年轻热流异常中回流离子的起源
Origin of the backstreaming ions in a young Hot Flow Anomaly
摘要：
我们分析了2006年2月22日星团探测器观测到的一个弓形激波前的事件。这一事件在发展的早期阶段具有热流异常的许多属性，包括强上游束和扰动的磁场剖面，如4个星团航天器所观察到的，一侧或两侧的磁场增加。电流片两侧的磁场矢量之间的夹角约为10°。HFA内的最小磁场大小约为1 nT。HFA两侧的激波是准垂直的。在HFA的前侧观察到上游光束。分别分析了C1和C3航天器上观测到的太阳风离子和上游离子的参数和速度分布，以跟踪它们在整个事件中的变化。该分析的目的是获得更多关于上游光束来源的信息。从观测开始到HFA相遇，光束的演化最初是高能的，几乎是单能的。随着HFA接近航天器，其平均能量不断降低，能谱不断加宽。第一次观察到的特定能量随着接近HFA而减少，随着离子的回旋半径而线性变化。积分束的能谱（所有观测）和在HFA前观测到的束的能谱与在HFA观测后约1小时弓形激波穿越后观测到的磁鞘离子能谱非常相似。仅在HFA内观察到束中的最低能量。上游束流的最高密度和压力出现在电流片本身。我们认为，上游束流是磁鞘离子通过与弓形激波阵面相交的HFA区域泄漏的结果。
英文摘要：
We analyze an event in front of the bow shock observed by Cluster spacecraft on 22.02.2006. This event has many attributes of Hot Flow Anomaly at early stage of development including strong upstream beam and disturbed magnetic profile with increased magnetic field at one or two sides as observed by 4 Cluster spacecraft. The angle between the magnetic field vectors at two sides of the current sheet was ~ 10°. The minimum magnetic field magnitude within HFA was ~ 1 nT. The shock at two sides of the HFA was quasi-perpendicular. Upstream beam was observed on the leading side of the HFA. Parameters and velocity distributions of solar wind ions and of upstream ions observed on C1 and C3 spacecraft are analyzed separately in order to trace their changes across the event. The goal of this analysis was to get more information about the source of upstream beam. The beam evolved from the start of its observation till the HFA encounter being initially energetic and nearly mono-energetic. Its mean energy continuously decreased and energy spectrum widened as HFA approached spacecraft. First observation of particular energy that diminished with approaching the HFA varied linearly with gyro-radius of ions. The energy spectra of integrated beam (for all observation) and the energy spectrum of the beam observed just in front of HFA are very similar to the magnetosheath ion energy spectrum observed after bow shock crossing at ~ 1 hour after observation of the HFA. Lowest energies in the beam were observed within HFA only. Highest density and pressure of upstream beam are found in the current sheet itself. We suggest that the upstream beam is the result of the magnetosheath ions leakage through the region of HFA crossing with the bow shock front.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
