Plasma and Magnetic-Field Structure of the Solar Wind at Inertial-Range Scale Sizes Discerned From Statistical Examinations of the Time-Series Measurements
Plasma and Magnetic-Field Structure of the Solar Wind at Inertial-Range Scale Sizes Discerned From Statistical Examinations of the Time-Series Measurements
复制标题
DOI：
10.3389/fspas.2020.00020
复制
发表时间：
2020-05
期刊：
影响因子：
--
通讯作者：
J. Borovsky
中科院分区：
文献类型：
--
作者：
J. Borovsky
本文综述了空间尺度惯性范围（500-5 × 106 km）内太阳风的磁场和等离子体结构的性质，对应于从1秒到几小时的航天器时间尺度，并对1 Au的航天器数据集进行了统计分析，以确定结构性质。太阳风的磁结构通常具有磁通管结构，磁通管壁是强电流片，磁场方向在管与管之间变化很大。磁管还表现出不同的等离子体性质（例如，数密度，比熵），这些性质从管到管的变化。离子组成也因管而异，电子热通量的值也是如此。当太阳风是阿尔夫维尼克时，太阳风的磁结构从太阳向外移动的速度比质子等离子体快。在随着结构向外移动的参考系中，在每个通量管内存在不同的场对准的等离子体流。在随磁场结构运动的坐标系中，垂直于磁场的速度分量近似为零;这表明磁场结构在从太阳向外运动时几乎没有演化。当磁场旋转和场向流旋转时，在磁通量管之间的边界上可以看到大的突然速度剪切。研究了太阳风电流片对太阳风磁功率谱密度的影响，发现电流片主导太阳风的谱特性。
This paper reviews the properties of the magnetic and plasma structure of the solar wind in the inertial range of spatial scales (500–5 × 106 km), corresponding to spacecraft timescales from 1 s to a few hr. Spacecraft data sets at 1 AU have been statistically analyzed to determine the structure properties. The magnetic structure of the solar wind often has a flux-tube texture, with the magnetic flux tube walls being strong current sheets and the field orientation varying strongly from tube to tube. The magnetic tubes also exhibit distinct plasma properties (e.g., number density, specific entropy), with variations in those properties from tube to tube. The ion composition also varies from tube to tube, as does the value of the electron heat flux. When the solar wind is Alfvénic, the magnetic structure of the solar wind moves outward from the Sun faster than the proton plasma does. In the reference frame moving outward with the structure, there are distinct field-aligned plasma flows within each flux tube. In the frame moving with the magnetic structure the velocity component perpendicular to the field is approximately zero; this indicates that there is little or no evolution of the magnetic structure as it moves outward from the Sun. Large sudden velocity shears are seen across the boundaries between the magnetic flux tubes as the magnetic field rotates and the field-aligned flow rotates. The effect of the solar-wind current sheets on the magnetic power spectral density of the solar wind is examined: the current sheets are found to dominate the spectral properties of the solar wind.