Biswajit Sahu

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

The head-on collision of ion acoustic solitary waves in a three-component unmagnetized plasma with cold ions, Boltzmann distributed positrons, and superthermal electrons is investigated using the extended Poincare–Lighthill–Kuo method. The effects of the ratio of electron temperature to positron temperature, the spectral index, κ, of the electron kappa distribution, and fractional concentration of positron component (p) on the phase shift are studied. It is found that the presence of superthermal electrons play a significant role on the collision of ion acoustic solitary waves.

Electron acoustic solitary waves and double layers with superthermal hot electrons

The problem of arbitrary amplitude electron acoustic solitary waves (EASWs) are discussed using Sagdeev’s pseudopotential technique for a plasma comprising cold electrons, superthermal hot electrons, and stationary ions. The standard normal-mode analysis is used to study the dispersion relation for linear waves. It is found that the present plasma model supports EASWs having negative potential. The influence of superthermal hot electrons on the present plasma model is investigated for the existence of solitary waves. The investigation shows that the solitary structure ceases to exist when the parameter κ crosses a certain limit. It is also found that the small amplitude double layer solution can exist in such a plasma system in some parametric regions. It is shown that solitary structures and double layers are affected by superthermality, as well as by relevant plasma parameters.

Ion acoustic solitary waves and double layers with nonextensive electrons and thermal positrons

By using Sagdeev’s pseudopotential technique, the problem of arbitrary amplitude ion acoustic solitary waves (IASWs) is discussed for a plasma comprising nonextensive electrons and thermal positrons. The standard normal-mode analysis is used to study the dispersion relation for linear waves. It is found that the present plasma model supports IASWs having positive as well as negative potential well. The influence of nonextensive electrons on the present plasma model is investigated for the existence of solitary waves. The investigation shows that the solitary structure ceases to exist when the parameter q crosses a certain limit. It is also found that both the small amplitude compressive and rarefactive double layer solution can exist in such a plasma system in some parametric region. It is shown that solitary structures and double layers are affected by nonextensivity, as well as by relevant plasma parameters.

Positron acoustic shock waves in planar and nonplanar geometry

The nonlinear positron acoustic shock waves (PASWs) in an unmagnetized plasma consisting of cold positrons, immobile positive ions and Boltzmann-distributed electrons and hot positrons are studied in both unbounded planar geometry and bounded nonplanar geometry. In this regard, with the help of the reductive perturbation method, the cylindrical and spherical Korteweg–de Vries Burger (KdVB) equations are derived for PASWs. Numerically, the effects of several parameters and ion kinematic viscosities on the properties of PASWs in both planar and nonplanar geometry are discussed. It is found that PASWs in nonplanar geometry significantly differ from those in planar geometry.

Nonplanar electron acoustic shock waves in a plasma with electrons featuring Tsallis distribution

The properties of cylindrical and spherical electron acoustic shock waves (EASWs) in an unmagnetized plasma consisting of cold electrons, immobile ions, and hot electrons featuring Tsallis statistics are investigated by employing the reductive perturbation technique. A Korteweg-de Vries Burgers (KdVB) equation is derived and its numerical solution is obtained. The effects of electron nonextensivity and electron kinematic viscosity on the basic features of EA shock waves are discussed in nonplanar geometry. It is found that nonextensive nonplanar EA shock waves behave quite differently from their planar counterpart. Deviations from a pure planar geometry are significant only for times shorter that the inverse of the cold electron plasma frequency. Given that the hot electron dynamics is the most interesting one, and that in many astrophysical scenarios the cold electrons can be significantly rarefied, this restriction is not too limiting for the applicability of our model.

Propagation of two solitons in electron acoustic waves with superthermal electrons

A theoretical investigation is carried out for understanding the nonlinear properties of electron acoustic solitary waves (EASWs) in an unmagnetized, collisionless plasma consisting of a cold-electron fluid and hot electrons obeying κ velocity distribution, and stationary ions in nonplanar geometry. By making use of the reductive perturbation technique, nonlinear nonplanar (cylindrical/spherical) Korteweg-de Vries (KdV) equations are derived to study the propagation of two solitons. Computational investigations have been performed to examine the superthermal effects on the nonlinear waves. It is found that the propagation of two solitons is affected by superthermal hot electrons and other plasma parameters. Copyright c EPLA, 2013

Zakharov-Kuznetsov equation for ion acoustic waves with superthermal electrons in cylindrical geometry

The nonlinear wave structures of ion acoustic waves (IAWs) in a magnetized plasma with the combined effect of bounded cylindrical geometry and superthermal electrons and warm ions are studied. Using the standard reductive perturbation technique, the nonlinear cylindrical Zakharov-Kuznetsov (ZK) equation is derived for the propagation of ion acoustic solitary waves (IASWs). The influence of superthermal electrons and the effects caused by the cylindrical geometry on IAWs are investigated. It is shown that, in cylindrical geometry a new type of solitonlike structures appears as time goes by. It is also observed that a decrease in the superthermality of electrons (i.e., increasing ?) increases the amplitude of the solitary electrostatic potential structures. The numerical results are also presented to understand the formation of IASWs in relation with the plasma parameters in nonplanar geometry. The present investigation is of relevance in the study of propagation of IAWs in space and laboratory plasmas.

Nonplanar ion acoustic waves with kappa-distributed electrons

Using the standard reductive perturbation technique, nonlinear cylindrical and spherical Kadomtsev-Petviashvili equations are derived for the propagation of ion acoustic solitary waves in an unmagnetized collisionless plasma with kappa distributed electrons and warm ions. The influence of kappa-distributed electrons and the effects caused by the transverse perturbation on cylindrical and spherical ion acoustic waves (IAWs) are investigated. It is observed that increase in the kappa distributed electrons (i.e., decreasing κ) decreases the amplitude of the solitary electrostatic potential structures. The numerical results are presented to understand the formation of ion acoustic solitary waves with kappa-distributed electrons in nonplanar geometry. The present investigation may have relevance in the study of propagation of IAWs in space and laboratory plasmas.

Quasi-periodic behavior of ion acoustic solitary waves in electron-ion quantum plasma

The ion acoustic solitary waves are investigated in an unmagnetized electron-ion quantum plasmas. The one dimensional quantum hydrodynamic model is used to study small as well as arbitrary amplitude ion acoustic waves in quantum plasmas. It is shown that ion temperature plays a critical role in the dynamics of quantum electron ion plasma, especially for arbitrary amplitude nonlinear waves. In the small amplitude region Korteweg-de Vries equation describes the solitonic nature of the waves. However, for arbitrary amplitude waves, in the fully nonlinear regime, the system exhibits possible existence of quasi-periodic behavior for small values of ion temperature.

Multidimensional ion-acoustic solitary waves and shocks in quantum plasmas

The nonlinear theory of two-dimensional ion-acoustic (IA) solitary waves and shocks (SWS) is revisited in a dissipative quantum plasma. The effects of dispersion, caused by the charge separation of electrons and ions and the quantum force associated with the Bohm potential for degenerate electrons, as well as, the dissipation due to the ion kinematic viscosity are considered. Using the reductive perturbation technique, a Kadomtsev–Petviashvili–Burgers (KPB)-type equation, which governs the evolution of small-amplitude SWS in quantum plasmas, is derived, and its different solutions are obtained and analyzed. It is shown that the KPB equation can admit either compressive or rarefactive SWS according to when H≶2/3, or the particle number density satisfies n0≷1.3×1031cm−3, where H is the ratio of the electron plasmon energy to the Fermi energy densities. Furthermore, the properties of large-amplitude stationary shocks are studied numerically in the case when the wave dispersion due to charge separation is negligible. It is also shown that a transition from monotonic to oscillatory shocks occurs by the effects of the quantum parameter H.