Acceleration of Electrons by Whistler-Mode Hiss Waves at Saturn.
Acceleration of Electrons by Whistler-Mode Hiss Waves at Saturn.
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DOI：
10.1029/2021gl096213
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发表时间：
2022-02-16
影响因子：
5.2
通讯作者：
Shprits, Y. Y.
中科院分区：
文献类型：
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作者：
Woodfield, E. E.;Glauert, S. A.;Menietti, J. D.;Horne, R. B.;Kavanagh, A. J.;Shprits, Y. Y.
众所周知，地球上的等离子体层嘶嘶波通过波粒相互作用造成辐射带的电子损失。然而，在土星，我们发现不同的等离子体密度环境导致电子的加速，而不是损失。等离子体频率与电子回转频率的比率经常降到1以下，这为HISS加速电子创造了条件。HISS在高纬度(>；25°)的位置与这个密度极低的区域非常吻合。电子和嘶鸣之间的相互作用只发生在这些高纬度，因此加速被限制在中到低俯仰角导致蝴蝶俯仰角分布。嘶嘶声通常比土星上的合唱强一个数量级，由此产生的加速度很快，在L=7.7时，在0.4 MeV的一天内接近稳定状态，并且随着L壳层的增加，这种影响更强。低等离子体/陀螺频率比引起哨声加速而不是散射电子，在高纬度加速可能导致蝶形电子俯仰角分布在小时尺度上的快速加速随着L壳层的增加而增强
Plasmaspheric hiss waves at the Earth are well known for causing losses of electrons from the radiation belts through wave particle interactions. At Saturn, however, we show that the different plasma density environment leads to acceleration of the electrons rather than loss. The ratio of plasma frequency to electron gyrofrequency frequently falls below one creating conditions for hiss to accelerate electrons. The location of hiss at high latitudes (>25°) coincides very well with this region of very low density. The interaction between electrons and hiss only occurs at these higher latitudes, therefore the acceleration is limited to mid to low pitch angles leading to butterfly pitch angle distributions. The hiss is typically an order of magnitude stronger than chorus at Saturn and the resulting acceleration is rapid, approaching steady state in one day at 0.4 MeV at L = 7 and the effect is stronger with increasing L‐shell. Low ratio of plasma to gyro‐frequency causes whistler‐mode hiss to accelerate rather than scatter electrons Hiss acceleration at high latitudes may lead to butterfly electron pitch angle distributions Rapid acceleration over a timescale of hours which strengthens with increasing L‐shell