The relationship between field‐aligned currents and low‐frequency electromagnetic fluctuations
The relationship between field‐aligned currents and low‐frequency electromagnetic fluctuations
复制标题
场对准电流与低频电磁波动之间的关系
DOI：
10.1029/2003gl018292
复制
发表时间：
2003
影响因子：
5.2
通讯作者：
T. Xu
中科院分区：
文献类型：
--
作者：
C. Seyler;T. Xu
使用具有电子惯性的简化MHD描述，已经证明具有接近电子惯性长度c/ωp的横向尺度的电流片是不稳定的[ Seyler和Wu，2001 ]。这种强大的不稳定性源于平行电流的平流，其降低了导致涡流形成的磁能。不稳定性是局部的平行电流剪切和B的最大值附近。来自Freja、FAST和CLUSTER的观测表明，在电流切变最大化的区域，波动增强。模拟得到的谱比δE/δB和δE/δn与卫星资料一致。观测和模拟之间的一致性支持模拟结果作为BBELF（宽带极低频）波动的产生机制。
Current sheets having a transverse scale near the electron inertial length c/ωp have been shown to be unstable using a reduced MHD description with electron inertia [ Seyler and Wu, 2001 ]. This robust instability arises from the advection of the parallel current which lowers the magnetic energy resulting in vortex formation. The instability is localized where the parallel current shear and B⟂ are near a maximum. Observations from Freja, FAST, and CLUSTER show fluctuation enhancement in regions where current shear maximizes. The simulation spectral ratios δE/δB and δE/δn are found to be consistent with satellite data. The agreement between observations and simulations support the simulation results as the generation mechanism of BBELF (broad‐band extremely low‐frequency) fluctuations.