Electromagnetic wave instability in a relativistic electron-positron-ion plasma (original) (raw)
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Instability of electromagnetic R-mode waves in a relativistic plasma
Physics of Plasmas, 1998
An explicit mathematical formalism is developed to evaluate the growth rate of field-aligned electromagnetic R-mode waves in a relativistic plasma. The methodology is valid for weak wave growth or damping when the resonant relativistic electrons comprise a small portion of the total plasma population. Numerical results are obtained for realistic plasma parameters using three distinct distribution functions for the relativistic electron population. Wave growth rates obtained by numerical integration along the resonant relativistic ellipse are shown to be substantially smaller than calculations performed under the nonrelativistic approximation. The relativistic corrections are primarily due to a reduction in the resonant electron anisotropy. Changes from the standard nonrelativistic treatment are noticeable at relatively small electron thermal energies ͑a few keV͒, and they become very significant for thermal energies above 100 keV, especially in low density regions where the plasma frequency is comparable to or lower than the electron gyrofrequency. The results have applications to wave instability in the outer radiation belts of the Earth, the inner Jovian magnetosphere, and other space plasmas where relativistic electrons are present.
Astrophysics and Space Science, 1980
The modulational instability of the weakly nonlinear longitudinal Langmuir as well as the transverse electromagnetic waves, propagation in the relativistic plasma without the static fields is described. The nonlinear Schr6dinger equation taking account of the nonlinear Landau damping for these waves has been derived by means of the relativistic Vlasov and Maxwell equations. The plasma with the weakly relativistic temperature and that with an ultrarelativistic one has been investigated. In the first case, for the electron-proton plasma with the temperature more than 2.3 KeV we found the regional change of the wave numbers for which the soliton of two types, subsonic and supersonic, can exist. The soliton of the transverse waves can exist when the group velocity of the waves is between the thermal velocity of the electron and ion and the length of the linear waves is less than 27rc/o~p~. In the second case the regions of the wave numbers, with the solitons of the Langmuir and transverse waves have been determined. The nonlinear waves in the electron-positron plasma and the waves with the phase velocity, which is about the light one, are also considered in the following paper.
Journal of Experimental and Theoretical Physics Letters, 2004
The nonlinear interaction between the electron-positron pairs produced by an electromagnetic wave in plasma and the wave leads to damping of the wave, frequency upshift, change of polarization, and particle acceleration. The case of a circularly polarized wave is investigated in the framework of the relativistic Vlasov equation with a source term based on the Schwinger formula for the pair creation rate.
Nonlinear Low Frequency Wave Phenomena in Space Plasmas
Space is endowed with a rich variety of electrodynamic phenomena. Much of known matter in the universe exists as plasmas. Plasmas occur naturally, predominantly occupy the Sun, Stars, Auroras and Interstellar space. The solar wind is a stream of energized, charged particles (i.e., electrons and protons, along with few heavier ions), flowing outward from the Sun, through the solar system at a very high speed and temperature. Once the solar wind has blown into space, the particles travel all the way past planet Pluto and do not slow down until they reach the termination shock within the heliosphere. Because of the author's interest in space electrodynamics phenomena, the focus of this thesis is " Nonlinear low frequency wave phenomena in space plasmas". In the name of Allah, the Beneficent and the Merciful. I would like to express my sincere appreciation and gratitude to the following people, departments and institutions, without whose involvement this work would not been possible. • My supervisor, Prof. Ramesh Bharuthram for his expert guidance, fatherly advice and encouragement.
Some recent developments in nonlinear relativistic plasma dynamics
2002
Some recent developments in the analytical and numerical study of the interaction of ultra-intense ultra-short laser pulses with relativistic plasmas are reviewed. Special attention is given to the subject of ion acceleration in view of its applications which range from proton imaging to the acceleration of collimated ion bunches and to the effect of fast magnetic field line reconnection on the evolution of the self-generated magnetic field.
Large-amplitude electromagnetic waves in magnetized relativistic plasmas with temperature
Nonlinear Processes in Geophysics, 2014
Propagation of large-amplitude waves in plasmas is subject to several sources of nonlinearity due to relativistic effects, either when particle quiver velocities in the wave field are large, or when thermal velocities are large due to relativistic temperatures. Wave propagation in these conditions has been studied for decades, due to its interest in several contexts such as pulsar emission models, laser-plasma interaction, and extragalactic jets.
Physical Review E, 2012
We develop a nonlinear theory for self-modulation of a circularly polarized electromagnetic wave in a relativistic hot weakly magnetized electron-positron plasma. The case of parallel propagation along an ambient magnetic field is considered. A nonlinear Schrödinger equation is derived for the complex wave amplitude of a selfmodulated wave packet. We show that the maximum growth rate of the modulational instability decreases as the temperature of the pair plasma increases. Depending on the initial conditions, the unstable wave envelope can evolve nonlinearly to either periodic wave trains or solitary waves. This theory has application to high-energy astrophysics and high-power laser physics.
Physical Review E, 2012
The propagation of circularly polarized electromagnetic waves along a constant background magnetic field in an electron-positron plasma is calculated by means of both a fluid and a kinetic theory treatment. In the fluid theory, relativistic effects are included in the particle motion, the wave field, and in the thermal motion by means of a function f , which depends only on the plasma temperature. In this work we analyze the consistency of the fluid results with those obtained from a kinetic treatment, based on the relativistic Vlasov equation. The corresponding kinetic dispersion relation is numerically studied for various temperatures, and results are compared with the fluid treatment. Analytic expressions for the Alfvén velocity are obtained for the fluid and kinetic models, and it is shown that, in the kinetic treatment, the Alfvén branch is suppressed for large temperatures.