Finite gyroradius effects in the electron outflow of asymmetric magnetic reconnection

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• 作者：C. Norgren ; D. B. Graham ; Yu. V. Khotyaintsev ; M. André ; A. Vaivads ; L.‐J. Chen ; P.‐A. Lindqvist ; G. T. Marklund ; R. E. Ergun ; W. Magnes ; et al
• 刊名：Geophysical Research Letters
• 出版年：2016
• 出版时间：16 July 2016
• 年：2016
• 卷：43
• 期：13
• 页码：6724-6733
• 全文大小：1.5MB
• ISSN：1944-8007

文摘

We present observations of asymmetric magnetic reconnection showing evidence of electron demagnetization in the electron outflow. The observations were made at the magnetopause by the four Magnetospheric Multiscale (MMS) spacecraft, separated by ∼15 km. The reconnecting current sheet has negligible guide field, and all four spacecraft likely pass close to the electron diffusion region just south of the X line. In the electron outflow near the X line, all four spacecraft observe highly structured electron distributions in a region comparable to a few electron gyroradii. The distributions consist of a core with T_∥>T_⊥ and a nongyrotropic crescent perpendicular to the magnetic field. The crescents are associated with finite gyroradius effects of partly demagnetized electrons. These observations clearly demonstrate the manifestation of finite gyroradius effects in an electron-scale reconnection current sheet.