Electron Acceleration via Trapping inside Ion Mirror-mode Structures within A Large-scale Magnetic Flux Rope

Fuente: arXiv
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Main Authors: Zhong, Z. H., Zhang, H., Zhou, M., Graham, D. B., Tang, R. X., Deng, X. H., Khotyaintsev, Yu. V.
Format: Preprint
Published: 2025
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author Zhong, Z. H.
Zhang, H.
Zhou, M.
Graham, D. B.
Tang, R. X.
Deng, X. H.
Khotyaintsev, Yu. V.
author_facet Zhong, Z. H.
Zhang, H.
Zhou, M.
Graham, D. B.
Tang, R. X.
Deng, X. H.
Khotyaintsev, Yu. V.
contents Fermi acceleration is believed as a crucial process for the acceleration of energetic electrons within flux ropes (FRs) during magnetic reconnection. However, in finite-length FRs with a large core field, the finite contracting and the escaping of electrons along the axis can significantly limit the efficiency of Fermi acceleration. Using observations from the Magnetospheric Multiscale mission in the magnetotail, we demonstrate that magnetic mirror structures inside the FR can effectively prevent the escape of energetic electrons and overcome the limitation of finite contraction. Energetic electrons were produced and formed a power-law energy distribution in these mirror structures. By evaluating the acceleration rates, we show that these energetic electrons can be continuously accelerated within the mirror structures near the central region of the FR. These results unveil a novel mechanism that is universally applicable to electron acceleration within FRs in space, laboratory, and astrophysical plasmas.
format Preprint
id arxiv_https___arxiv_org_abs_2506_09754
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Electron Acceleration via Trapping inside Ion Mirror-mode Structures within A Large-scale Magnetic Flux Rope
Zhong, Z. H.
Zhang, H.
Zhou, M.
Graham, D. B.
Tang, R. X.
Deng, X. H.
Khotyaintsev, Yu. V.
Space Physics
Fermi acceleration is believed as a crucial process for the acceleration of energetic electrons within flux ropes (FRs) during magnetic reconnection. However, in finite-length FRs with a large core field, the finite contracting and the escaping of electrons along the axis can significantly limit the efficiency of Fermi acceleration. Using observations from the Magnetospheric Multiscale mission in the magnetotail, we demonstrate that magnetic mirror structures inside the FR can effectively prevent the escape of energetic electrons and overcome the limitation of finite contraction. Energetic electrons were produced and formed a power-law energy distribution in these mirror structures. By evaluating the acceleration rates, we show that these energetic electrons can be continuously accelerated within the mirror structures near the central region of the FR. These results unveil a novel mechanism that is universally applicable to electron acceleration within FRs in space, laboratory, and astrophysical plasmas.
title Electron Acceleration via Trapping inside Ion Mirror-mode Structures within A Large-scale Magnetic Flux Rope
topic Space Physics
url https://arxiv.org/abs/2506.09754