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Modeling of magnetized collisional plasma sheath with nonextensive electron distribution and ionization source

Plasma Science and Technology 2023年第3期25卷 21-31页

作者：陈龙杨叶慧安宇豪段萍孙少娟崔作君阚子晨高维富 School of Science Dalian Maritime UniversityDalian 116026People’s Republic of China

The properties of an atmospheric-pressure collisional plasma sheath with nonextensively distributed electrons and hypothetical ionization source terms are studied in this work. The Bohm criterion for the magnetized plasma is extended in the presence of an ion–neutral collisional force and ionization source. The effects of electron nonextensive distribution, ionization frequency, ion–neutral collision, magnetic field angle and ion temperature on the Bohm criterion of the plasma sheath are numerically analyzed. The fluid equations are solved numerically in the plasma–wall transition region using a modified Bohm criterion as the boundary condition. The plasma sheath properties such as charged particle density, floating sheath potential and thickness are thoroughly investigated under different kinds of ion source terms, contributions of collisions, and magnetic fields. The results show that the effect of the ion source term on the properties of atmosphericpressure collisional plasma sheath is significant. As the ionization frequency increases, the Mach number of the Bohm criterion decreases and the range of possible values narrows. When the ion source is considered, the space charge density increases, the sheath potential drops more rapidly,and the sheath thickness becomes narrower. In addition, ion–neutral collision, magnetic field angle and ion temperature also significantly affect the sheath potential profile and sheath thickness.

关键词： plasma sheath Bohm criterion nonextensivity ionization source

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Unstable mode of ion-acoustic waves with two temperature q-nonextensive distributed electrons

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Chinese Physics B 2021年第9期30卷 313-319页

作者： S Bukhari Nadeem Hussain S Ali Department of Physics The University of Azad Jammu and KashmirMuzaffarabad 13100Azad KashmirPakistan National Center for Physics at QAU Campus Shahdra Valley RoadIslamabad 44000Pakistan

The linear characteristics of the unstable mode of ion-acoustic waves are examined in an electrostatic electron-ion plasma composed of streaming hot electrons,non-streaming cold electrons and dynamical positive *** plasma under consideration is modeled by using a non-gyrotropic nonextensive q-distribution function in which the free energy source for wave excitation is provided by the relative directed motion of streaming hot electrons with respect to the other plasma *** the frame work of kinetic model,a linearized set of Vlasov-Poisson's equations are solved to obtain the analytical expressions for dispersion relation and Landau damping *** threshold condition for the unstable ion-acoustic wave is derived to assess the stability of the wave in the presence of nonextensive *** in the wave spectrum and nontrivial effects of q-nonextensive parameter on the ion-acoustic waves can be of interest for the readers in the regions of Saturns's magnetosphere.

关键词： non-gyrotropic nonextensivity Saturns's magnetosphere

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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

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Instability of Thermally Conducting Self-Gravitating Systems

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Journal of Modern Physics 2010年第1期1卷 77-82页

作者： Shaista Shaikh Aiyub Khan 不详

The gravitational instability of a thermally conducting self-gravitating system permeated by a uniform and oblique magnetic field has been analyzed in the framework of Tsallis’ nonextensive theory for possible mod-ifications in the Jeans’ instability criterion. It is concluded that the instability criterion is indeed modified into one that depends explicitly on the nonextensive parameter. The influence of thermal conductivity on the system stability is also examined.

关键词： Jeans’ Criterion nonextensivity Thermally Conducting Self-Gravitating

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The Burr XII Distribution Family and the Maximum Entropy Principle: Power-Law Phenomena Are Not Necessarily “Nonextensive”

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Open Journal of Statistics 2015年第7期5卷 730-741页

作者： F. Brouers Institute of Physics University of Liège Liège Belgium

In this paper, we recall for physicists how it is possible using the principle of maximization of the Boltzmann-Shannon entropy to derive the Burr-Singh-Maddala (BurrXII) double power law probability distribution function and its approximations (Pareto, loglogistic.) and extension (GB2…) first used in econometrics. This is possible using a deformation of the power function, as this has been done in complex systems for the exponential function. We give to that distribution a deep stochastic interpretation using the theory of Weron et al. Applied to thermodynamics, the entropy nonextensivity can be accounted for by assuming that the asymptotic exponents are scale dependent. Therefore functions which describe phenomena presenting power-law asymptotic behaviour can be obtained without introducing exotic forms of the entropy.

关键词： Buur XII Distribution Singh-Maddala Distribution Lévy Function Entropy Non-Equilibrium Thermodynamics Complex Systems nonextensivity

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