论文标题
帕克螺旋几何形状和相关磁场线长度的湍流的分析模型
An analytical model of turbulence in Parker spiral geometry and associated magnetic field line lengths
论文作者
论文摘要
了解从太阳到星际空间的磁连接对于将原位粒子观测到与颗粒的太阳源区域联系起来至关重要。沿大规模的Parker螺旋磁场的简单连接通过磁场线的湍流随机行走使其复杂。在本文中，我们介绍了地球层磁场的第一个分析模型，其中湍流的主要2D成分横向到Parker螺旋。 2D波场补充了一个次要波场成分，该组件在大小的大型中心距离处具有渐近的平板几何形状。我们表明，湍流将野外线从太阳的一个小源区域传播到16 $^\ circ $ heliolongutinal和-latududinal范围，在1〜AU处，具有标准的田间线的角度偏差$ 14^\ Circ $。小源区域映射到1〜AU的间歇性纵向和纬度范围，与太阳能粒子强度的辍学一致。野外线的长度从标称的Parker螺旋长度显着延伸至1.6〜AU，其野外线的野外线比靠近太阳能磁盘中心的那些源更长。我们讨论了我们发现对理解带电颗粒传播的含义，以及了解靠近太阳的湍流特性的重要性。
Understanding the magnetic connections from the Sun to interplanetary space is crucial for linking in situ particle observations with the solar source regions of the particles. A simple connection along the large-scale Parker spiral magnetic field is made complex by the turbulent random-walk of field lines. In this paper, we present the first analytical model of heliospheric magnetic fields where the dominant 2D component of the turbulence is transverse to the Parker spiral. The 2D wave field is supplemented with a minor wave field component that has asymptotically slab geometry at small and large heliocentric distances. We show that turbulence spreads field lines from a small source region at the Sun to a 60$^\circ$ heliolongitudinal and -latitudinal range at 1~au, with standard deviation of the angular spread of the field lines $14^\circ$. Small source regions map to an intermittent range of longitudes and latitudes at 1~au, consistent with dropouts in solar energetic particle intensities. The lengths of the field lines are significantly extended from the nominal Parker spiral length of 1.17~au up to 1.6~au, with field lines from sources at and behind the west limb considerably longer than those closer to the solar disk centre. We discuss the implications of our findings on understanding charged particle propagation, and the importance of understanding the turbulence properties close to the Sun.
