Low energy charged particle observations in the auroral magnetosphere: first results from the Akebono (EXOS-D) satellite
Low energy charged particle observations in the auroral magnetosphere: first results from the Akebono (EXOS-D) satellite
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极光磁层中的低能带电粒子观测：Akebono (EXOS-D) 卫星的第一个结果
DOI：
10.5636/jgg.42.479
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
T. Itoh
中科院分区：
文献类型：
--
作者：
T. Mukai;N. Kaya;E. Sagawa;M. Hirahara;W. Miyake;T. Obara;H. Miyaoka;S. Machida;H. Yamagishi;M. Ejiri;H. Matsumoto;T. Itoh
为了研究极光磁层中的粒子加速过程，日本Akebono(EXOS-D)卫星成功地进入了半极椭圆轨道。机载LEP(低能粒子)仪器可以进行三种不同类型的带电粒子观测：1)极光电子和离子的能量和俯仰角分布，2)正离子的每次电荷质量分析，以及3)在高频和甚低频范围内的粒子通量调制的机载探测。在本报告中，我们描述了LEP仪器，并介绍了上述项目1的一些初步结果。由于最初的轨道构型，重点放在日面现象上，包括极点。文中还给出了极帽中的高粒子活度和沿跨极弧热等离子体分布的独特例子。在尖点区的观测揭示了伴随着KeV范围离子的强烈但斑驳的电子通量，这些离子具有随时间/空间弥散的特征能量。这些数据被解释为磁鞘等离子体注入极尖的纵向和/或时间波动的特征。白天的特点是经常出现低能离子圆锥和束流，并伴随着强烈的低能电子沉淀。最后指出，沿磁力线向上移动的低能加速离子在跨极弧日边沿的一个非常有限的区域内被观测到。
The Japanese Akebono (EXOS-D) satellite was successfully put into a semipolar, elliptical orbit in order to study particle acceleration processes in the auroral magnetosphere. The onboard LEP (low energy particle) instrument makes three distinct types of charged particle observations: 1) energy and pitch-angle distributions of auroral electrons and ions, 2) mass per charge analysis of positive ions, and 3) onboard detection of particle flux modulations in the HF and VLF ranges. In this report we describe the LEP instrumentation, and present some preliminary results from item 1 above. Due to the initial orbital configuration, emphasis is placed on dayside phenomena, including the polar cusp. Unique examples of high particle activity in the polar cap and the hot plasma distribution along the transpolar arc are also presented. The observations in the cusp region reveal intense but patchy electron fluxes accompanied by keV-range ions with a characteristic energy versus time/space dispersion. The data are interpreted as signatures of longitudinal and/or temporal fluctuations of the magnetosheath plasma injection into the polar cusp. The dayside is characterized by the frequent appearance of low-energy ion conics and beams accompanied by intense low-energy electron precipitation. Finally it is noted that low-energy accelerated ions upgoing along the magnetic field line are observed in a very limited region around the dayside edge of the transpolar arc.