Particle-in-cell Simulations of Particle Energization in the Auroral Region PDF Download

Author: Kaijun Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 394

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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781720522911
Category :
Languages : en
Pages : 74

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The discrete aurora results when energized electrons bombard the Earth's atmosphere at high latitudes. This paper examines the physical processes that can cause field-aligned acceleration of plasma particles in the auroral region. A data and theoretical study has been carried out to examine the acceleration mechanisms that operate in the auroral zone and to identity the magnetospheric drivers of these acceleration mechanisms. The observations used in the study were collected by the Fast Auroral SnapshoT (FAST) and Polar satellites when the two satellites were in approximate magnetic conjunction in the auroral region. During these events FAST was in the middle of the auroral zone and Polar was above the auroral zone in the near-Earth plasma sheet. Polar data was used to determine the conditions in the magnetotail at the time field-aligned acceleration was measured by FAST in the auroral zone. For each of the magnetotail drivers identified in the data study, the physics of field-aligned acceleration in the auroral region was examined using existing theoretical efforts and a long-system particle-in-cell simulation to model the magnetically connected region between the two satellites.Schriver, D. and Ashour-Abdalla, M. and Strangeway, R. J. and Richard, R. L. and Klezting, C. and Dotan, Y. and Wygant, J.Goddard Space Flight CenterAURORAL ZONES; POLAR REGIONS; ELECTRON ACCELERATION; PLASMA ACCELERATORS; ELECTRIC FIELDS; SATELLITE OBSERVATION; COMPUTERIZED SIMULATION; MAGNETOHYDRODYNAMIC WAVES

Author: Jaehong Park
Publisher:
ISBN:
Category :
Languages : en
Pages : 128

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"We focus on two important issues in collisionless astrophysical plasmas: (1) particle energization in collisionless low Mach number fast shocks in solar flares (Park et al. 2012,2013) and (2) energy transfer in two-temperature advection-dominated-accretion flows (Park et al. 2010). First, we study low Mach/high beta fast shocks which can occur above flare loop tops in the magnetic reconnection outflows of solar flares. These shocks may provide the electron energization responsible for the observed hard X-rays and contemporaneous radio emission. We present 2D particle-in-cell simulations of low Mach number/high beta shocks with quasi-perpendicular and perpendicular magnetic field orientations. Our results reveal shock-drift-acceleration (SDA) of electrons and ions in both the magnetic field orientations. More SDA-accelerated electrons are found in the quasi-perpendicular case compared to the perpendicular case. The transition energy between the thermal and non-thermal spectrum and the spectral index from the quasi-perpendicular shock simulations are consistent with some of the X-ray spectra from RHESSI in the energy regime of E [less than or approximately equal to] 40 ~ 100 keV. Plasma instabilities associated with the shock structure such as the modified-two-stream and the electron whistler instabilities are identified using numerical solutions of the kinetic dispersion relations. In low Mach number/high beta shocks, a modified two-stream instability due to the incoming and reflecting ions in the shock transition region acts as the mechanism to generate collisionless plasma turbulence that sustains the shock. We also show that the results from PIC simulations with reduced ion/electron mass ratio can be scaled to those with the realistic mass ratio. As the second part of this thesis, we study counter-streaming ion beam-driven instabilities using 1D and 2D particle-in-cell simulations to see whether a faster-than-Coulomb energy transfer mechanism exists in two-temperature advection dominated accretion flows. We numerically solve the 1D and 2D kinetic dispersion relations to analyze the PIC simulation results. We find that the interplay among these instabilities, the two-stream, oblique, and Weibel instabilities, in the 2D simulation can contribute to effective electron-ion energy coupling compared to the 1D simulations. We discuss the possibility of a faster-than-Coulomb energy transfer mechanism in two-temperature accretion flows"--Page viii-ix.

Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 924

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Author: D Bryant
Publisher: CRC Press
ISBN: 1482268531
Category : Science
Languages : en
Pages : 311

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How did electrons in the high atmosphere and space around the Earth come to acquire their speeds and energies? This intriguing question lies at the heart of understanding how high-energy electrons create the spectacular displays of the ^IAurora Borealis and ^IAurora Australis. Electron Acceleration in the Aurora and Beyond explores the mysteries

Author: Yam T. Chiu
Publisher:
ISBN:
Category : Auroras
Languages : en
Pages : 75

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The variation of the self-consistent electrostatic potential along the magnetic field is calculated by application of the principle of quasi-neutrality to the plasma components distributed along an auroral field line. The equilibrium plasma consists of hot anisotropic magnetospheric plasma, ionospheric plasma evaporated or extracted upwards by the parallel electrostatic field, and back scattered electrons. It is shown that the above charged-particle populations can support a potential difference of up to several kilovolts between the equator and the ionosphere along an auroral field line. Moreover, the corresponding parallel electric field has the proper signature to account for electron precipitation characteristics. Comparisons between theoretical and observed electron precipitation fluxes lead to estimates for the various physical parameters in the model. (Author).

Author: J. F. Fennell
Publisher:
ISBN:
Category :
Languages : en
Pages : 34

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Utilizing data from three satellites the document presents the relationship between the particle energy and angular distributions, the resulting auroral forms, and spatial features such as the inverted V and electrostatic structures. The occurrence of field-aligned electrons over a wide range of energies near and at the edges of inverted V structures in the low altitude local evening auroral region is an outstanding feature in the data. The DMSP pictures often show a brightening of the auroral form in coincidence with similar intense electron precipitation at the edges of inverted V structures. Preliminary examination of the S3-3 data has produced only a few such events with a tendency for them to occur at lower altitudes. As a separate topic, a detailed description of a high altitude inverted V structure is presented using S3-3 data. The region contained strong perpendicular electric field structures embedded therein. The potential drop in the region peaks near 16 kV with 10-12 kV below and 4-6 kV above 8000 km. The modification of the electron distributions due to strong electric field structures is analyzed. The signature of the acceleration in the electrons is consistent with an acceleration region that starts 2000-4000 km above the satellite altitude of 8000 km and extends well below the satellite. (Author).

Author: Yukitoshi Nishimura
Publisher: Elsevier
ISBN: 0128213736
Category : Science
Languages : en
Pages : 566

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Cross-Scale Coupling and Energy Transfer in the Magnetosphere-Ionosphere-Thermosphere System provides a systematic understanding of Magnetosphere-Ionosphere-Thermosphere dynamics. Cross-scale coupling has become increasingly important in the Space Physics community. Although large-scale processes can specify the averaged state of the system reasonably well, they cannot accurately describe localized and rapidly varying structures in space in actual events. Such localized and variable structures can be as intense as the large-scale features. This book covers observations on quantifying coupling and energetics and simulation on evaluating impacts of cross-scale processes. It includes an in-depth review and summary of the current status of multi-scale coupling processes, fundamental physics, and concise illustrations and plots that are usable in tutorial presentations and classrooms. Organized by physical quantities in the system, Cross-Scale Coupling and Energy Transfer in the Magnetosphere-Ionosphere-Thermosphere System reviews recent advances in cross-scale coupling and energy transfer processes, making it an important resource for space physicists and researchers working on the magnetosphere, ionosphere, and thermosphere. Describes frontier science and major science around M-I-T coupling, allowing for foundational understanding of this emerging field in space physics Reviews recent and key findings in the cutting-edge of the science Discusses open questions and pathways for understanding how the field is evolving

Author: Mioara Mandea
Publisher: Cambridge University Press
ISBN: 1108418481
Category : Science
Languages : en
Pages : 347

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An interdisciplinary review of research in geomagnetism, aeronomy and space weather, written by eminent researchers from these fields.

Author: David J. Gorney
Publisher:
ISBN:
Category : Auroras
Languages : en
Pages : 32

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In the 1970's major advances in the understanding of auroral processes were brought about by observations of plasmas and electric fields within the regions of space responsible for auroral particle acceleration. The major contribution of these observations was the verification of the existence of electric fields with components parallel to the magnetic field over large regions of altitude (1000-20000 kilometers). These electric fields constitute potential drops of several kilovolts, accelerating magnetospheric electrons downward to form the aurora and ionospheric ions upward, where they contribute significantly to the magnetospheric hot ion population. Perpendicular spatial scales of about 100 kilometers are most common, although finer scales have been observed embedded, and individual small amplitude double layers occur on much smaller parallel spatial scales. More recently, the same data sets have revealed the existence of about 100 V electric potential drops directed downward in return current regions. Downward electric fields are in a direction to accelerate electrons out of the ionsphere and tend to retard the propagation of ions upward. An association between upflowing electron beams and transversely heated ions at low altitude has been noted, and a casual relationship between downward electric fields and ion conics is suggested.