Second-Harmonic Generation of Electromagnetic Emissions in a Magnetized Plasma: Kinetic Theory Approach
Second-Harmonic Generation of Electromagnetic Emissions in a Magnetized Plasma: Kinetic Theory Approach
复制标题
磁化等离子体中电磁发射的二次谐波产生：动力学理论方法
DOI：
10.1029/2020gl091762
复制
发表时间：
2021
影响因子：
5.2
通讯作者：
Xue Zuxiang
中科院分区：
文献类型：
--
作者：
Yu Xiongdong;Yuan Zhigang;Xue Zuxiang
在各种磁层波中观察到了二次谐波。尽管粒子模拟能够产生卫星观测中报告的类似特征，但产生二次谐波的确切物理机制仍未被发现。在这封信中，我们首先通过多尺度分析给出了描述基波和二次谐波的波动方程。然后，我们应用动力学理论的方法得到了磁化等离子体中的电导张量、非线性电流密度以及产生二次谐波的必要条件。为了验证我们的理论结果，我们还进行了混合模拟，研究了电磁离子回旋波的二次谐波产生的三种情况，其中二次谐波偏离固有模式的程度不同。我们的结果表明了线性色散关系在二次谐波产生中的重要作用。
Second harmonics have been observed in various magnetospheric waves. Although particle simulations are able to produce the similar features as reported in satellite observations, the exact physical mechanism for the generation of second harmonics remains uncovered yet. In this letter, we first give wave equations describing the fundamental and second harmonics via multiscale analysis. Then, we apply a kinetic theory approach to obtain the conductivity tensor, nonlinear current density, and the necessary conditions for the second harmonic generation of electromagnetic emissions in a magnetized plasma. To verify our theoretical results, we also perform hybrid simulations to study the second harmonic generation of electromagnetic ion cyclotron waves for three cases in which the second harmonic deviates from the inherent modes by different degrees. Our results suggest the important role of the linear dispersion relation in the second‐harmonic generation.