Energetic electron acceleration in the downstream reconnection outflow region
Energetic electron acceleration in the downstream reconnection outflow region
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DOI：
10.1029/2006ja011847
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发表时间：
2007-03
影响因子：
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通讯作者：
S. Imada;R. Nakamura;P. Daly;M. Hoshino;Wolfgang Baumjohann;S. Mühlbachler;A. Balogh;H. Rème
中科院分区：
文献类型：
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作者：
S. Imada;R. Nakamura;P. Daly;M. Hoshino;Wolfgang Baumjohann;S. Mühlbachler;A. Balogh;H. Rème
[1]利用自适应粒子成像探测器（Cluster/Research with Adaptive Particle Imaging Detectors）观测了向地重联流出区的高能电子。我们发现了一个很好的相关性之间的高能电子增强和正常的磁场（BZ）增强在0.25秒的时间分辨率。大的正常磁场被认为与磁场重联有关，因为在快速质子尾向/向地流反转期间观察到的负/正Bz反转是磁场重联的良好指示。利用四航天器星团，我们可以清楚地看到，这个大的正Bz结构是向地球方向传播的。此外，我们还发现高能电子的能谱向下游区域变硬。还观察到负Bz增强。与负Bz增强相关联的高能电子增强的强度比与正Bz增强相关联的弱。为了讨论磁场重联区高能电子加速的时空分布，我们确定了航天器在磁场重联随时间变化结构中的位置。我们的观察清楚地表明，第二步加速，除了X线加速，在下游重联流出区域的高能电子。
[1] Energetic electrons in an earthward reconnection outflow region have been observed by Cluster/Research with Adaptive Particle Imaging Detectors. We found a good correlation between the energetic electron enhancement and a normal magnetic field (Bz) enhancement within a 0.25-s time resolution. The large normal magnetic field is thought to be associated with magnetic reconnection because the negative/positive Bz reversal observed during the fast proton tailward/earthward flow reversal is a good indicator of magnetic reconnection. Using the four-spacecraft Cluster, we can clearly see that this large positive Bz structure propagates in the earthward direction. Furthermore, we find that the energy spectrum of the energetic electrons becomes harder toward the downstream region. A negative Bz enhancement is also observed. The intensity of energetic electron enhancement associated with the negative Bz enhancement is weaker than that associated with the positive one. To discuss the temporal and spatial profile of energetic electron acceleration in the magnetic reconnection region, we determined the spacecraft position in the temporally evolving magnetic structures of reconnection. Our observation clearly indicates second-step acceleration, in addition to X line acceleration, of energetic electrons in the downstream reconnection outflow region.