帕克太阳探测器观测到的两个极近距离磁开关的微物理多样性
Microphysical Diversity in Two Very Closely Spaced Magnetic Switchbacks Observed by Parker Solar Probe
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- Sardar Vallabhbhai National Institute of Technology（萨达尔·瓦拉巴伊国立技术学院）
- Vikram Sarabhai Space Centre（维克拉姆·萨拉巴伊航天中心）
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中文总结 AI 辅助
本研究通过帕克太阳探测器数据分析两个邻近磁开关，发现其微物理特性（如质子温度、波动幅度和间歇性）存在差异，表明磁开关是动态结构，内部湍流可能驱动局部加热。
中文摘要 AI 辅助
帕克太阳探测器在太阳附近的观测揭示了频繁发生的磁场突然反转现象，即磁开关（SBs）。尽管这些现象普遍存在，但其内部等离子体结构和相关加热机制仍知之甚少。我们针对2020年1月24日观测到的两个紧密相邻的磁开关（文中称为SB_1和SB_2）进行了案例研究，使用了高时间分辨率的磁场和等离子体测量数据。磁波动被分解为平行和垂直于平均场的分量，并分析其功率谱以表征湍流级联。应用增量偏方差（PVI）方法识别间歇性的电流片状结构。两个SB区间均表现出清晰的阿尔芬特性和增强的径向流；然而，它们的微观物理过程有所不同：与SB_2相比，SB_1显示出更高的质子温度、更大的波动幅度和更密集的电流片群体。这两个事件的光谱指数也不同，SB_1的垂直斜率比SB_2更陡。SB_1中增强的间歇性、质子温度以及瞬时的β > 1偏移表明，小尺度结构处的局部耗散是观测到的加热现象的一个合理驱动因素。这些发现表明，磁开关并非均匀的运动学偏转，而是动态演化的等离子体结构，其内部湍流可能调节局部能量转换，并有助于近太阳太阳风的空间间歇性加热。
英文摘要
Parker Solar Probe observations near the Sun reveal frequent, sudden reversals of the magnetic field known as switchbacks (SBs). Despite their ubiquity, the internal plasma structure and associated heating within SBs remain poorly understood. We present a case study of two closely spaced SBs (referred in text as SB_1 and SB_2) observed on 24 January 2020 using high-cadence magnetic and plasma measurements. Magnetic fluctuations are decomposed into components parallel and perpendicular to the mean field, and their power spectra are analyzed to characterize the turbulent cascade. The Partial Variance of Increments (PVI) method is applied to identify intermittent current-sheet-like features. Both SB intervals exhibit clear Alfvenic behavior and enhanced radial flow; however, their microphysics differ: SB_1 shows a higher proton temperature, larger fluctuation amplitudes, and a denser population of current sheets compared to SB_2. The two events also differ in spectral index, with SB_1 exhibiting a steeper perpendicular slope than SB_2. The elevated intermittency, proton temperature, and transient $β> 1$ excursion in SB_1 suggest that localized dissipation at small-scale structures is a plausible driver of the observed heating. These findings demonstrate that SBs are not uniform kinematic deflections but dynamically evolving plasma structures whose internal turbulence may regulate local energy conversion and contribute to the spatially intermittent heating of the near-Sun solar wind.
