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Record Details

Record 25 of 152
Simulation Study of Magnetic Fields generated by the Electromagnetic Filamentation Instability driven by Pair Loading
Author and Affiliation:
Nishikawa, K.-I.(National Space Science and Technology Center, Huntsville, AL, United States)
Ramirez-Ruiz, E.(California Univ., Santa Cruz, CA, United States)
Hededal, C.(Niels Bohr Inst., Dept. of Astrophysics, Copenhagen, Denmark)
Hardee, P.(Alabama Univ., Tuscaloosa, AL, United States)
Mizuno, Y.(NASA Marshall Space Flight Center, Huntsville, AL, United States)
Fishman, G. J.(NASA Marshall Space Flight Center, Huntsville, AL, United States)
Abstract: Using a 3-D relativistic particle-in-cell (RPIC) code, we have investigated particle acceleration associated with a relativistic electron-positron (cold) jet propagating into ambient electron-positron and electron-ion plasmas without initial magnetic fields in order to investigate the nonlinear stage of the Weibel instability. We have also performed simulations with broad Lorentz factor distribution of jet electrons and positrons, which are assumed to be created by the photon annihilation. The growth time and nonlinear saturation levels depend on the initial jet parallel velocity distributions and ambient plasma. Simulations show that the Weibel instability created in the collisionless shocks accelerates jet and ambient particles both perpendicular and parallel to the jet propagation direction. The nonlinear fluctuation amplitude of densities, currents, electric, and magnetic fields in the electron-ion ambient plasma are larger than those in the electron-positron ambient plasma. We have shown that plasma instabilities driven by these streaming electron-positron pairs are responsible for the excitation of near-equipartition, turbulent magnetic fields. These fields maintain a strong saturated level on timescales much longer than the electron skin depth at least for the duration of the simulations. Our results reveal the importance of the electromagnetic filamentation instability in ensuring an effective coupling between electron-positron pairs and ions, and may help explain the origin of large upstream fields in GRB shock.
Publication Date: Jan 01, 2007
Document ID:
20070018776
(Acquired Jun 04, 2007)
Subject Category: ASTROPHYSICS
Document Type: Conference Paper
Meeting Information: THe Next Decade of Gamma-ray Bursts Afterglows; 19-23 Mar. 2007; Amsterdam; Netherlands
Financial Sponsor: NASA Marshall Space Flight Center; Huntsville, AL, United States
Organization Source: NASA Marshall Space Flight Center; Huntsville, AL, United States
Description: 1p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: PARTICLE ACCELERATION; ELECTRON-POSITRON PAIRS; MAGNETIC FIELDS; MAGNETOHYDRODYNAMIC STABILITY; RELATIVISTIC PARTICLES; PLASMA JETS; WEIBEL INSTABILITY; TURBULENCE
Availability Source: Other Sources
Availability Notes: Abstract Only
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