Energization of O+ ions in the Earth's inner magnetosphere and the effects on ring current buildup: A review of previous observations and possible mechanisms
Energization of O+ ions in the Earth's inner magnetosphere and the effects on ring current buildup: A review of previous observations and possible mechanisms
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DOI：
10.1002/jgra.50371
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发表时间：
2013-07-01
影响因子：
2.8
通讯作者：
Brandt, Pontus C.
中科院分区：
文献类型：
--
作者：
Keika, Kunihiro;Kistler, Lynn M.;Brandt, Pontus C.
现场观测和模拟工作已经证实，起源于地球电离层的单电荷氧离子O+在磁层中被加热/加速到> 100 keV。在磁暴期间，高能的O+对地球内磁层的等离子体压力有显著的贡献，尽管在安静的条件下，H+主导等离子体压力。压力的增强，我们称之为ESTA，是由绝热加热通过向地球输送的源人口的等离子体片，在内部磁层和近地等离子体片的局部加速，并从顶侧电离层的离子供应增强。关于O+比H+强的关键问题是非绝热局部加速，负责O+温度的增加，以及比H+更显著的O+供应，负责O+密度的增加。虽然已经提出了几种加速机制和O+供应过程，但什么机制/过程在更强的O+供应中起主导作用仍然是一个悬而未决的问题。本文综述了重要的航天器以前的观测，介绍了拟议的机制/过程，产生O+丰富的高能等离子体人口，并概述了可能的情况下，O+压力丰度在地球的内磁层。
In situ observations and modeling work have confirmed that singly charged oxygen ions, O+, which are of Earth's ionospheric origin, are heated/accelerated up to >100keV in the magnetosphere. The energetic O+ population makes a significant contribution to the plasma pressure in the Earth's inner magnetosphere during magnetic storms, although under quiet conditions, H+ dominates the plasma pressure. The pressure enhancements, which we term energization, are caused by adiabatic heating through earthward transport of source population in the plasma sheet, local acceleration in the inner magnetosphere and near-Earth plasma sheet, and enhanced ion supply from the topside ionosphere. The key issues regarding stronger O+ energization than H+ are nonadiabatic local acceleration, responsible for increase in O+ temperature, and more significant O+ supply than H+, responsible for the increase in O+ density. Although several acceleration mechanisms and O+ supply processes have been proposed, it remains an open question what mechanism(s)/process(es) play the dominant role in stronger O+ energization. This review paper summarizes important previous spacecraft observations, introduces the proposed mechanisms/processes that generate O+-rich energetic plasma population, and outlines possible scenarios of O+ pressure abundance in the Earth's inner magnetosphere.