Multi-spacecraft observations of small-scale fluctuations in density and fields in plasmaspheric plumes
Multi-spacecraft observations of small-scale fluctuations in density and fields in plasmaspheric plumes
复制标题
多航天器观测等离子体层羽流密度和场的小尺度波动
DOI：
10.5194/angeo-30-623-2012
复制
发表时间：
2012
影响因子：
1.9
通讯作者：
R. Torbert
中科院分区：
文献类型：
--
作者：
H. Matsui;F. Darrouzet;J. Goldstein;P. Puhl;Y. Khotyaintsev;P. Lindqvist;E. Georgescu;C. Mouikis;R. Torbert
抽象的。在这一事件的研究中，等离子体层羽流的小尺度波动的时间尺度为10秒到分钟的航天器帧进行检查。在一个事件中，等离子体层羽流被Cluster观测到，而IMAGE在类似的位置测量到密度增强。星团探测到的羽流中存在密度波动，并伴随着磁场和电场的波动。磁波动是横向的，并且沿着羽流的方向。E / B比小于阿尔芬速度。另一个类似的事件是简要介绍。然后我们考虑波动的物理性质。反馈不稳定性调制的阿尔文模式是一种可能性，虽然非本地生成是可能的。很难证明波动代表一种快速模式。互换运动是可能的，由于测量和期望之间的一致性。能量来源可能是等离子体层羽流中的压力或密度梯度。当更多的事件积累起来，统计分析变得可行时，这种类型的研究将有助于了解羽流的时间演变。
Abstract. In this event study, small-scale fluctuations in plasmaspheric plumes with time scales of ~10 s to minutes in the spacecraft frame are examined. In one event, plasmaspheric plumes are observed by Cluster, while IMAGE measured density enhancement at a similar location. Fluctuations in density exist in plumes as detected by Cluster and are accompanied by fluctuations in magnetic fields and electric fields. Magnetic fluctuations are transverse and along the direction of the plumes. The E / B ratio is smaller than the Alfven velocity. Another similar event is briefly presented. We then consider physical properties of the fluctuations. Alfven mode modulated by the feedback instability is one possibility, although non-local generation is likely. It is hard to show that the fluctuations represent a fast mode. Interchange motion is possible due to the consistency between measurements and expectations. The energy source could be a pressure or density gradient in plasmaspheric plumes. When more events are accumulated so that statistical analysis becomes feasible, this type of study will be useful to understand the time evolution of plumes.