• ISSN 2097-1893
  • CN 10-1855/P
郭志忠,符慧山,刘杨洋. 2022. 火星空间环境中电子通量的统计研究. 地球与行星物理论评,53(4):488-496. doi: 10.19975/j.dqyxx.2022-004
引用本文: 郭志忠,符慧山,刘杨洋. 2022. 火星空间环境中电子通量的统计研究. 地球与行星物理论评,53(4):488-496. doi: 10.19975/j.dqyxx.2022-004
Guo Z Z, Fu H S, Liu Y Y. 2022. Statistical study of electron flux in Martian space environment. Reviews of Geophysics and Planetary Physics, 53(4): 488-496. doi: 10.19975/j.dqyxx.2022-004
Citation: Guo Z Z, Fu H S, Liu Y Y. 2022. Statistical study of electron flux in Martian space environment. Reviews of Geophysics and Planetary Physics, 53(4): 488-496. doi: 10.19975/j.dqyxx.2022-004

火星空间环境中电子通量的统计研究

Statistical study of electron flux in Martian space environment

  • 摘要: 火星空间环境中不同区域的电子分布在行星演化过程中扮演了重要的角色. 然而,整个火星空间环境中电子的分布情况目前还不清楚. 本文使用MAVEN航天器2015~2020年共6年的观测数据,统计研究了不同能量(30~5000 eV和20~1000 keV)的电子对应的微分能量通量在整个火星空间环境中的分布. 通过统计研究,我们发现30~1000 eV范围的电子主要分布在磁鞘中. 其中,30~50 eV范围的电子在远磁尾−2.8RM <XMSO < −2RM、−1RM < YMSO <1RM、−1RM < ZMSO <1RM区域的通量显著降低,50~100 eV范围的电子通量在整个磁尾区域都比较低. 100~1000 eV范围的电子主要集中分布在感应磁层顶上游−1RM < YMSO < 1RM、−1.5RM < ZMSO < 1.5RM 区域,该分布特征100~500 eV范围的电子最为明显. 而1000~5000 eV范围,通量达105 eV/(cm2·s·sr·eV)以上的高能电子出现在火星磁鞘和弓激波附近以及远磁尾区域(−2.8RM < XMSO <−2RM、−2RM < YMSO < 2RM、−1RM < ZMSO < 1RM);并且在这些区域,20~1000 keV范围的高能电子通量也达到102 keV/(cm2·s·sr·keV)以上. 另外,20~1000 keV范围的通量在102 keV/(cm2·s·sr·keV)以上的高能电子在火星空间环境中的分布非常离散.

     

    Abstract: The distributions of electrons at different regions in the Martian space environment play a significant role in the planet's evolution. However, the distributions of electrons in the entire Martian space remain unclear. Here, using MAVEN data during 2015~2020, we statistically study the distributions of differential energy fluxes (DEFs) corresponding to electrons in different energy ranges throughout the Martian space environment. Magnetic field and position data are provided by the MAVEN Magnetometer. The MAVEN Solar Wind Electron Analyzer provides the electron differential energy fluxes in the range of 3~5000 eV. Furthermore, the MAVEN Solar Energetic Particle instrument provides the fluxes of energetic electrons from 20 to 1000 keV. All the data are presented in Mars Solar Orbital (MSO) coordinates. We find that the 30~1000 eV electrons are mainly distributed in the induced magnetosheath. For the same energy ranges of the DEFs, the 30~50 eV electron DEFs are significantly lower in the far magnetotail region (−2.8RM <XMSO < −2RM, −1RM < YMSO <1RM, −1RM < ZMSO <1RM), ~106.5 eV/(cm2·s·sr·eV). Throughout the magneto tail, DEFs in the 50~100 eV range are lower. Not only on both sides of the dawn and dusk, but also on the north and south sides, the DEFs in the range of 30~100 eV are symmetrical. The 100~1000 eV electrons are mainly concentrated in the region of −1RM < YMSO < 1RM, −1.5RM < ZMSO < 1.5RM upstream of the top of the induced magnetosphere, and this distribution feature is most obvious in the range of 100~500 eV electrons. The DEFs of electrons in the 500~1000 eV range are very low in the near-Mars magnetotail region (−2RM < XMSO < −1RM), but increase slightly in parts of the far magnetotail (−2.8RM < XMSO < −2RM). And high energy electrons in the 1000~5000 eV range with DEFs up to 105 eV/(cm2·s·sr·eV) or more occur near the Martian magnetosheath and bow shock, with a small amount in the far magnetotail region (−2.8RM < XMSO < −2RM, −2RM < YMSO < 2RM, −1RM < ZMSO < 1RM). In these regions, the energetic electron DEFs in the 20~1000 keV range also reach above 102 keV/(cm2·s·sr·keV). But these energetic electrons with DEFs above 102 keV/(cm2·s·sr·keV) have a very discrete distribution in Martian space. Additionally, statistical results show that the increase of partial high-energy electron DEFs in the far magnetotail region (−2.8RM < XMSO < −2RM) is correlated with the local magnetic field strength. In areas with high magnetic field strength, the corresponding 500~5000 eV and 20~1000 keV electron DEFs also increase accordingly. Finally, we discuss possible mechanisms for the excitation of high-energy electrons in the Martian magnetotail and list our statistical conclusions.

     

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