Effect of upflowing field-aligned electron beams on the electron cyclotron waves in the auroral magnetosphere
Effect of upflowing field-aligned electron beams on the electron cyclotron waves in the auroral magnetosphere
复制标题
上流场对准电子束对极光磁层中电子回旋波的影响
DOI：
10.1007/s12043-007-0063-z
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
A. Gwal
中科院分区：
文献类型：
--
作者：
Sushi I Kumar;S. Singh;A. Gwal
本文分析了低密度上升流场向电子束（FEBs）在等离子体频率ωe/Ωe < 1的极光区对沿地磁场方向向下传播的频率为ωr < Ωe的电子回旋波增长率的影响。具有低到高能量（E B）但具有低温度（T_b B）的FEB对这些波没有影响。发现E B < 1 keV和T_（B）> 1.5 keV的FEB对生长速率有显著影响。分析表明，主要是T_b B抑制了高频谱中不稳定性的增长率（幅度）和频率范围（带宽）。随着T_（B）的增加，对生长速率和带宽的抑制作用增强。具有较小Eb（给定漂移速度）的FEBs比具有较大Eb的梁降低更多的生长速率。生长速率的抑制随ωe/Ωe的增加而增加，表明在较高的海拔高度，光束更有效。
The role of low density upflowing field-aligned electron beams (FEBs) on the growth rate of the electron cyclotron waves at the frequencies ωr < Ωe, propagating downward in the direction of the Earth’s magnetic field, has been analysed in the auroral region at ωe/Ωe < 1 where ωe is the plasma frequency and Ωe is the gyrofrequency. The FEBs with low to high energy (Eb) but with low temperature (T‖b) have no effect on these waves. The FEBs with Eb < 1 keV and T‖b (> 1.5 keV) have been found to have significant effect on the growth rate. Analysis has revealed that it is mainly the T‖b which inhibits the growth rate (magnitude) and the range of frequency (bandwidth) of the instability mainly in the higher frequency spectrum. The inhibition in the growth rate and bandwidth increases with increase in T‖b. The FEBs with less Eb (giving drift velocity) reduce growth rate more than the beams with larger Eb. The inhibition of growth rate increases with the increase in the ratio ωe/Ωe indicating that the beams are more effective at higher altitudes.