Asit Saha

Bio: Asit Saha is an academic researcher from Sikkim Manipal University. The author has contributed to research in topics: Acoustic wave & Ion acoustic wave. The author has an hindex of 23, co-authored 89 publications receiving 1412 citations. Previous affiliations of Asit Saha include Visva-Bharati University.

Bifurcations of dust ion acoustic travelling waves in a magnetized dusty plasma with a q-nonextensive electron velocity distribution

Abstract: Nonlinear ion acoustic waves in the magnetized dusty plasma in the presence of superthermal electron have been studied. We have used the reductive perturbation method to derive a Kadomtsev-Petviashili equation for dust ion acoustic waves in a magnetized dusty plasma with q-nonextensive velocity distributed electrons. By applying the bifurcation theory of planar dynamical systems to this equation, the existence of solitary wave solutions and periodic travelling wave solutions is proved. Two exact solutions of the above waves are obtained.

Bifurcations of nonlinear ion acoustic travelling waves in the frame of a Zakharov-Kuznetsov equation in magnetized plasma with a kappa distributed electron

Abstract: Bifurcations of nonlinear propagation of ion acoustic waves (IAWs) in a magnetized plasma whose constituents are cold ions and kappa distributed electron are investigated using a two component plasma model. The standard reductive perturbation technique is used to derive the Zakharov-Kuznetsov (ZK) equation for IAWs. By using the bifurcation theory of planar dynamical systems to this ZK equation, the existence of solitary wave solutions and periodic travelling wave solutions is established. All exact explicit solutions of these travelling waves are determined. The results may have relevance in dense space plasmas.

Solitonic, periodic, quasiperiodic and chaotic structures of dust ion acoustic waves in nonextensive dusty plasmas

Abstract: The solitonic, periodic, quasiperiodic and chaotic structures of dust ion acoustic waves in an unmagnetized dusty plasma with q-nonextensive electrons are studied using the bifurcation theory of planar dynamical systems through direct approach. Using Galilean transformation, model equations are transformed to a planar dynamical system. We obtain all possible phase portraits of the planar dynamical system and corresponding solitary and periodic wave solutions depending on parameters q and μ. Considering an external periodic perturbation, the quasiperiodic and chaotic behaviors of dust ion acoustic waves are presented. The effect of q, the nonextensive parameter is found to have significant effect on quasiperiodic and chaotic motions of dust ion acoustic waves. To show these we study the behavior of dust ion acoustic waves for several values of q, keeping the other plasma parameters like μ and v fixed. It is seen that the unperturbed dynamical system has the solitary and periodic wave solutions, but the perturbed dynamical system has quasiperiodic and chaotic motions for same values of parameters q,μ and v.

Dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons

Abstract: The dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons has been investigated in the framework of perturbed and non-perturbed Kadomtsev-Petviashili (KP) equations. Applying the reductive perturbation technique, we have derived the KP equation in electron-positron-ion magnetoplasma with kappa distributed electrons and positrons. Bifurcations of ion acoustic traveling waves of the KP equation are presented. Using the bifurcation theory of planar dynamical systems, the existence of the solitary wave solutions and the periodic traveling wave solutions has been established. Two exact solutions of these waves have been derived depending on the system parameters. Then, using the Hirota's direct method, we have obtained two-soliton and three-soliton solutions of the KP equation. The effect of the spectral index κ on propagations of the two-soliton and the three-soliton has been shown. Considering an external periodic perturbation, we have presented the quasi periodic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas.

Differential Equations and Dynamical Systems

Abstract: Series Preface * Preface to the Third Edition * 1 Linear Systems * 2 Nonlinear Systems: Local Theory * 3 Nonlinear Systems: Global Theory * 4 Nonlinear Systems: Bifurcation Theory * References * Index

Waves in Dusty Space Plasmas

Abstract: Preface. 1. Plasmas and Dust. 2. Charging Mechanisms and Experiments. 3. Space Observations. 4. Multispecies Formalism and Waves. 5. Electrostatic Modes. 6. Electromagnetic Modes. 7. Fluctuating Dust Charges. 8. Self-Gravitation. 9. Mass and Size Distributions. 10. Other Modes. 11. Conclusions and Outlook. Bibliography. Index.

The New Class of Dusty DAZ White Dwarfs

Abstract: Our mid-infrared survey of 124 white dwarfs with the Spitzer Space Telescope and the IRAC imager has revealed an infrared excess associated with the white dwarf WD 2115-560 naturally explained by circumstellar dust. This object is the fourth white dwarf observed to have circumstellar dust. All four are DAZ white dwarfs, i.e. they have both photospheric Balmer lines and photospheric metal lines. We discuss these four objects as a class, which we abbreviate "DAZd", where the "d" stands for "dust". Using an optically-thick, geometrically-thin disk model analogous to Saturn's rings, we find that the inner disk edges are at >~0.1 to 0.2 Ro and that the outer disk edges are ~0.3 to 0.6 Ro. This model naturally explains the accretion rates and lifetimes of the detected WD disks and the accretion rates inferred from photospheric metal abundances.

Dromion-like soliton interactions for nonlinear Schrödinger equation with variable coefficients in inhomogeneous optical fibers

Abstract: In this paper, a generalized nonlinear Schrodinger equation with variable coefficients is investigated. According to the analytic soliton solutions, the dromion-like structures between soliton interactions are revealed, and interaction properties are discussed. By changing the values of gain/loss, group velocity dispersion and self-phase modulation parameters, influences of them on interaction intensity and phase of solitons are presented. Besides, methods of controlling the path and spacing of solitons are suggested. Results of this paper may be potential valuable to the study of soliton interactions in inhomogeneous optical fibers and have applications in all-optical switches.