Browsing by Author "Dr. Zahida Ehsan, Assistant Profesor [Supervisor]"

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Formation Of Shock Like Structures In Rotating
(Publisher COMSATS University Islambad Lahore Campus, 2020) Anas Ahmad,; FA18-RPH-003; Dr. Zahida Ehsan, Assistant Profesor [Supervisor]; LHR TP 6357
Formation of Shock like Structures in Rotating and Viscous Pair Ion Plasma In this thesis we discuss non-linear effects in multi-component plasmas. Different types of solitary waves and soliton, are the main focus in this work. First of all we consider magneto sonic soliton propagating in external magnetic field in Electron-Positron-Ion plasma, using the effective one fluid MHD model. Two modes for the waves are discussed in the linear approximation by using the reductive perturbation scheme for these modes in the nonlinear regime. It is observed that for both the modes the angle, positron concentration, ion temperature, affect the propagation properties of solitary waves and are from those of the simple Electron-Ion plasmas. IAW is a low frequency electrostatic wave, which is supported by the ion inertia in plasma physics. Due to the compressions and rarefaction of ion number density these low frequency waves propagate in plasma. In the third chapter we investigate the linear and nonlinear properties of the IAW. The Zakharov-Kuznetsov equation is derived by employing again the reductive perturbation technique for this wave in the small amplitude nonlinear regime. This equation admits solitary wave solution. The amplitude and width of this solitary wave have been discussed with effects of obliqueness, relativity, ion temperature, positron concentration, magnetic field and rotation of the plasma. The distribution function decreases generally as a power law of the velocity instead of an exponential decrease associated with a Maxwellian distribution. A useful distribution to model plasma containing super thermal and super thermal particles is the generalized Lorentzian, or kappa, distribution function. The effect of particle trapping on the linear and nonlinear evolution of an ion acoustic wave in electron-ion plasmas has been discussed. The generalized KdV equations with associated solitary wave solutions for different ranges of parameter are derived by employing a perturbation technique. Dust acoustic wave on a very slow time scale of dust dynamics emerges as a result of the balance between dust grain inertia and plasma pressure. In chapter 4,The reductive perturbation method is used to drive Zakharov-Kuznetsov equation in relativistic, rotating, and magnetized electron-positron-ion non linear plasma. ZK equation acknowledge the solution of solitary wave.
Solar Wind Driven Kinetic Instability In The
(Publisher COMSATS University Islambad Lahore Campus, 2022) Muhammad Shafique; SP19-RPH-034; Dr. Zahida Ehsan, Assistant Profesor [Supervisor]; LHR TP 6373
Solar Wind driven Kinetic Instability in the Earth’s Magnetosphere by using non-Maxwellian kappa and (r, q) Distribution In this thesis, we have comparatively studied of fundamental mode by Using Boltzmann-Vlasov Kinetic model, a current less kinetic instability such as ion acoustic and dust-acoustic using non-Maxwellian distribution. The growth rate and the real frequency are calculated by using kappa (k) and generalized (r, q) distribution and result are compared with those of Maxwellian distribution. In an electrons-ions plasma following a non-Maxwellian generalized distribution function kappa (k) and (r, q), as shown a kinetic instability of ion-acoustic mode exist. In a three species (electrons, ions, dust) plasma following a non-Maxwellian generalized kappa (k) and (r, q) distribution function, as shown that a kinetic instability of dust-acoustic mode exists.