Computer simulation of chorus wave generation in the Earth's inner magnetosphere
Computer simulation of chorus wave generation in the Earth's inner magnetosphere
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DOI：
10.1029/2006gl028594
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发表时间：
2007-02-03
影响因子：
5.2
通讯作者：
Omura, Yoshiharu
中科院分区：
文献类型：
--
作者：
Katoh, Yuto;Omura, Yoshiharu
用偶极磁场模型进行了自洽粒子模拟，成功地再现了具有上升音调的合唱发射。我们假设高能电子在赤道区形成高度各向异性的速度分布。除了高能电子引起的电磁热噪声外，不假定有初始波。在模拟的早期阶段，通过高能电子的温度各向异性驱动的不稳定性，从赤道产生相干哨声模波。在哨模波的传播过程中，我们发现在模拟系统的频谱空间分布中形成了具有负频率梯度的窄带发射(NEWNFG)。NEWNFG的后缘是在赤道附近区域以不断增加的频率不断产生的。在定点观察，NEWNFG显示出典型的合唱发射的频率变化。
A self-consistent particle simulation with a dipole magnetic field model is carried out, reproducing chorus emissions with rising tones successfully. We assume energetic electrons forming a highly anisotropic velocity distribution in the equatorial region. No initial wave is assumed except for electromagnetic thermal noise induced by the energetic electrons. In the early stage of the simulation, coherent whistler-mode waves are generated from the equator through an instability driven by the temperature anisotropy of the energetic electrons. During the propagation of the whistler-mode waves, we find formation of a narrowband emission with negative frequency gradient (NEWNFG) in the spatial distribution of the frequency spectrum in the simulation system. The trailing edge of NEWNFG is continuously created at increasing frequencies in the region close to the equator. Observed at a fixed point, the NEWNFG shows a frequency variation of a typical chorus emission.