Dokgo Kyunghwan, Hwang Kyoung-Joo, Burch James L, Choi Eunjin, Yoon Peter H, Sibeck David G, Graham Daniel B
Southwest Research Institute San Antonio TX USA.
Institute for Physical Science and Technology University of Maryland College Park MD USA.
Geophys Res Lett. 2019 Jul 28;46(14):7873-7882. doi: 10.1029/2019GL083361. Epub 2019 Jul 22.
MMS3 spacecraft passed the vicinity of the electron diffusion region of magnetotail reconnection on 3 July 2017, observing discrepancies between perpendicular electron bulk velocities and drift, and agyrotropic electron crescent distributions. Analyzing linear wave dispersions, Burch et al. (2019, https://doi.org/10.1029/2019GL082471) showed the electron crescent generates high-frequency waves. We investigate harmonics of upper-hybrid (UH) waves using both observation and particle-in-cell (PIC) simulation, and the generation of electromagnetic radiation from PIC simulation. Harmonics of UH are linearly polarized and propagate along the perpendicular direction to the ambient magnetic field. Compared with two-dimensional PIC simulation and nonlinear kinetic theory, we show that the nonlinear beam-plasma interaction between the agyrotropic electrons and the core electrons generates harmonics of UH. Moreover, PIC simulation shows that agyrotropic electron beam can lead to electromagnetic (EM) radiation at the plasma frequency and harmonics.
磁层多尺度（MMS）3号航天器于2017年7月3日经过磁尾重联电子扩散区附近，观测到垂直电子体速度与漂移之间的差异以及非旋电子月牙形分布。通过分析线性波色散，伯奇等人（2019年，https://doi.org/10.1029/2019GL082471）表明非旋电子月牙形会产生高频波。我们利用观测和粒子模拟（PIC）研究了上混合（UH）波的谐波以及PIC模拟中电磁辐射的产生。UH波的谐波是线偏振的，并沿与背景磁场垂直的方向传播。与二维PIC模拟和非线性动力学理论相比，我们表明非旋电子与核心电子之间的非线性束 - 等离子体相互作用会产生UH波的谐波。此外，PIC模拟表明非旋电子束可导致等离子体频率及其谐波处的电磁（EM）辐射。
