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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >Comparison of TWINS images of low-altitude emission of energetic neutral atoms with DMSP precipitating ion fluxes
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Comparison of TWINS images of low-altitude emission of energetic neutral atoms with DMSP precipitating ion fluxes

机译：比较双胞胎低空的图像与DMSP发射的高能中性原子沉淀离子通量

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摘要

The brightest energetic neutral atom (ENA) intensity viewed by spacecraft in high-inclination Earth orbit is from low-altitude emission (LAE). It is a prominent feature in the stereo ENA images obtained by cameras on the NASA TWINS 1/2 Mission of Opportunity. This emission is produced by energetic magnetospheric ions precipitating into the atomic oxygen exosphere at latitudes near the auroral zones at altitudes ～300 km. The ions undergo multiple atomic collisions including charge exchange of ions and stripping of the resulting neutrals. Consequently, this is a "thick target" process. We introduce a "thick-target" approximation that allows us to extract the shape of the spatially averaged spectra of the precipitating ions from the ENA spectra in the TWINS 1/2 pixels viewing the LAE from near their orbital apogees. These ENA-extracted ion spectra are compared with in situ precipitating ion spectra measured concurrently by DMSP satellites (F15 and F16) at ～825 km altitude, while they are passing directly over the LAE regions in the TWINS 1/2 images. We obtain good agreement between the shape of the ENAextracted and in situ ion spectra from three distinct precipitation regions over energies from 2 to 32 keV (assuming precipitating protons). The absolute normalization of the ENA-extracted and in situ spectra depends upon the TWINS viewing geometry because the ENA LAE source is not resolved by the imager. None of the spectral shapes obtained is consistent with a simple thermal intensity spectrum with kT = 5 keV.
机译：最亮的高能中性原子(ENA)强度被飞船高倾角从低空地球轨道发射(莱城)。立体ENA在NASA得到摄像机的图像双胞胎1/2任务的机会。精力充沛的磁性层的离子产生的吗沉淀成原子氧外逸层高海拔地区的纬度极光区附近~ 300公里。包括离子的电荷交换碰撞剥离产生的中性色。因此,这是一个“厚目标”的过程。我们引入一个“厚靶”近似让我们来提取空间的形状平均沉淀离子的光谱双胞胎的ENA光谱1/2像素观看莱城附近的轨道远地点。ENA-extracted离子光谱相比原位沉淀离子光谱测量同时通过DMSP卫星(F15和F16)~ 825公里的高度,而他们是直接传递这对双胞胎在莱城地区1/2图像。获得良好的形状之间的协议从三个ENAextracted和原位离子光谱不同的降水区域能量从2 - 32 keV(假定沉淀质子)。绝对ENA-extracted和正常化原位光谱取决于双胞胎观看几何因为ENA莱城源不是解决成像仪。获得的形状与一个简单的一致热强度谱与kT = 5凯文。

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