CLUSTER encounters with the high altitude cusp: boundary structure and magnetic field depletions
CLUSTER encounters with the high altitude cusp: boundary structure and magnetic field depletions
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DOI：
10.5194/angeo-22-1739-2004
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发表时间：
2004-04
影响因子：
1.9
通讯作者：
P. Cargill;M. Dunlop;B. Lavraud;R. Elphic;D. Holland;K. Nykyri;A. Balogh;I. Dandouras;H. Rème
中科院分区：
文献类型：
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作者：
P. Cargill;M. Dunlop;B. Lavraud;R. Elphic;D. Holland;K. Nykyri;A. Balogh;I. Dandouras;H. Rème
抽象的。本文介绍了2001年2月13日在一次高空尖点穿越期间四个航天器集群使命的数据。航天器配置有一个领先的航天器，与三个尾随航天器躺在一个平面，大致对应于名义磁层顶表面。典型的航天器间隔约为600公里。这次相遇发生在强大而稳定的南行星际磁场（IMF）的条件下。尖点被确定为磁场中的七分钟长的凹陷，与离子加热和高丰度的He+有关。尖点进入涉及通过磁层顶边界，该边界已经从其标称形状发生了非常显著的变形，正在快速移动，并且呈现出航天器分离量级或更小的尺度上的结构。该边界与磁场的旋转、法向场分量和进入尖点的约35 km/s的等离子体流有关。然而，它不能被确定为旋转不连续性。从尖点进入叶瓣的出口是通过一个最初很尖锐的边界，但随后以几公里/秒的速度向尾部撤退。当领先的航天器通过这个边界时，有一个约30 km/s的等离子体流从尖点流出，这表明这不是切向不连续。在离开尖点几分钟后，跟踪航天器的三个人在磁场中看到了一个类似尖点的信号。在三个尾随航天器中的两个航天器上有相关的温度升高。定时测量表明，这是由于尖点状区域脱离尖点边界的后部，并向尾部移动。尖点的磁场是高度无序的，四个航天器之间没有明显的关系，表明了尺度上的结构。磁层物理学（磁层顶、尖点和边界层;太阳风-磁层相互作用）-空间等离子体物理学（不连续性）
Abstract. Data from the four spacecraft Cluster mission during a high altitude cusp crossing on 13 February 2001 are presented. The spacecraft configuration has one leading spacecraft, with the three trailing spacecraft lying in a plane that corresponds roughly to the nominal magnetopause surface. The typical spacecraft separation is approximately 600km. The encounter occurs under conditions of strong and steady southward Interplanetary Magnetic Field (IMF). The cusp is identified as a seven-minute long depression in the magnetic field, associated with ion heating and a high abundance of He+. Cusp entry involves passage through a magnetopause boundary that has undergone very significant distortion from its nominal shape, is moving rapidly, and exhibits structure on scales of the order of the spacecraft separation or less. This boundary is associated with a rotation of the magnetic field, a normal field component, and a plasma flow into the cusp of approximately 35 km/s. However, it cannot be identified positively as a rotational discontinuity. Exit from the cusp into the lobe is through a boundary that is initially sharp, but then retreats tailward at a few km/s. As the leading spacecraft passes through this boundary, there is a plasma flow out of the cusp of approximately 30km/s, suggesting that this is not a tangential discontinuity. A few minutes after exit from the cusp, the three trailing the spacecraft see a single cusp-like signature in the magnetic field. There is an associated temperature increase at two of the three trailing spacecraft. Timing measurements indicate that this is due to cusp-like regions detaching from the rear of the cusp boundary, and moving tailward. The magnetic field in the cusp is highly disordered, with no obvious relation between the four spacecraft, indicative of structure on scales Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; solar wind-magnetosphere interactions) – Space plasma physics (discontinuities)