electron and ion holes) is reviewed for a metallic electrode covered by a dielectric material. The wave excitation during and after the pulse withdrawal, excitation and propagation characteristics of various electrostatic plasma waves are reviewed here.     

Solitary ion-acoustic wave propagation in the presence of electron trapping and background nonextensivity

Solitary ion-acoustic wave propagation in the presence of electron trapping is investigated within the theoretical framework of the Tsallis statistical mechanics. A physically meaningful Schamel-like distribution is outlined. In the small amplitude limit, the nonlinear dispersion relation is derived to analyze the global dependency of the main solitary wave quantities. It is found that for a given amplitude and trapping state, the solitary potential structure speeds up and broadens as the electron nonextensivity strengthens. Our results may be of basic interest for experiments that involve particle trapping. The flexibility provided by the nonextensive q-parameter enables one to obtain a good agreement between theory and experiment.     

Effect of the field of a nonlinear electromagnetic wave on the shape of a soliton in a semiconductor superlattice

The effect of the electric component of the field of a high-frequency (HF) nonlinear electromagnetic (EM) wave on the propagation of a solitary EM wave (soliton) in a quantum semiconductor superlattice is studied. It is noted that in the collisionless approximation, the solution of the modified sine-Gordon equation corresponding to the amplification of an EM pulse that, with allowance made for interminiband electron transitions, transforms into a dissipative soliton is possible. The effect of electron collisions with irregularities of the crystal lattice on the soliton dynamics under the action of the field of a HF nonlinear wave is considered. The condition for an increase in the traveling time of the solitary wave is found.     

激光偏振状态对磁化等离子体中电磁孤波的影响

强激光与等离子体之间相互作用,能够产生各种参量不稳定性过程和非线性效应。利用Karpman方法推导出横场包络所满足的非线性控制性方程,在一维情况下,获得孤波解。对孤波解进行分析,发现波包孤子的半宽反比于振幅;分析磁化等离子体中各参量对孤波半宽的影响。结果表明,在右旋圆偏振激光情况下,随着电子数密度的增大,孤波的半宽逐渐减小,而当磁场强度增大时,孤波的半宽逐渐增大;在左旋圆偏振激光情况下,随着电子数密度的增大,孤波的半宽逐渐增大,而当磁场强度增大时,孤波的半宽逐渐减小。     

Effect of electron inertia on large amplitude solitary waves in presence of kinematic viscosity in dusty plasma

Nonlinear dust acoustic solitary waves in a dusty plasma are studied for nonzero kinematic viscosity. Sagdeev’s potential can be obtain upto any order in ϕ. The existence of soliton solution is determined by pseudopotential approach. It is seen that the electron inertia has a significant effect on the existence of solitary waves in presence of kinematic viscosity.     

Nonplanar Electrostatic Solitary Waves in a Relativistic Degenerate Dense Plasma

By employing the reductive perturbation technique, the propagation of cylindrical and spherical ion acoustic solitary waves is studied in an unmagnetized dense relativistic plasma, consisting of relativistically degenerate electrons and cold fluid ions. A modified Korteweg-de-Vries equation is derived and its numerical solutions have been analyzed to identify the basic features of electrostatic solitary structures that may form in such a degenerate Fermi plasma. Different degrees of relativistic electron degeneracy are discussed and compared. It is found that increasing number density leads to decrease the amplitude the width of the ion acoustic solitary wave in both the cylindrical and spherical geometries. The relevance of the work to the compact astrophysical objects, particularly white dwarfs is pointed out.     

Effect of deviations from isothermality of ions on the propagation of localized dust-acoustic waves

The effect of deviations from isothermality of ions on arbitrary amplitude dust-acoustic solitary structures is studied in an unmagnetized dusty plasma which consists of a negative charged dust fluid, free electrons and hot ions obeying a trapped distribution. For the finite deviation from isothermality of ions, the basic properties of large amplitude solitary waves are studied by employing pseudo-potential approach. It is shown that the effect of such ion behavior changes the maximum values of the Mach number and the amplitude for which solitary wave can exist. For the case that the deviation from isothermality due to nonlinear resonant particle effects is small, calculations by reductive perturbation method leads to a generalized Korteweg-de Vries equation with mixed nonlinearity. The latter admits a stationary dust-acoustic solitary solution with similar width and qualitatively different amplitude in comparison to the case that deviations from isothermality are finite. Furthermore, effects of the equilibrium free electron density and such trapped ions on the amplitude of solitary structures imply a non-uniform transition from the Boltzmann ion distribution to the trapped ion one.     

Non linear analysis of obliquely propagating spin electron acoustic wave in a partially spin polarized degenerate plasma

By employing the separated spin evolution quantum hydrodynamic model, non-linear evolution of obliquely propagating spin electron acoustic wave (SEAW) is presented. The solitary structures of SEAW is investigated through the Korteweg–de Vries (KdV) equation derived using reductive perturbation method. From the first order perturbations we derive the dispersion relation of SEAW and find that both the spin polarization and the propagation angle reduce the phase velocity while the electron streaming enhances it. Using small amplitude approximation, the solitary structure of SEAW is analyzed and the effects of spin polarization, propagation angle and electron streaming on the SEA soliton are studied. Our numerical results demonstrate that the spin polarization and the propagation angle play a balancing act on the soliton structures. The possible applications of our investigation to the astrophysical environments like white dwarfs is also discussed.     

Head-on collision of ion-acoustic solitary waves in an unmagnetized electron-positron-ion plasma

The head-on collision between two ion-acoustic solitary waves in an unmagnetized electron-positron-ion plasma has been investigated. By using the extended Poincaré-Lighthill-Kuo perturbation method, we obtain the KdV equation and the analytical phase shift after the head-on collision of two solitary waves in this three-component plasma. The effects of the ratio of electron temperature to positron temperature, and the ratio of the number density of positrons to that of electrons on the phase shift are studied. It is found that these parameters can significantly influence the phase shifts of the solitons. Moreover, the compressive solitary wave can propagate in this system.