Sheared flows and small-scale Alfven wave generation in the auroral acceleration region
Sheared flows and small-scale Alfven wave generation in the auroral acceleration region
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DOI：
10.1029/2008gl036803
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发表时间：
2009-03-11
影响因子：
5.2
通讯作者：
Okada, M.
中科院分区：
文献类型：
--
作者：
Asamura, K.;Chaston, C. C.;Okada, M.
来自Reimei航天器的符合粒子和光学测量表明，通过倒V弧的剪切流可能对Alfven波的发射不稳定。粒子测量揭示了典型的低能电子由惯性阿尔芬波（IAWs）加速的时间分散场对准电子爆发。这些阿尔芬波加速电子嵌入在多keV的倒V电子结构。在倒V型结构的足迹的光学测量揭示了反向传播和折叠/涡旋离散极光形式，以类似于14-18公里/秒的速度移动。我们表明，从这个运动推断的流动剪切超过所需的不稳定性的阿尔芬波的发射尺度的顺序的电子惯性长度。这些波的发射为驱动我们观察到的低能分散电子爆发提供了一种可能的手段。引文：Asamura，K.，等人（2009年），极光加速区域中的切变流和小尺度阿尔芬波生成，Geophys.保留信函：36，L05105，doi：10.1029/2008GL036803。
Coincident particle and optical measurements from the Reimei spacecraft suggest that sheared flows through an inverted-V arc may be unstable to the emission of Alfven waves. The particle measurements reveal time dispersed field-aligned electron bursts typical of low energy electrons accelerated by inertial Alfven waves (IAWs). These Alfven wave accelerated electrons are embedded within multi-keV inverted-V electron structures. The optical measurements at the footprint of the inverted-V structures reveal counter propagating and folded/vortical discrete auroral forms moving with speeds of similar to 14-18 km/s. We show that the flow shear inferred from this motion exceeds that required for instability to the emission of Alfven waves on scales of the order of an electron inertial length. The emission of these waves provides a likely means for driving the low energy dispersed electron bursts we observe. Citation: Asamura, K., et al. (2009), Sheared flows and small-scale Alfven wave generation in the auroral acceleration region, Geophys. Res. Lett., 36, L05105, doi:10.1029/2008GL036803.