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| Pakistan Research Repository | Home |
Title of Thesis |
| Author(s) Qamar – Ul - Haque |
| Institute/University/Department Details Comsats Institute of Information Technology (CIIT), Islamabad, Pakistan |
| Session 2007 |
| Subject Physics |
| Number of Pages 98 |
| Keywords (Extracted from title, table of contents and abstract of thesis) linear dynamics, nonlinear dynamics, ion plasmas, vortices, coupled acoustic, electromagnetic drift, electron – positron – ion plasmas, nonlinear coherent structures |
Abstract The two dimensional large amplitude ion acoustic waves can give rise to dipolar vortex structures in magnetized homogeneous e-p-i plasmas as well. It is shown that in nonuniform plasmas the acoustic mode can couple with electrostatic drift waves and vortex-like nonlinear structures can be produced. A set of nonlinear equations is derived which describe the coupling of ion acoustic wave, Alfven wave and drift wave. These equations also give the stationary solution in the form of dipolar vortices. Linear dispersion relation of several coupled electrostatic and electromagnetic low frequency modes is also obtained. Linear and nonlinear Alfven waves are also studied in the presence of a background current gradient in e-p-i plasmas. The instability criterion becomes dependent upon the concentration of different species in a three component plasma. It is also pointed out that the drift waves can become unstable due to shear flow produced by externally applied electric field. The modified Rayleigh instability condition is obtained which is applicable to both electron-ion and e-p-i plasmas. It is proposed that the shear flow driven drift waves can be responsible for large amplitude electrostatic fluctuations in tokamak edges. A particular form of the shear flow can give rise to counter rotating vortices and vortex chains. A comparison of this work with the limiting cases of electron-ion and electron positron plasmas is also presented. It is pointed out that this investigation can be applicable to both astrophysical and laboratory plasmas. |
| Download Full Thesis |  5086.56 KB |
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| S. No. | Chapter | Title of the Chapters | Page | Size (KB) |
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| 1 | 0 | Contents | 412.3 KB |
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| 2 | 1 | Introduction | 5 | 707.31 KB |
| 1.1 | Linear And Nonlinear Dynamics Of Nonuniforn Electron – Positron – Ion Plasmas | 5 | ||
| 1.2 | Nonlinear Coherent Structures | 5 | ||
| 1.3 | Layout Of The Thesis | 12 | ||
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| 3 | 2 | Brief Overview Of The Vortices | 13 | 1317.43 KB |
| 2.1 | What Are Vortices | 13 | ||
| 2.2 | Types Of Vortices | 25 | ||
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| 4 | 3 | Linear And Nonlinear Drift Waves In E-P-I Plasmas | 36 | 585.35 KB |
| 3.1 | Introduction | 36 | ||
| 3.2 | Set Of Equations | 38 | ||
| 3.3 | Linear Dispersion Relation | 38 | ||
| 3.4 | Drift Wave Dipolar Vortices | 41 | ||
| 3.5 | Electrostatic Limit | 44 | ||
| 3.6 | Conclusions | 46 | ||
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| 5 | 4 | Coupled Acoustic And Drift Waves In E-P-E Plasmas | 47 | 707.42 KB |
| 4.1 | Acoustic And Electrostatic Drift Waves | 47 | ||
| 4.2 | Electromagnetic Drift And Acoustic Waves | 52 | ||
| 4.3 | Conclusions | 60 | ||
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| 6 | 5 | Current Gradient And Shear Flow Driven Vortices And Instabilities | 61 | 1012 KB |
| 5.1 | Basic Concept Of Instability | 61 | ||
| 5.2 | Drift Alfven Vortices With Current Gradient | 62 | ||
| 5.3 | Counter Rotating Vortices | 71 | ||
| 5.4 | Conclusion | 77 | ||
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| 7 | 6 | Summary | 81 | 203.83 KB |
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| 8 | 7 | References | 84 | 263.24 KB |
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