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dc.contributor.authorAkhtar, Naseem-
dc.description.abstractThe study of nonlinear wave propagation in plasmas is an emerging area of research to understand of energy or particle transport phenomenon in space, astrophysical and laboratory plasmas. In this work, modulational instability and envelope solitons excitations of electrostatic plasma waves in dilute plasmas are studied in the presence and absence of magnetic field in multicomponent plasmas. Envelope solitons are excited in a plasma medium when wave dispersion due to group velocity is balanced with nonlinearity of the medium. The excitation, propagation, stability of envelope modulated soliton structures and freak/rogue waves in different multicomponent plasmas are discussed. Plasma models comprised of electron-positron-ion, electronion- dust are considered with and without magnetic field for static and dynamic dust charged particles. Both positive and negative polarities of static charged dust particles are taken and studied their effects on propagation characteristics of nonlinear structures. The thermal (Maxwellian distribution) as well as nonthermal (kappa distributions function) for light mass plasmas species such as electrons and positrons, are considered to describe the excitations and stability of envelope solitons in space plasmas. The well known Krylov-Bogoliubov-Mitropolsky (KBM) method is applied to derive nonlinear Schrödinger equation (NLSE) for amplitude modulation of the plasma waves. This method is useful for explaining the long time behavior of the solution which consists of varying the wave amplitude so slowly that no secular term arises in the solution. The analytical and numerical investigations of NLSE are presented for different plasmas systems. The modulational instability and its growth rate are also discussed in detail. The stable and unstable regions for Ion acoustic wave (IAW), Dust-ion acoustic wave (DIAW), Dust-ion cyclotron wave (DICW), Dust acoustic wave (DAW) and Dust cyclotron wave (DCW) are investigated for the formation of dark or bright envelope solitons. The role of different plasma parameters like, plasmas density, temperature, spectral index, dust polarity, magnetic field and propagation angle on the stability of nonlinear envelope soliton structures are presented. The observations and propagation of fundamental rogue waves (RWs) and super RWs in space plasmas and in laboratory experiments are also pointed out.en_US
dc.description.sponsorshipHigher Education Commission Pakistanen_US
dc.publisherPakistan Institute of Engineering & Applied Sciences, Islamabad.en_US
dc.titleInvestigation of Envelope Solitons and Modulational Instability in Multicomponent Plasmasen_US
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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