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ORIGINAL RESEARCH article

Front. Phys.
Sec. Space Physics
Volume 12 - 2024 | doi: 10.3389/fphy.2024.1446646
This article is part of the Research Topic Variability in the Solar Wind and its Impact on the Coupled Magnetosphere-Ionosphere-Thermosphere System View all 6 articles

Study of the Characteristics of Electron Firehose Unstable Conditions in the Terrestrial Magnetotail Plasma Sheet

Provisionally accepted
Jiayun Wei Jiayun Wei Guoqiang Wang Guoqiang Wang *Pingbing Zuo Pingbing Zuo *
  • Institute of Space Science and Applied Technology, Harbin Institute of Technology, Shenzhen, Guangdong, China

The final, formatted version of the article will be published soon.

    Electron firehose instabilities can be excited at dipolarization fronts and in the magnetic reconnection outflow in the terrestrial magnetotail, but their occurrence rate in the plasma sheet is unclear. Here, we investigate the characteristics of electron firehose unstable conditions in the magnetotail plasma sheet based on observations of the Magnetospheric Multiscale mission. We find an Alfvé nic magnetic field fluctuation accompanied by a strong field-aligned current during a flapping motion. This fluctuation occurs where the local plasma is electron firehose unstable, indicating that the electron firehose 2 instability might be one origin of the field-aligned current during flapping motions. We statistically find that the local plasma near the neutral sheet has a small probability with the maximum value < 1.4% to be electron firehose unstable, which mainly occurs in the central plasma sheet with BXY/BL < 0.3.The maximum probability of Tef > 0 (electron firehose unstable condition) is ~1.36% (1.32%) at BXY/BL  0.05 (0.15) during fast (non-fast) flows. During fast flows, the plasma near the neutral sheet tends to have a higher probability of Tef > 0 when the local VT is larger. During non-fast flows, the plasma near the neutral sheet tends to have a higher probability of Tef > 0 when Te is larger. The probability of Tef > 0 shows a dawn-dusk asymmetry during fast flows and non-fast flows. In addition, the probability of Tef > 0 during fast flows tends to be larger when the ambient BZ is weak, which shows opposite characteristics during non-fast flows. These findings help to assess the importance of the role of electron firehose instabilities in the magnetotail plasma sheet.

    Keywords: Electron firehose unstable1, magnetic field fluctuation2, plasma sheet3, fast flow4, nonfast flow5

    Received: 10 Jun 2024; Accepted: 13 Sep 2024.

    Copyright: © 2024 Wei, Wang and Zuo. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Guoqiang Wang, Institute of Space Science and Applied Technology, Harbin Institute of Technology, Shenzhen, 518000, Guangdong, China
    Pingbing Zuo, Institute of Space Science and Applied Technology, Harbin Institute of Technology, Shenzhen, 518000, Guangdong, China

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