The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft regularly observed the magnetospheric flanks of Mercury during its orbital phase. Data from the Magnetometer (MAG) and the Fast Imaging Plasma Spectrometer (FIPS) allow us to investigate the statistical properties of planetary ions (Na⁺) in the presence of Kelvin‐Helmholtz (KH) waves at the duskside magnetopause. We collect the data from orbits with clear signatures of KH waves under northward interplanetary magnetic field, as well as from adjacent orbits that do not have KH signatures, and we compare the energy characteristics between the KH and non‐KH events. Although low planetary counts in FIPS data make the comparison of these characteristics difficult, we find that in the presence of KH waves: (1) large counts of planetary ions are observed and (2) differences in Na⁺ energy spectra are only seen inside the magnetosphere, where they show a deceleration signature for ions with energies above 2.0 keV/e. These results suggest that planetary ions are not escaping from the magnetosphere and that electric field structures related to KH waves can decelerate planetary ions originating from the magnetotail region. The understanding of the energy distribution of planetary ions in the magnetospheric flanks of Mercury is important for a better understanding of plasma convection in the magnetosphere.

中文翻译：

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汞在开尔文-亥姆霍兹涡旋附近的行星离子特征的信使观测

水星表面，太空环境，地球化学和测距（MESSENGER）航天器在其轨道阶段定期观测水星的磁层侧面。来自磁力仪（MAG）和快速成像等离子体光谱仪（FIPS）的数据使我们能够研究行星离子（Na ⁺）在黄昏的磁层顶上存在开尔文-亥姆霍兹（KH）波的情况。我们从在北向行星际磁场下具有清晰KH波特征的轨道以及不具有KH特征的相邻轨道收集数据，并且比较KH事件和非KH事件之间的能量特征。尽管FIPS数据中的低行星数使这些特征的比较变得困难，但我们发现在存在KH波的情况下：（1）观测到大量的行星离子，（2）Na ^+的差异能谱仅在磁层内部可见，它们对能量高于2.0 keV / e的离子显示出减速特征。这些结果表明，行星离子并未从磁层逃逸，与KH波相关的电场结构可使来自磁尾区域的行星离子减速。了解汞在磁层两侧的行星离子的能量分布对于更好地了解磁层中的等离子体对流非常重要。