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MMS Observations of Broadband Electrostatic Waves in Electron Diffusion Region of Magnetotail Reconnection
Author(s) -
Yu Xiancai,
Lu Quanming,
Wang Rongsheng,
Huang Kai,
Gao Xinliang,
Wang Shui
Publication year - 2021
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2020ja028882
Subject(s) - physics , instability , electric field , electron , diffusion , computational physics , plasma , waveform , whistler , atomic physics , optics , mechanics , voltage , quantum mechanics , thermodynamics
In this study, the broadband electrostatic waves are observed in electron diffusion region (EDR). Detailed analysis has shown that the parallel electric field of these waves have a bipolar or continuous steepening waveform. The bipolar structures of the parallel electric field are usually accompanied by electron holes (EHs) in phase space. The parallel spatial scalesl | |of EHs are ∼3–5λ D( λ Dis the Debye length), and the perpendicular spatial scalesl ⊥are larger than ∼18.6λ D . Therefore, the length ratiosl ⊥ / l | |are larger than ∼3.7–6.2, which means that the EHs have oblate shapes. Associated with these plasma waves, electron beams propagating away from the X‐line have been observed. By performing a one‐dimensional (1‐D) electrostatic particle‐in‐cell simulation of the bump‐on‐tail instability, we reproduce two types of waveforms similar to those observed in the EDR during the different evolution stage of the instability, which implies that these electrostatic waves are generated by the bump‐on‐tail instabilities.