“嫦娥一号”卫星观测近月太阳风离子特征

摘要

“嫦娥一号”卫星的太阳风离子探测器(SWIDs)的科学目标是研究太阳风与月球的相互作用以及相应的近月空间等离子体环境.文章利用“嫦娥一号”卫星SWIDs探测器在2007年12月30日的观则数据对近月太阳风等离子体环境,包括向阳侧太阳风离子、“拾起”离子以及在月球尾迹边界处的太阳风离子的特征进行分析,得到以下主要观测结果:1)在慢速太阳风中观测到双峰结构,分别为太阳风中的氢离子和二价氦离子;2)在行星际磁场具有明显昏向(+Br)分量期间,在月球向阳侧持续观测到有月表散射或反射后被拾起的太阳风离子;3)与入射的太阳风离子不同,这些拾起的太阳风离子具有明显的角度分布特征;4)在行星际磁场昏向(晨向)期间,太阳风中的氢离子在月球尾迹北半球的边界处呈现减速(加速)特征并进入尾迹;而并未发现氦离子进入尾迹的特征.“嫦娥一号”卫星的这些观测数据对于认识近月空间等离子体环境有着重要的意义.%The solar wind ions detectors onboard the spacecraft Chang'E-1 (CE-1) have made a great contribution in advancing the understanding of the solar wind-Moon interaction and the induced near-Moon plasma environment.Several features of solar wind ions near the Moon were observed by the CE-1 on Dec 30,2007:1) both protons (H+) and alpha particles (He2+) were identified in the slow solar wind;2) the accelerated solar wind pickup ions were repeatedly observed on the lunar dayside under the nterplanetary magnetic field (IMF) By dominant conditions; 3) the accelerated pickup ions show being angle-dependent clearly and location-dependent sensitively; 4) under the IMF positive (negative) By conditions,the decelerated (accelerated) solar wind H+ intruded deep into the wake from the wake boundary in the northern hemisphere,while the He2+ population intruded less deep than H+.The revelation of these features may be of great help to understand the near-Moon plasma environment.