Low‐charge‐state heavy ions upstream of Earth's bow shock and sunward flux of ionospheric O+1, N+1, and O+2 ions: Geotail observations
Low‐charge‐state heavy ions upstream of Earth's bow shock and sunward flux of ionospheric O+1, N+1, and O+2 ions: Geotail observations
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DOI：
10.1029/2000gl000039
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发表时间：
2000-08
影响因子：
5.2
通讯作者：
S. Christon;M. Desai;T. Eastman;G. Gloeckler;S. Kokubun;A. Lui;R. Mcentire;E. Roelof;D. Williams
中科院分区：
文献类型：
--
作者：
S. Christon;M. Desai;T. Eastman;G. Gloeckler;S. Kokubun;A. Lui;R. Mcentire;E. Roelof;D. Williams
1995-1998年，利用Geotail/STICS在数分钟到数小时的时间间隔内测量了高能~ 10-210 keV/e的低电荷态重离子（LCSHI）向地球弓激波方向（至X ~ 30 RE）。LCSHI通量在几十个间隔内是强而连续的，在此期间，电离层来源O+1、N+1和O+2的强成分在近径向的IMF上向太阳流动。但大多数情况下，只有“微量”水平存在。LCSHI通量是典型的，但不是唯一的，在漫射上游离子事件中观察到。在所示的四种情况中，有三种LCSHI伴随着向太阳方向的高能电子爆发，两次伴随着增强的货币基金组织波动。在最强的情况下，当O+1在航天器框架内向太阳流动时，H+、He+2、He+1和O+6的通量具有弱的各向异性，H+能谱是kappa - like。在扰动地磁条件下，最强的LCSHI通量往往出现在当地正午的黄昏。平均而言，LCSHI通量在日光侧的分布更为均匀。
Energetic ∼10–210 keV/e low‐charge‐state heavy ions (LCSHI) were measured sunward of Earth's bow shock (to X ∼ 30 RE) during numerous intervals lasting from minutes to hours using Geotail/STICS in 1995–1998. LCSHI fluxes are strong and continuous in a few tens of intervals, during which a strong component of ionospheric origin O+1, N+1, and O+2 streams sunward on nearly radial IMF. Most often though only ‘trace’ levels are present. LCSHI flux is typically, but not exclusively, observed during diffuse upstream ion events. LCSHI are accompanied by sunward energetic electron bursts in three of the four cases shown and twice by enhanced IMF fluctuations. As O+1 streams sunward in the spacecraft frame during the strongest case, H+, He+2, He+1, and O+6 fluxes have weak anisotropies and the H+ energy spectrum is kappa‐like. The strongest LCSHI fluxes tend to occur duskward of local noon during disturbed geomagnetic conditions. On average, LCSHI flux is more uniformly distributed across the dayside.