Distribution function of precipitating ion beams with velocity dispersion observed near the poleward edge of the nightside auroral oval
Distribution function of precipitating ion beams with velocity dispersion observed near the poleward edge of the nightside auroral oval
复制标题
夜侧极光椭圆形极向边缘附近观察到的速度色散沉淀离子束的分布函数
DOI：
10.1029/92gl02500
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发表时间：
1992
影响因子：
5.2
通讯作者：
N. Kaya
中科院分区：
文献类型：
--
作者：
Y. Saito;T. Mukai;M. Hirahara;S. Machida;N. Kaya
利用Akebono卫星获得的低能离子数据，计算了极光电子沉淀区极缘观测到的速度分散离子束的分布函数。计算得到的分布函数可以很好地用体积能为几keV、温度为几百eV的一维位移麦克斯韦方程拟合。体积能与温度呈正相关，这可能表明当离子加速到更高的能量时，它们同时被加热到更高的温度。我们还发现了观测到的离子束的不变纬度宽度除以温度的平方根与其体速度之间的关系，这表明离子束的源区是致密的。这些离子束的出现概率很高，这表明它们是由地球磁尾中的一条稳定的x型中性线提供的。
Using low energy ion data obtained by Akebono satellite, we have calculated distribution functions of velocity-dispersed ion beams observed at the poleward edge of the auroral electron precipitation region. The calculated distribution functions can well be fitted by one-dimensional shifted-Maxwellians, whose bulk energy and temperature are several keV and several hundreds of eV, respectively. The bulk energy and temperature show a positive correlation, which may indicate that when the ions are accelerated to higher energy, they are heated to higher temperature simultaneously. We have also found a relation between the invariant latitude width of the observed ion beams divided by the square root of the temperature and their bulk velocity, which indicates that the source region of the ion beam is compact. These ion beams are obtained with high occurrence probability, suggesting that they are supplied from a steady X-type neutral line in the earth's magnetotail.