The nonlinear propagation of electromagnetic (EM) waves in a pair plasma consisting of electron-positron (e-p) has been rigorously investigated in rotating astrophysical objects (e.g. pulsar magnetosphere). Two nonlinear approaches have been used to analyze the nonlinear wave phenomena in pulsar magnetosphere. The reductive perturbation method has been employed in order to derive the Korteweg-de Vries (K-dV) and derivative nonlinear Schrodinger equation (DNSE) as well as Wentzel, Kramers, and Brillouin (W.K.B) approximation technique has also been used to derive nonlinear Schrodinger equation (NLSE). The steady-state solutions of these nonlinear equations have been obtained and analyzed theoretically and numerically. The existence of solitary waves (SWs) in e-p plasma is found depending on the basic plasma parameters of considered e-p plasma. It has been seen that the basic features of SWs are significantly modified by the effects of rotational frequency (RF) and positron-to-electron thermal energy ratio (ER). The results, which have been found in this dissertation are summarized as follows: (i). e-p plasma medium supports low phase speed, high frequency, compressional e-p Alfven (CEPA) waves, and shear e-p Alfven (SEPA) waves; (ii). Both the amplitude and the width of CEPA, and SEPA SWs are seen to increase with the increase of ER. It is investigated that the RF does not have any influence on the amplitude and width of the K-dV and DNSE SWs observed in the e-p plasma of crab pulsar but the RF has a significant effect on the basic properties of SWs obtained via NLSE; (iii). The frequency of EM waves propagated in the crab pulsar lies in the range of radio waves. It is also observed that the phase speed of the EM waves increases with the decreasing values of the angle between the magnetic moment and the rotational axis, and waves are modulationally unstable when W.K.B technique has been used. The findings of these investigations may use to understand the nonlinear EM waves phenomena in rotating astrophysical and laboratory plasmas.
Table of Contents
1 Introduction
1.1 Concept of Plasma
1.1.1 The Evolution of Plasma Physics
1.1.2 Plasma Characteristics
1.1.3 Classification of Plasmas
1.1.4 Occurrences of Plasmas
1.1.5 Applications of Plasmas
1.2 Electron-Positron Plasmas
1.2.1 Occurrences Electron-Positron Plasmas
1.3 Different Plasma Waves Phenomena
1.3.1 Short Notes on Alfvén Waves
1.3.2 Types of Alfvén Waves
1.4 Rotating Astrophysical Objects
1.5 Linearity and Nonlinearity of Waves
1.6 Existing Theoretical Nonlinear Approach
1.7 Nonlinear Wave Phenomena
1.8 Layout of The Book
2 Nonlinear Compressional Alfvén Waves in a Pair Plasma
2.1 Introduction
2.2 Governing Equations
2.3 Derivation of The K-dV Equation
2.4 Solution of The K-dV Equation
2.5 Numerical Analysis
2.6 Discussion
3 Nonlinear Solitary Waves in a Pair Plasma
3.1 Introduction
3.2 Governing Equations
3.3 Derivation of NLSE
3.4 Numerical Analysis
3.5 Modulational Instability
3.6 Discussion
4 Nonlinear Shear Alfvén Waves in a Pair Plasma
4.1 Introduction
4.2 The Mathematical Model
4.3 Derivation of The DNSE
4.4 Solution of The DNSE Equation
4.5 Numerical Analysis and Results
4.6 Conclusion
5 Summary
6 Appendix
6.1 Maxwell’s Equation in a Rotating Frame
6.2 Solution of the Korteweg-de Vries (K-dV) Equation
Research Objectives and Topics
This thesis investigates the characteristics of solitary waves and nonlinear propagation phenomena in electron-positron (e-p) plasmas, specifically within the environments of rotating astrophysical objects like pulsar magnetospheres. The research aims to analyze how plasma parameters, such as rotational frequency and thermal energy ratios, influence the amplitude, width, and stability of these waves using theoretical models and numerical analysis.
- Nonlinear propagation of electromagnetic waves in electron-positron plasmas.
- Theoretical derivation of K-dV, NLSE, and DNSE models for plasma waves.
- Influence of pulsar rotation and relativistic effects on wave characteristics.
- Investigation of compressional and shear Alfvén solitons in pair plasma.
Excerpt from the Book
1.1 Concept of Plasma
In the mid-19th century the Czech physiologist Jan Evangelista Purkinje introduced use of the Greek word plasma to denote the clear fluid which remains after removal of all the corpuscular material in blood. Half a century later, the American scientist Irving Langmuir proposed in 1922 that the electrons, ions, and neutrals in an ionized gas could similarly be considered as corpuscular material entrained in some kind of fluid medium and called this entraining medium plasma. However, it turned out that unlike blood where there really is a fluid medium carrying the corpuscular material, there actually is no fluid medium entraining the electrons, ions, and neutrals in an ionized gas [1].
Ionized gas is called plasma but any ionized gas can not be called plasma, of course; there is always some degree of ionization in any gas. There are some basic criteria that are required for being plasma formation. These criteria are necessary to distinguish between an ionized gas and plasma itself. The basic criteria, namely, charge-neutrality (“macroscopical neutrality”), collective behaviour, and collision condition.
Summary of Chapters
1 Introduction: Provides an overview of plasma properties, electron-positron pair plasmas, and the fundamental concepts of nonlinear wave dynamics.
2 Nonlinear Compressional Alfvén Waves in a Pair Plasma: Investigates the propagation of high-frequency compressional waves in rotating pair plasmas using the K-dV equation.
3 Nonlinear Solitary Waves in a Pair Plasma: Explores intense electromagnetic wave propagation and modulational instability in ultra-relativistic magnetized pulsar magnetospheres via the NLSE.
4 Nonlinear Shear Alfvén Waves in a Pair Plasma: Analyzes shear Alfvén solitons and their properties in rotating electron-positron plasmas using the derivative nonlinear Schrödinger equation (DNSE).
5 Summary: Summarizes the key research findings and theoretical contributions presented in the preceding chapters.
6 Appendix: Details the mathematical derivations, including Maxwell's equations in rotating frames and specific solutions to the Korteweg-de Vries (K-dV) equation.
Keywords
Electron-Positron Plasma, Pulsar Magnetosphere, Solitary Waves, Solitons, Nonlinear Dynamics, Alfvén Waves, K-dV Equation, NLSE, DNSE, Plasma Physics, Relativistic Plasma, Rotational Frequency, Modulational Instability, Electromagnetic Waves, Pair Plasma
Frequently Asked Questions
What is the primary focus of this thesis?
This research primarily focuses on the theoretical investigation of nonlinear electromagnetic wave propagation, specifically solitary waves, within rotating astrophysical environments such as pulsar magnetospheres containing electron-positron pair plasmas.
What are the central themes discussed in the work?
The core themes include the formation and evolution of solitary waves (solitons) in relativistic plasma, the impact of extreme rotation on these structures, and the mathematical modeling of these phenomena using reductive perturbation methods.
What is the primary research goal?
The goal is to determine how intrinsic plasma parameters, such as the positron-to-electron thermal energy ratio and the rotational frequency of pulsars, modify the basic properties of solitary waves like amplitude, width, and stability.
Which scientific methods are employed?
The thesis utilizes fluid dynamical models, relativistic magnetohydrodynamic (MHD) equations, and theoretical techniques such as the Reductive Perturbation Method (RPM) to derive nonlinear evolution equations like the K-dV, NLSE, and DNSE.
What does the main body of the work cover?
The main body examines three distinct nonlinear scenarios: compressional Alfvén waves, intense electromagnetic solitary waves, and shear Alfvén waves, all within the specific context of relativistic, rotating, and magnetized pair plasmas.
Which keywords best characterize this research?
Key terms include Electron-Positron Plasma, Pulsar Magnetosphere, Solitary Waves, Nonlinear Dynamics, Alfvén Waves, and Rotational Astrophysical Objects.
How does the rotation of a pulsar affect solitary waves?
The study finds that while rotation is a critical factor for the plasma environment, specific solitary wave features like amplitude and width are influenced by rotational frequency in distinct ways depending on the type of wave and the model applied, often exhibiting significant effects in high-rotation pulsar environments.
What is the significance of the "pair plasma" in this study?
Pair plasma, consisting of electrons and positrons with equal mass and opposite charge, exhibits unique collective behavior that differs significantly from standard electron-ion plasmas, making it essential for understanding astrophysical phenomena like gamma-ray bursts and pulsar emission.
- Arbeit zitieren
- Tanvir Islam Rajib (Autor:in), 2015, Nonlinear Phenomena in Rotating Astrophysical Objects, München, GRIN Verlag, https://www.grin.com/document/418560
