Modeling of Auroral Kilometric Radiation (AKR) Ordered Fine Structure via Electromagnetic and Electrostatic Ion Cyclotron (EMIC/EIC) Wave Stimulation and Particle Interaction

极光加速区的上行电流区是电子和离子加速、波粒相互作用、磁层-电离层（M-I）耦合和波产生的极动态区域。在这个区域可以观察到许多不同类型的等离子体波，包括强烈的静电和电磁离子回旋波。它也是极光公里辐射（AKR）的来源区域，AKR是最强大的地面无线电发射。该区域的向上电流被EIC和EMIC波干扰和调制，因此提供了M-I耦合动力学的重要组成部分。AKR的频率与时间谱图揭示了一个窄带状的精细结构，它看起来是湍流的，但显示出特定的频率漂移特征。了解AKR精细结构的来源对于理解波产生机制的细节和整体粒子/波能量平衡至关重要。最近发现了一类新的AKR精细结构，称为有序精细结构或条纹。新的数据表明，AKR的有序精细结构是由电磁离子回旋波和静电离子回旋波刺激形成的。本项目将使用三维粒子胞内（PIC）等离子体模拟代码来研究极光区EMIC/EIC波的生长和AKR有序精细结构的刺激。模拟确定了观察到的有序精细结构的形态如何取决于刺激AKR的波的频率和波长。这些模拟也将有助于空间和等离子体科学相关领域的发展。

The upward current region of the auroral acceleration region is an extremely dynamic region of electron and ion acceleration, wave-particle interaction, magnetospheric-ionospheric (M-I) coupling, and wave generation. In this region many different types of plasma waves are observed, including intense electrostatic and electromagnetic ion cyclotron (EIC/EMIC) waves. It is also the source region of auroral kilometric radiation (AKR), the most powerful terrestrial radio emission. Upward electric currents in this region are disrupted and modulated by EIC and EMIC waves, and thus provide a significant component of the M-I coupling dynamics. Frequency- vs. -time spectrograms of AKR reveal a narrow-banded fine structure that appears turbulent but displays specific features of frequency drift. Understanding the source of AKR fine structure is critical to understanding details of the wave generation mechanism, and the overall particle/wave energy balance. A new class of AKR fine structure referred to as ordered fine structure or striations has more recently been identified. The new data have suggests that AKR ordered fine structure results from stimulation by electromagnetic ion cyclotron (EMIC) and electrostatic ion cyclotron (EIC) waves. This project will use a 3-D particle-in-cell (PIC) plasma simulation code to study of the growth of EMIC/EIC waves in the auroral region and the stimulation of AKR ordered fine structure. The simulations determine how the morphology of the observed ordered fine structure depends on the frequency and wave length of the waves stimulating the AKR. The simulations will also contribute to developments in related fields of space and plasma science.