Timescale for Radiation Belt Electron
Timescale for Radiation Belt Electron
复制标题
辐射带电子的时间表
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
R. R. Anderson
中科院分区：
文献类型：
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作者：
R. Horne;R. Thorne;S. Glauert;J. Albert;N. Meredith;R. R. Anderson
摘要：地球磁层内的电子加速需要解释在磁干扰期间MeV辐射带电子通量的增加。最近的研究表明，电子加速哨声模式合唱波成为最有效的外plasmapause，附近的L = 4.5，在电子相空间密度的峰值观察。我们目前的CRRES数据的空间分布的合唱团排放在活跃的条件。波的数据被用来计算俯仰角和能量扩散率在三个磁本地时间（MLT）部门，并获得一个时间尺度的加速。我们发现，合唱团的排放在中午前部门加速电子最有效地在纬度15度以上的赤道俯仰角在20度和60度之间。当电子在地球周围漂移时，它们被散射到大的俯仰角，并在赤道区域的夜面被合唱进一步加速。通过哨声模式合唱加速电子并将1 MeV的通量增加一个数量级的时间尺度约为1天，与风暴恢复阶段的卫星观测一致。在波加速过程中，电子经历许多漂移轨道，由此产生的俯仰角分布与能量有关。合唱散射应该产生平顶或蝴蝶形的俯仰角分布。结果为波浪加速度理论提供了有力的支持。
Abstract : Electron acceleration inside the Earth's magnetosphere is required to explain increases in the-MeV radiation belt electron flux during magnetically disturbed periods. Recent studies show that electron acceleration by whistler mode chorus waves becomes most efficient just outside the plasmapause, near L = 4.5, where peaks in the electron phase space density are observed. We present CRRES data on the spatial distribution of chorus emissions during active conditions. The wave data are used to calculate the pitch angle and energy diffusion rates in three magnetic local time (MLT) sectors and to obtain a timescale for acceleration. We show that chorus emissions in the prenoon sector accelerate electrons most efficiently at latitudes above 15 degrees for equatorial pitch angles between 20 degrees and 60 degrees. As electrons drift around the earth, they are scattered to large pitch angles and further accelerated by chorus on the nightside in the equatorial region. The timescale to accelerate electrons by whistler mode chorus and increase the flux at 1 MeV by an order of magnitude is approximately 1 day, in agreement with satellite observations during the recovery phase of storms During wave acceleration the electrons undergo many drift orbits and the resulting pitch angle distributions are energy-dependent. Chorus scattering should produce pitch angle distributions that are either flat-topped or butterfly-shaped. The results provide strong support for the wave acceleration theory.