M. M. Masud

Effects of bi-kappa distributed electrons on dust-ion-acoustic shock waves in dusty superthermal plasmas

The basic properties of dust-ion-acoustic (DIA) shock waves in an unmagnetized dusty plasma (containing inertial ions, kappa distributed electrons with two distinct temperatures, and negatively charged immobile dust grains) are investigated both numerically and analytically. The hydrodynamic equation for inertial ions has been used to derive the Burgers equation. The effects of superthermal bi-kappa electrons and ion kinematic viscosity, which are found to modify the basic features of DIA shock waves significantly, are briefly discussed.

Dust-acoustic Gardner solitons and double layers in dusty plasmas with nonthermally distributed ions of two distinct temperatures.

A rigorous theoretical investigation has been performed on dust-acoustic (DA) solitary structures in an unmagnetized dusty plasma, consisting of negatively charged mobile dust grains, Boltzmann distributed electrons, and nonthermally distributed ions of two distinct temperatures. The Korteweg-de Vries (K-dV), modified K-dV (mK-dV) and Gardner equations, and their solitary waves (SWs) and double layer (DL) (in case of Gardner equation) solutions are derived by using the reductive perturbation technique. The basic features of the DA Gardner solitons (GSs) and DLs are studied analytically as well as numerically. It has been observed that the GSs significantly differ from K-dV and mK-dV solitons, and only positive potential DLs exist in the system. It is also studied that two-temperature nonthermal ions significantly modify the nature and basic properties of the DA SWs. The present investigation can be very effective for understanding and studying the nonlinear characteristics of the DA waves in laboratory and space dusty plasmas.

Dust-ion-acoustic Gardner solitons in a dusty plasma with bi-Maxwellian electrons

The nonlinear propagation of dust-ion-acoustic (DIA) waves in a dusty plasma with bi-Maxwellian electrons, namely, lower and higher temperature electrons (composed of negatively charged stationary dust, inertial ions, and non-inertial two-temperature-electrons) is investigated by deriving the Gardner equation using the reductive perturbation technique. The basic features (amplitude, width, etc.) of the hump (positive potential) and dip (negative potential) shaped DIA solitons (Gardner solitons, i.e., GSs) are found to exist beyond the Korteweg-de Vries (K-dV) limit. These DIA-GSs are qualitatively different from the K-dV and modified K-dV solitons. It is also shown that depending on the parameter σ (where σ=Te1/Te2, Te1 and Te2 being the temperatures of two distinct electrons and Te1≪Te2), the DIA-GSs exhibit hump and dip shape solitary structures. The implications of our results in understanding the localized nonlinear electrostatic perturbations observed in double-plasma machines, rf discharge plasma, n...

Cylindrical and spherical dust-ion-acoustic modified Gardner solitons in dusty plasmas with two-temperature superthermal electrons

A rigorous theoretical investigation has been performed on the propagation of cylindrical and spherical Gardner solitons (GSs) associated with dust-ion-acoustic (DIA) waves in a dusty plasma consisting of inertial ions, negatively charged immobile dust, and two populations of kappa distributed electrons having two distinct temperatures. The well-known reductive perturbation method has been used to derive the modified Gardner (mG) equation. The basic features (amplitude, width, polarity, etc.) of nonplanar DIA modified Gardner solitons (mGSs) have been thoroughly examined by the numerical analysis of the mG equation. It has been found that the characteristics of the nonplanar DIA mGSs significantly differ from those of planar ones. It has been also observed that kappa distributed electrons with two distinct temperatures significantly modify the basic properties of the DIA solitary waves and that the plasma system under consideration supports both compressive and rarefactive DIA mGSs. The present investigation should play an important role for understanding localized electrostatic disturbances in space and laboratory dusty plasmas where stationary negatively charged dust, inertial ions, and superthermal electrons with two distinct temperatures are omnipresent ingredients.

Roles of superthermal electrons and positrons on positron-acoustic solitary waves and double layers in electron-positron-ion plasmas

Positron-acoustic (PA) solitary waves (SWs) and double layers (DLs) in four-component plasmas consisting of immobile positive ions, mobile cold positrons, and superthermal (kappa distributed) hot positrons and electrons are investigated both numerically and analytically by deriving Korteweg-de Vries (K-dV), modified K-dV (mK-dV), and Gardner equations along with their DLs solutions using the reductive perturbation method. It is examined that depending on the plasma parameters, the K-dV SWs, Gardner SWs, and DLs support either compressive or rarefactive structures, whereas mK-dV SWs support only compressive structure. It is also found that the presence of superthermal (kappa distributed) hot positrons and hot electrons significantly modify the basic features of PA SWs as well as PA DLs. Besides, the critical number density ratio of hot positrons and cold positrons play an important role in the polarity of PA SWs and DLs. The implications of our results in different space as well as laboratory plasma environments are briefly discussed.

Obliquely propagating dust-acoustic solitary waves in magnetized dusty plasmas with two-temperature Maxwellian ions

The nonlinear propagation of dust-acoustic waves in an obliquely propagating magnetized dusty plasma, containing Maxwellian distributed ions of distinct temperatures (namely lower and higher temperature Maxwellian ions), negatively charged mobile dust grains, and Maxwellian electrons, is rigorously investigated and analyzed by deriving the Zakharov-Kuznetsov equation. It is investigated that the characteristics of the dustacoustic solitary waves are significantly modified by the external magnetic field, relative ion and electron temperature-ratio, and respective number densities of two population of ions. The implications of the results obtained from this analysis in space and laboratory dusty plasmas are briefly discussed.

Effects of nonextensivity and nonthermality on dust-acoustic Gardner solitons in dusty plasmas with distinct ion temperatures

The effects of nonextensivity and nonthermality of ions of two distinct temperatures on dustacoustic Gardner solitons (DAGSs) in an unmagnetized dusty plasma system are investigated theoretically. The constituents of the dusty plasma under consideration are negatively charged mobile dust fluid, Boltzmann-distributed electrons, and ions of two distinct temperatures following nonextensive (q) and nonthermal distributions, respectively. The Korteweg-de Vries (KdV), modified KdV, and Gardner equations are derived by using the reductive perturbation technique, and thereby their characteristic features are compared. It is observed that both the nonextensive and nonthermal ions significantly modify the basic properties and polarities of dust-acoustic solitary waves. The present investigation may be of relevance to space and laboratory dusty plasma systems.

Instability Analysis of Obliquely Propagating Positron-Acoustic Solitary Waves in Superthermal Plasmas

The basic properties of the obliquely propagating positron-acoustic solitary waves (PASWs) and their multidimensional instability in magnetized electron-positron-ion plasmas consisting of immobile positive ions, mobile cold positrons, and superthermal (κ-distributed) hot positrons and electrons are investigated both numerically and analytically. By employing the reductive perturbation technique, the Zakharov-Kuznetsov equation is derived, which admits the solution of solitary waves. The fundamental features of PASWs are remarkably changed by the obliqueness, external magnetic field, superthermal parameter of electrons (κe), superthermal parameter of hot positrons (κp), ratio of the electron temperature to hot positron temperature (σ), ratio of the electron number density to cold positron number density (μe), and ratio of the hot positron number density to cold positron number density (μph). It is also found that the instability criterion and the growth rate are significantly modified by the external magnetic field and the propagation directions of both the nonlinear waves and their perturbation modes. This paper can be useful to understand the nonlinear electromagnetic perturbations in space and laboratory plasmas.

Dust-Acoustic Solitary Waves in a Magnetized Dusty Plasma With Ions Of Distinct Temperatures

A theoretical investigation has been made of obliquely propagating electrostatic solitary structures in a magnetized dusty plasma, composed of negatively charged dust, nonthermal ions of distinct temperatures, and Boltzmann distributed electrons. The properties of small but finite amplitude dust-acoustic solitary waves (DASWs) in this dusty plasma system are studied by deriving the Zakharov-Kuznetsov (ZK) equation. It has been inferred that the effects of obliqueness, external magnetic field, nonthermal ions of two distinct temperatures, and Boltzmann electrons cause modification of the characteristics (i.e., amplitude and width) of these solitary structures. The implications of our present investigation in understanding the basic features of nonlinear electrostatic perturbations observed in many space plasma systems and laboratory devices are briefly discussed.

Coexistence of DA shock and solitary waves in dusty plasmas with two-temperature ions

Summary form only given. The nonlinear propagation characteristics of cylindrical and spherical shock waves in an unmagnetized dusty plasma comprising of inertial negative dust, Boltzmann electrons, and ions with two distinct temperatures, are rigorously investigated by deriving the modified Burgers (mB) equation. Later, the nonplanar KdV-Burgers (nKdVB) equation is derived to show the presence of dispersive and dissipative effects on nonlinear waves. The standard reductive perturbation method is employed to derive the mB and nKdVB equations. The basic features of nonplanar dust-acoustic (DA) waves (viz. amplitude, profile structure, etc.) are discussed. The present analysis can play important role to understand the basic features of nonlinear electrostatic waves in astrophysical plasmas.