论文标题
离子尺度的电流结构在短大振幅磁性结构中
Ion-scale current structures in Short Large-Amplitude Magnetic Structures
论文作者
论文摘要
我们研究了磁层多尺度任务观察到的陆生离子前壳区域中短振幅磁性结构（猛击）中的电流结构。具有强度电流的结构（| J | 〜1μa/m^2）的比例长度可与局部离子惯性长度（DI）相当。一种电流的结构类型是由于猛击的磁场旋转而导致的，这些电流板的子集可以表现出重新连接的特征，包括电子流出射流和X线型磁性拓扑。猛击边缘附近的DI尺度电流比整体猛击的传播速度要慢得多，这表明它可能是由压缩引起的。当前的结构也以FCI <f <flH为单位的磁通惠斯勒波，其中FCI和FLH分别是离子回旋频率和较低的杂交频率。当前床单和惠斯勒波的场旋转产生了可比的| J |和能量转换率。在一个嵌入大型猛击电流板中的一个惠斯勒数据包中清楚地观察到电子加热，在该数据包中，平行电场和曲率与电场相反的曲率漂移。结果可以洞悉电流结构的产生，并在冲击过渡区域薄电流结构处的能量转化。
We investigate electric current structures in Short Large-Amplitude Magnetic Structures (SLAMS) in the terrestrial ion foreshock region observed by the Magnetospheric Multiscale mission. The structures with intense currents (|J|~1 μA/m^2) have scale lengths comparable to the local ion inertial length (di). One current structure type is a current sheet due to the magnetic field rotation of the SLAMS, and a subset of these current sheets can exhibit reconnection features including the electron outflow jet and X-line-type magnetic topology. The di-scale current sheet near the edge of a SLAMS propagates much more slowly than the overall SLAMS, suggesting that it may result from compression. The current structures also exist as magnetosonic whistler waves with fci < f < flh, where fci and flh are the ion cyclotron frequency and the lower-hybrid frequency, respectively. The field rotations in the current sheets and whistler waves generate comparable |J| and energy conversion rates. Electron heating is clearly observed in one whistler packet embedded in a larger-scale current sheet of the SLAMS, where the parallel electric field and the curvature drift opposite to the electric field energize electrons. The results give insight about the thin current structure generation and energy conversion at thin current structures in the shock transition region.
