论文标题
在湍流驱动的磁重新连接中,各向异性电子加热
Anisotropic electron heating in turbulence-driven magnetic reconnection in the near-Sun solar wind
论文作者
论文摘要
我们对具有观察驱动条件的湍流等离子体系统进行高分辨率的二维全运动数值模拟,以研究湍流,磁重新连接和从离子加热到从离子到亚电体量表中的粒子加热之间的相互作用。我们发现,湍流等离子体和电磁波动的功率光谱显示出多个幂律间隔,低于电子吉拉迪乌斯小的尺度。观察到磁重新连接发生在电子惯性长度的厚度的电流板的对应关系中,由于离子尺度涡流而形成和收缩。在某些情况下,观察到离子和电子流出(经典的重新连接场景),而在其他情况下 - 通常是最短的电流表 - 仅是电子喷气机(“仅电子重新连接”)。在重新连接开始时,电子温度开始升高,并且会出现强烈的平行温度各向异性。这表明,在强湍流中,电子尺度的相干结构对电子加热可能起重要作用,因为磁性和局部现象(例如磁重新连接)可能比与与波浪样波动相互作用相关的阻尼机制将能量从电磁场转移到颗粒上。
We perform a high-resolution two-dimensional fully-kinetic numerical simulation of a turbulent plasma system with observation-driven conditions, in order to investigate the interplay between turbulence, magnetic reconnection, and particle heating from ion to sub-electron scales in the near-Sun solar wind. We find that the power spectra of the turbulent plasma and electromagnetic fluctuations show multiple power-law intervals down to scales smaller than the electron gyroradius. Magnetic reconnection is observed to occur in correspondence of current sheets with a thickness of the order of the electron inertial length, which form and shrink due to interacting ion-scale vortexes. In some cases, both ion and electron outflows are observed (the classic reconnection scenario), while in others -- typically for the shortest current sheets -- only electron jets are presents ("electron-only reconnection"). At the onset of reconnection, the electron temperature starts to increase and a strong parallel temperature anisotropy develops. This suggests that in strong turbulence electron-scale coherent structures may play a significant role for electron heating, as impulsive and localized phenomena such as magnetic reconnection may transfer energy from the electromagnetic fields to particles more efficiently than damping mechanisms related to interactions with wave-like fluctuations.