Tracing solar wind plasma entry into the magnetosphere using ion‐to‐electron temperature ratio
Tracing solar wind plasma entry into the magnetosphere using ion‐to‐electron temperature ratio
复制标题
使用离子电子温度比追踪太阳风等离子体进入磁层
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
Jim Wild
中科院分区：
文献类型：
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作者：
B. Lavraud;J. Borovsky;V. Génot;Steven J. Schwartz;J. Birn;A. Fazakerley;M. Dunlop;Matthew Taylor;H. Hasegawa;A. Rouillard;J. Berchem;Y. Bogdanova;D. Constantinescu;I. Dandouras;J. Eastwood;C. Escoubet;Harald U. Frey;C. Jacquey;E. Panov;Zuyin Pu;Chao Shen;Junru Shi;D. Sibeck;M. Volwerk;Jim Wild
当太阳风马赫数较低时，通常例如在磁云中，弓形激波的物理学导致下游离子与电子的温度比可以明显低于平常。我们利用这一属性跟踪太阳风等离子体进入磁层使用集群测量在附近的黄昏磁层顶在2001年11月25日在地球上的磁云的通道。磁鞘中的离子-电子温度比确实很低（Ti/Te = 3）。在这一天，总共遇到了三个磁层顶边界层间隔。它们都表明，当等离子体进入磁层时，低的离子-电子温度比可以保持，无论是否观察到开尔文-亥姆霍兹活动。这表明磁层顶边界层中的离子-电子温度比通常很高，并不是由形成这些边界层的等离子体进入机制的加热特性所规定的。在未来，这一特性可用于（1）进一步跟踪等离子体进入内部区域，（2）确定首选的进入机制，如果其他理论，观测和模拟工作可以给出指示，哪些机制可能会改变这一比例。
When the solar wind Mach number is low, typically such as in magnetic clouds, the physics of the bow shock leads to a downstream ion‐to‐electron temperature ratio that can be notably lower than usual. We utilize this property to trace solar wind plasma entry into the magnetosphere by use of Cluster measurements in the vicinity of the dusk magnetopause during the passage of a magnetic cloud at Earth on November 25, 2001. The ion‐to‐electron temperature ratio was indeed low in the magnetosheath (Ti/Te ∼ 3). In total, three magnetopause boundary layer intervals are encountered on that day. They all show that the low ion‐to‐electron temperature ratio can be preserved as the plasma enters the magnetosphere, and both with and without the observation of Kelvin‐Helmholtz activity. This suggests that the ion‐to‐electron temperature ratio in the magnetopause boundary layer, which is usually high, is not prescribed by the heating characteristics of the plasma entry mechanism that formed these boundary layers. In the future, this property may be used to (1) further trace plasma entry into inner regions and (2) determine the preferred entry mechanisms if other theoretical, observational and simulation works can give indications on which mechanisms may alter this ratio.