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Plasma Science and Technology 2015年第3期17卷 177-182页

作者： M.R.HOSSEN a.a.mamun Department of Natural Sciences Daffodil International University Department of Physics Jahangirnagar University

A theoretical study on the nonlinear propagation of nonplanar （cylindrical and spherical） electrostatic modified ion-acoustic （mIA） shock structures has been carried out in an unmagnetized, collisionless four component degenerate plasma system （containing degenerate electron fluids, inertial positively as well as negatively charged light ions, and positively charged static heavy ions）. This investigation is valid for both non-relativistic and ultra-relativistic limits. The modified Burgers （mB） equation has been derived by employing the reductive perturbation method, and used to numerically analyze the basic features of shock structures. It has been found that the effects of degenerate pressure and number density of electron and inertial positively as well as negatively charged light ion fluids, and various charging state of positively charged static heavy ions significantly modify the basic features of mIA shock structures. The implications of our results to dense plasmas in astrophysical compact objects （e.g., non-rotating white dwarfs, neutron stars, etc.） are briefly discussed.

关键词： modified ion-acoustic waves shock waves nonplanar geometry relativistic effect degenerate pressure

Ion-Acoustic Shock Waves in Nonextensive Multi-Ion Plasmas

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Communications in Theoretical Physics 2015年第10期64卷 479-484页

作者： N.Jannat M.Ferdousi a.a.mamun Department of Physics Jahangirnagar University

The nonlinear propagation of ion-acoustic(IA) shock waves(SHWs) in a nonextensive multi-ion plasma system(consisting of inertial positive light ions as well as negative heavy ions, noninertial nonextensive electrons and positrons) has been studied. The reductive perturbation technique has been employed to derive the Burgers *** basic properties(polarity, amplitude, width, etc.) of the IA SHWs are found to be significantly modified by the effects of nonextensivity of electrons and positrons, ion kinematic viscosity, temperature ratio of electrons and positrons, *** has been observed that SHWs with positive and negative potential are formed depending on the plasma *** findings of our results obtained from this theoretical investigation may be useful in understanding the characteristics of IA SHWs both in laboratory and space plasmas.

关键词： ion-acoustic shock waves electron-positron-ion pla

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

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Chinese Physics B 2013年第11期22卷 390-395页

作者： M.S.Alam M.M.Masud a.a.mamun Department of Physics Jahangirnagar University Department of Physics Bangladesh University of Engineering and Technology (BUET)

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 investi- gated 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.

关键词： bi-kappa electrons shock waves dust-ion-acoustic waves dusty plasma

Time-Dependent Cylindrical and Spherical Solitary Structures and Double Layers of Dust Ion-Acoustic Waves in Ultra-Relativistic Dense Plasma

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Communications in Theoretical Physics 2013年第6期59卷 745-750页

作者： T.Akhter M.M.Hossain a.a.mamun Department of Physics Jahangirnagar University

Cylindrical and spherical (nonplanar) solitary waves (SWs) and double layers (DLs) in a multi-ion plasma system (containing inertial positively as well as negatively charged ions, non-inertial degenerate electrons, and negatively charged static dust) are studied by employing the standard reductive perturbation method. The modified Gardner (MG) equation describing the nonlinear propagation of the dust ion-acoustic (DIA) waves is derived, and its nonplanar SWs and DLs solutions are numerically analyzed. The parametric regimes for the existence of SWs, which are associated with both positive and negative potential, and DLs which are associated with negative potential, are obtained. The basic features of nonplanar DIA SWs, and DLs, which are found to be different from planar ones, are also identified.

关键词： solitary waves double layers ultra-relativistic dense plasma dust ion acoustic waves Gardnerequation

Nonplanar Shock Structures in a Relativistic Degenerate Multi-Species Plasma

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Communications in Theoretical Physics 2014年第12期61卷 888-894页

作者： M.R.Hossen S.A.Ema a.a.mamun Department of Natural Sciences Daffodil International University Sukrabad Dhaka-1207 Bangladesh Department of Physics Jahangirnagar University Savar Dhaka-1342 Bangladesh

A nonlinear propagation of cylindrical and spherical modified ion-acoustic(m IA) waves in an unmagnetized,collisionless, relativistic, degenerate multi-species plasma has been investigated theoretically. This plasma system is assumed to contain non-relativistic degenerate light ions, both non-relativistic and ultra-relativistic degenerate electron and positron fluids, and arbitrarily charged static heavy ions. The restoring force is provided by the degenerate pressures of the electrons and positrons, whereas the inertia is provided by the mass of ions. The arbitrarily charged static heavy ions participate only in maintaining the quasi-neutrality condition at equilibrium. The modified Burgers(m B) equation is derived by using reductive perturbation technique and numerically analyzed to identify the basic features of m IA shock structures. The basic characteristics of m IA shock waves are found to be significantly modified by the effects of degenerate pressures of electron, positron, and ion fluids, their number densities, and various charge state of heavy ions. The implications of our results to dense plasmas in astrophysical compact objects(e.g., non-rotating white dwarfs,neutron stars, etc.) are briefly discussed.

关键词： modified ion-acoustic waves shock waves degenerate pressure relativity compact objects

Electrostatic Nonplanar Positron-Acoustic Shock Waves in Superthermal Electron-Positron-Ion Plasmas

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Communications in Theoretical Physics 2015年第6期63卷 754-760页

作者： M.J.Uddin M.S.Alam a.a.mamun Department of Physics Jahangirnagar University

The basic properties of the nonlinear propagation of the nonplanar （cylindrical and spherical） positronacoustic （PA） shock waves （SHWs） in an unmagnetized electron-positron-ion （e-p-i） plasma containing immobile positive ions, mobile cold positrons, and superthermal （kappa distributed） hot positrons and electrons are investigated both analytically and numerically. The modified Burgers equation （roBE） is derived by using the reductive perturbation method. The basic features of PA SHWs are significantly modified by the cold positron kinematic viscosity （U）, superthermal parameter of electrons （ke）, superthermal parameter of hot positrons （kp）, the ratio of the electron temperature to hot positron temperature （or）, the ratio of the electron number density to cold positron number density （μe）, and the ratio of the hot positron number density to cold positron number density （μph）. This study could be useful to identify the basic properties of nonlinear electrostatic disturbances in dissipative space and laboratory plasmas.

关键词： positron-acoustic waves superthermal particles Kappa distribution shock waves modified Burg-ers equation electron-positronion plasmas

Modulated Dust-Acoustic Wave Packets in an Opposite Polarity Dusty Plasma System

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Communications in Theoretical Physics 2019年第3期71卷 327-333页

作者： S.Jahan N.A.Chowdhury A.Mannan a.a.mamun Department of Physics Jahangirnagar University

The nonlinear propagation of the dust-acoustic bright and dark envelope solitons in an opposite polarity dusty plasma(OPDP) system(composed of non-extensive q-distributed electrons, iso-thermal ions, and positively as well as negatively charged warm dust) has been theoretically investigated. The reductive perturbation method(which is valid for a small, but finite amplitude limit) is employed to derive the nonlinear Schr¨odinger equation. Two types of modes, namely, fast and slow dust-acoustic(DA) modes, have been observed. The conditions for the modulational instability(MI) and its growth rate in the unstable regime of the DA waves are significantly modified by the effects of non-extensive electrons, dust mass, and temperatures of different plasma species, etc. The implications of the obtained results from our current investigation in space and laboratory OPDP medium are briefly discussed.

关键词： dust-acoustic waves opposite polarity modulational instability envelope solitons

Cylindrical and Spherical Electron-Acoustic Shock Waves in Electron-Positron-Ion Plasmas with Nonextensive Electrons and Positrons

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Communications in Theoretical Physics 2015年第2期63卷 243-248页

作者： A.Rafat M.M.Rahman M.S.Alam a.a.mamun Department of Physics Jahangirnagar University

Electron-acoustic shock waves （EASWs） in an unmagnetized four-component plasma （containing hot elec- trons and positrons following the q-nonextensiv.e distribution, cold mobile viscous electron fluid, and immobile positive ions） are studied in nonplanar （cylindrical and spherical） geometry. With the help of the reductive perturbation method, the modified Burgers equation is derived. Analytically, the effects of nonplanar geometry, nonextensivity, relative number density and temperature ratios, and cold electron kinematic viscosity on the basic properties （viz. amplitude, width, speed, etc.） of EASWs are discussed. It is exarmined that the EASWs in nonplanar geometry significantly differ from those in planar geometry. The results of this investigation can be helpful in understanding the nonlinear features of EASWs in various astrophysical plasmas.

关键词： electron-acoustic shock waves electron-positron-ion plasmas modified Burgers equation nonpla-nar geometry nonextensivity

Solitary Potential in a Space Plasma Containing Dynamical Heavy Ions and Bi-Kappa Distributed Electrons of Two Distinct Temperatures

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Communications in Theoretical Physics 2018年第1期69卷 107-114页

作者： M.Sarker B.Hosen M.R.Hossen a.a.mamun Department of Physics Jahangirnagar University Department of General Educational Development Daffodil International University

The heavy ion-acoustic solitary waves(HIASWs) in a magnetized, collisionless, space plasma system(containing dynamical heavy ions and bi-kappa distributed electrons of two distinct temperatures) have been theoretically investigated. The Korteweg-de Vries(K-dV), modified K-dV(MK-dV), and higher-order MK-dV(HMK-dV) equations are derived by employing the reductive perturbation method. The basic features of HIASWs(viz. speed, polarity,amplitude, width, etc.) are found to be significantly modified by the effects of number density and temperature of different plasma species, and external magnetic field(obliqueness). The K-dV and HM-Kd V equations give rise to both compressive and rarefactive solitary structures, whereas the MK-dV equation supports only the compressive solitary structures. The implication of our results in some space and laboratory plasma situations are briefly discussed.

关键词： heavy ion acoustic waves solitary waves superthermal electrons higher order nonlinear equations

Instability Analysis of Positron-Acoustic Waves in a Magnetized Multi-Species Plasma

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Communications in Theoretical Physics 2017年第4期67卷 458-466页

作者： M.A.Hossen M.G.Shah M.R.Hossen a.a.mamun Department of Physics Jahangirnagar UniversitySavarDhaka-1342Bangladesh Department of Physics Hajee Mohammad Danesh Science and Technology UniversityDinajpur-5200Bangladesh Department of General Educational Development Daffodil International UniversitySukrabadDhaka-1207Bangladesh

The nonlinear propagation of electrostatic excitations and their multi-dimensional instability in a magnetized, degenerate electron-positron-ion(EPI) plasma system(containing inertial cold positrons, relativistic degenerate electrons and hot positrons, and negatively charged immobile heavy ions) are theoretically investigated. The reductive perturbation method is employed to derive the Zakharov–Kuznetsov equation which admits a localized solitary wave solution for small but finite amplitude limit, and the multi-dimensional instability of the positron acoustic solitary waves(PASWs) is studied by the small-k perturbation expansion method. It is found that the basic characteristics(viz. phase speed, amplitude, width) of the PASWs are significantly affected by the degree of obliqueness, relativistic degeneracy,and plasma particle number densities. The instability criterion and its growth rate, which are depending on the magnetic field and the propagation directions of both the PASWs, and their perturbation modes are discussed. The present analysis can be helpful in understanding the nonlinear phenomenon in dense astrophysical as well as space plasma systems,especially in pulsar environments.

关键词： instability analysis solitary waves magnetized plasma degeneracy relativistic effect