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Electron and Ion Acceleration Associ...

Liang, Haoming.

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Electron and Ion Acceleration Associated with Magnetotail Reconnection.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Electron and Ion Acceleration Associated with Magnetotail Reconnection./
作者:	Liang, Haoming.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2017,
面頁冊數:	235 p.
附註:	Source: Dissertation Abstracts International, Volume: 78-08(E), Section: B.
Contained By:	Dissertation Abstracts International78-08B(E).
標題:	Plasma physics. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10262885
ISBN:	9781369670738

Electron and Ion Acceleration Associated with Magnetotail Reconnection.
Liang, Haoming.

Electron and Ion Acceleration Associated with Magnetotail Reconnection. - Ann Arbor : ProQuest Dissertations & Theses, 2017 - 235 p.

Source: Dissertation Abstracts International, Volume: 78-08(E), Section: B.

Thesis (Ph.D.)--University of California, Los Angeles, 2017.

This dissertation is dedicated to understanding electron and ion acceleration associated with magnetotail reconnection during substorms by using numerical simulations. Electron dynamics were investigated by using the UCLA global magnetohydrodynamic (MHD) model and large scale kinetic (LSK) simulations. The neutral line configurations and magnetotail flows modify the amounts of the adiabatic and non-adiabatic acceleration that electrons undergo. This causes marked differences in the temperature anisotropy for different substorms. In particular, one substorm event analyzed shows T&perp; > T&par; (T&perp; / T &par; ≈ 2.3)at ~-10RE while another shows T &par; > T&perp; (T &perp; / T&par; ≈ 0.8), where T&perp; and T&par; (second order moments of the distribution functions) are defined with respect to the magnetic field. These differences determine the subsequent acceleration of the energetic electrons in the inner magnetosphere. Whether the acceleration is mostly parallel or perpendicular is determined by the location of dayside reconnection.

ISBN: 9781369670738Subjects--Topical Terms:

3175417
Plasma physics.

Electron and Ion Acceleration Associated with Magnetotail Reconnection.
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245 1 0 $a Electron and Ion Acceleration Associated with Magnetotail Reconnection.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2017
300 $a 235 p.
500 $a Source: Dissertation Abstracts International, Volume: 78-08(E), Section: B.
500 $a Adviser: George Morales.
502 $a Thesis (Ph.D.)--University of California, Los Angeles, 2017.
520 $a This dissertation is dedicated to understanding electron and ion acceleration associated with magnetotail reconnection during substorms by using numerical simulations. Electron dynamics were investigated by using the UCLA global magnetohydrodynamic (MHD) model and large scale kinetic (LSK) simulations. The neutral line configurations and magnetotail flows modify the amounts of the adiabatic and non-adiabatic acceleration that electrons undergo. This causes marked differences in the temperature anisotropy for different substorms. In particular, one substorm event analyzed shows T&perp; > T&par; (T&perp; / T &par; ≈ 2.3)at ~-10RE while another shows T &par; > T&perp; (T &perp; / T&par; ≈ 0.8), where T&perp; and T&par; (second order moments of the distribution functions) are defined with respect to the magnetic field. These differences determine the subsequent acceleration of the energetic electrons in the inner magnetosphere. Whether the acceleration is mostly parallel or perpendicular is determined by the location of dayside reconnection.
520 $a A 2.5D implicit Particle-in-Cell simulation was used to study the effects produced by oxygen ions on magnetotail reconnection, and the associated acceleration of protons and oxygen ions. The inertia of oxygen ions reduces the reconnection rate and slows down the earthward propagation of dipolarization fronts (DFs). An ambipolar electric field in the oxygen diffusion region contributes to the smaller reconnection rate. This change in the reconnection rate affects the ion acceleration. In particular 67% of protons and 58% of oxygen ions were accelerated in the exhaust (between the X-point and the DF) in a simulation corresponding to a magnetic storm in which there was a 50% concentration of oxygen ions. In addition, 42% of lobe oxygen-ions are accelerated locally by the Hall electric field, far away from the X-point without entering the exhaust. Protons at the same locations experience Ex B drift. This finding extends previous knowledge that oxygen and proton acceleration associated with reconnection mainly occurs in the exhaust and is consistent with Cluster observations. Oxygen ions and protons in the pre-existing current sheet are reflected by the DFs. The reflected oxygen beam forms a hook-shaped signature in phase space. In principle, this signature can be applied to deduce the DF speed history, and thus lead to remote-sensing of the reconnection dynamics.
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