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Title: Parametric decays in relativistic magnetized electron-positron plasmas with relativistic temperatures

Abstract

The nonlinear evolution of a circularly polarized electromagnetic wave in an electron-positron plasma propagating along a constant background magnetic field is considered, by studying its parametric decays. Relativistic effects, of the particle motion in the wave field and of the plasma temperature, are included to obtain the dispersion relation of the decays. The exact dispersion relation of the pump wave has been previously calculated within the context of a relativistic fluid theory and presents two branches: an electromagnetic and an Alfven one. We investigate the parametric decays for the pump wave in these two branches, including the anomalous dispersion zone of the Alfven branch where the group velocity is negative. We solve the nonlinear dispersion relation for different pump wave amplitudes and plasma temperatures, finding various resonant and nonresonant wave couplings. We are able to identify these couplings and study their behavior as we modify the plasma parameters. Some of these couplings are suppressed for larger amplitudes or temperatures. We also find two kinds of modulational instabilities, one involving two sideband daughter waves and another involving a forward-propagating electroacoustic mode and a sideband daughter wave.

Authors:
;  [1];  [2];  [1];  [3]
  1. Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile)
  2. Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States)
  3. (Chile)
Publication Date:
OSTI Identifier:
22085995
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 19; Journal Issue: 8; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALFVEN WAVES; DISPERSION RELATIONS; ELECTROMAGNETIC RADIATION; ELECTRON TEMPERATURE; ELECTRON-POSITRON INTERACTIONS; FLUID MECHANICS; INSTABILITY; ION TEMPERATURE; MAGNETIC FIELDS; NONLINEAR PROBLEMS; RELATIVISTIC PLASMA; RELATIVISTIC RANGE

Citation Formats

Lopez, Rodrigo A., Munoz, Victor, Asenjo, Felipe A., Alejandro Valdivia, J., and Centro para el Desarrollo de la Nanociencia y la Nanotecnologia, CEDENNA, Santiago. Parametric decays in relativistic magnetized electron-positron plasmas with relativistic temperatures. United States: N. p., 2012. Web. doi:10.1063/1.4742315.
Lopez, Rodrigo A., Munoz, Victor, Asenjo, Felipe A., Alejandro Valdivia, J., & Centro para el Desarrollo de la Nanociencia y la Nanotecnologia, CEDENNA, Santiago. Parametric decays in relativistic magnetized electron-positron plasmas with relativistic temperatures. United States. doi:10.1063/1.4742315.
Lopez, Rodrigo A., Munoz, Victor, Asenjo, Felipe A., Alejandro Valdivia, J., and Centro para el Desarrollo de la Nanociencia y la Nanotecnologia, CEDENNA, Santiago. Wed . "Parametric decays in relativistic magnetized electron-positron plasmas with relativistic temperatures". United States. doi:10.1063/1.4742315.
@article{osti_22085995,
title = {Parametric decays in relativistic magnetized electron-positron plasmas with relativistic temperatures},
author = {Lopez, Rodrigo A. and Munoz, Victor and Asenjo, Felipe A. and Alejandro Valdivia, J. and Centro para el Desarrollo de la Nanociencia y la Nanotecnologia, CEDENNA, Santiago},
abstractNote = {The nonlinear evolution of a circularly polarized electromagnetic wave in an electron-positron plasma propagating along a constant background magnetic field is considered, by studying its parametric decays. Relativistic effects, of the particle motion in the wave field and of the plasma temperature, are included to obtain the dispersion relation of the decays. The exact dispersion relation of the pump wave has been previously calculated within the context of a relativistic fluid theory and presents two branches: an electromagnetic and an Alfven one. We investigate the parametric decays for the pump wave in these two branches, including the anomalous dispersion zone of the Alfven branch where the group velocity is negative. We solve the nonlinear dispersion relation for different pump wave amplitudes and plasma temperatures, finding various resonant and nonresonant wave couplings. We are able to identify these couplings and study their behavior as we modify the plasma parameters. Some of these couplings are suppressed for larger amplitudes or temperatures. We also find two kinds of modulational instabilities, one involving two sideband daughter waves and another involving a forward-propagating electroacoustic mode and a sideband daughter wave.},
doi = {10.1063/1.4742315},
journal = {Physics of Plasmas},
number = 8,
volume = 19,
place = {United States},
year = {Wed Aug 15 00:00:00 EDT 2012},
month = {Wed Aug 15 00:00:00 EDT 2012}
}
  • Parametric decays of a left-handed circularly polarized Alfvén wave propagating along a constant background magnetic field in a relativistic thermal electron-positron plasma are studied by means of a one dimensional relativistic particle-in-cell simulation. Relativistic effects are included in the Lorentz equation for the momentum of the particles and in their thermal motion, by considering a Maxwell-Jüttner velocity distribution function for the initial condition. In the linear stage of the simulation, we find many instabilities that match the predictions of relativistic fluid theory. In general, the growth rates of the instabilities increase as the pump wave amplitude is increased, and decreasemore » with a raise in the plasma temperatures. We have confirmed that for very high temperatures the Alfvén branch is suppressed, consistent with analytical calculations.« less
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  • We discuss the complete theory of spin-1/2 electron-positron quantum plasmas, when electrons and positrons move with velocities mach smaller than the speed of light. We derive a set of two fluid quantum hydrodynamic equations consisting of the continuity, Euler, spin (magnetic moment) evolution equations for each species. We explicitly include the Coulomb, spin-spin, Darwin and annihilation interactions. The annihilation interaction is the main topic of the paper. We consider the contribution of the annihilation interaction in the quantum hydrodynamic equations and in the spectrum of waves in magnetized electron-positron plasmas. We consider the propagation of waves parallel and perpendicular tomore » an external magnetic field. We also consider the oblique propagation of longitudinal waves. We derive the set of quantum kinetic equations for electron-positron plasmas with the Darwin and annihilation interactions. We apply the kinetic theory to the linear wave behavior in absence of external fields. We calculate the contribution of the Darwin and annihilation interactions in the Landau damping of the Langmuir waves. We should mention that the annihilation interaction does not change number of particles in the system. It does not related to annihilation itself, but it exists as a result of interaction of an electron-positron pair via conversion of the pair into virtual photon. A pair of the non-linear Schrodinger equations for the electron-positron plasmas including the Darwin and annihilation interactions is derived. Existence of the conserving helicity in electron-positron quantum plasmas of spinning particles with the Darwin and annihilation interactions is demonstrated. We show that the annihilation interaction plays an important role in the quantum electron-positron plasmas giving the contribution of the same magnitude as the spin-spin interaction.« less