Fundamental technical development of the detector system of the solar resonance scattering light by analyzing the ion density and velocity distribution

我们研究了对存在于地球磁尾中的氧离子成像的可能性。由于我们直到几年前才知道地球磁层尾部区域存在氧离子，搜索磁层的GEOTAIL航天器发现了温度极低、密度很高的氧离子。这些氧离子以光束的形式从地球流向尾巴方向，距离越远，速度越快。如果我们能利用氧离子拍摄整个磁层，我们将在研究磁层动力学方面取得重大进展。当氧离子相对于太阳运动时，共振散射光的波长受到多普勒频移的影响。当离子发生多普勒频移时，谐振散射线的宽度为几十毫埃，而太阳光的发射线宽度与之相当，使得谐振散射效率变差。当相对速度超过50km/s时，共振散射基本上不会发生在氦的单一发射线上。另一方面，氧离子，有三条共振散射线，它们彼此非常接近。太阳光中有9条与氧离子（单电离和双电离）相对应的发射谱线，因此氧离子受到相对运动的多普勒频移时，可以共振地散射另一条发射谱线。考虑到这种影响，我们计算了反映共振散射效率的几何因子。同时，利用GEOTAIL卫星测得的氧离子速度、温度和密度模型，模拟了磁层尾部区域的氧离子散射光强度。利用这些值，我们得出光的强度为0.1-10瑞利。这意味着我们可以使用直径为25厘米的望远镜，以1 Re（地球半径）的分辨率对地球磁层进行成像，曝光时间约为10分钟。因此，我们的研究表明，磁尾成像在原则上是可能的。少

We studied the possibility to image the oxygen ions which exist in the Earth's magnetotail. As we had had no knowledge of the existence of the oxygen ions in the tail region of the Earth's magnetosphere until several years before, the GEOTAIL spacecraft, which serches for the magnetosphere, identified the oxygen ions with very low temperature and high density. These oxygen ions flow as a beam from the Earth to the tail direction, whose velocity becomes higher as more distant. We will make big progress in studying the dynamics of the magnetosphere, if we can take picutres of the whole magnetosphere by using oxygen ions. The wavelength of the resonant scattering light is subject to the Doppler shifting, as the oxygen ions move relatively to the Sun. The efficiency of the resonant scatter becomes worse when ions are largely Doppler shifted because the width of the resonant scattering lines is several tens of milli-angstrom and the emission line width of the sun light is the same order to … More this. Resonant scatter does not occur essentially to the single emission line as helium, when relative velocity becomes over 50km/sec. Oxygen ions, on the other hand, have three resonant scattering lines which are very close to each other. There are 9 emission lines corresponding to the (singly and doubly ionized) oxygen ion in the solar light, so Oxygen ions can scatter another emission line resonantly when they are subjected to the Doppler shifting by the relative motion. We calculated the geometric factor which show the efficiency of the resonant scatter considering this effect. Also, we simulated the intensity of the scattered light from the tail region of the magnetosphere by the oxygen ions by using the model of the velocity, temperature and density of the oxygen ions from the results of the GEOTAIL spacecraft. Using these values, we concluded that the intensity of the light is 0.1-10 Rayleigh. The result means that we can image the Earth's magnetosphere with the resolution of 1 Re (Earth's radius) by using 25 cm diameter telescope, exposing about 10 minutes. Thus our study show the imaging of the magnetotail is possible in principle. Less