Occurrence of Flat-top Electron Velocity Distributions in Magnetotail Plasma Jets
Abstract
Non-Maxwellian electron velocity distributions (eVDFs) are ubiquitous in collisionless plasmas. For example, various types of non-Maxwellian eVDFs exist in magnetic reconnection jets in the Earth's magnetotail. At thermal energies, eVDF can be flat-topped due to electron trapping associated with magnetic reconnection. However, the occurrence of such eVDFs in magnetotail reconnection remains largely unconstrained. Here, we statistically investigate flat-top eVDFs in fast plasma jets in the magnetotail using a new method for classifying eVDFs. We show that only of the eVDFs in the jets are flat-tops. Nevertheless, we find that most jets exhibit flat-top eVDFs, indicating that this signature of parallel acceleration and electron streaming is characteristic of the jets. We find that these flat-top eVDFs are localized within an ion-inertial-length-scale region near the edges of the current sheet and close to the reconnection region. Our results highlight the importance of flat-top eVDFs in non-local thermodynamic equilibrium collisionless plasmas.
Keywords
Cite
@article{arxiv.2604.05992,
title = {Occurrence of Flat-top Electron Velocity Distributions in Magnetotail Plasma Jets},
author = {Louis Richard and Yuri V. Khotyaintsev and Cecilia Norgren},
journal= {arXiv preprint arXiv:2604.05992},
year = {2026}
}