Particle‐in‐Cell Simulation of Rising‐Tone Magnetosonic Waves
Particle‐in‐Cell Simulation of Rising‐Tone Magnetosonic Waves
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DOI：
10.1029/2020gl089671
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发表时间：
2020-09
影响因子：
5.2
通讯作者：
Jicheng Sun;Lunjin Chen;Xueyi Wang;S. Boardsen;Yu Lin;Z. Xia
中科院分区：
文献类型：
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作者：
Jicheng Sun;Lunjin Chen;Xueyi Wang;S. Boardsen;Yu Lin;Z. Xia
最近的观测报告说，磁声波可以在频率-时间谱图中表现出升调结构。然而，其生成机制尚未确定。在本文中，我们使用一维粒子模拟（PIC）研究了在地球磁层中上升音磁声波的产生，其中等离子体由冷电子，冷质子和环分布质子组成。我们发现由环状分布质子激发的磁声波可以形成一个频率在0.5Ωlh到接近Ωlh范围内的升频结构，其中Ωlh是较低的混合频率。进一步证明了磁声波频率的上升可以用环形分布质子的散射来解释。此外，由PIC模拟得到的上升音时间尺度与卫星观测进行了比较。我们的发现为了解地球磁层等离子体波的非线性演化提供了一些新的见解。
Recent observations have reported that magnetosonic waves can exhibit rising‐tone structures in the frequency‐time spectrogram. However, the generation mechanism has not been identified yet. In this paper, we investigate the generation of rising‐tone magnetosonic waves in the terrestrial magnetosphere using 1‐D particle‐in‐cell (PIC) simulations, in which the plasma consists of three components: cool electrons, cool protons and ring distribution protons. We find that the magnetosonic waves excited by the ring distribution protons can form a rising‐tone structure with frequency of the structure ranging from about 0.5Ωlh to nearly Ωlh, where Ωlh is the lower hybrid frequency. It is further demonstrated that the rising frequency of magnetosonic waves can be accounted for by the scattering of ring distribution protons. Moreover, the rising‐tone timescale obtained by PIC simulation is compared with the satellite observation. Our findings provide some new insights to understand the nonlinear evolution of plasma waves in the Earth's magnetosphere.