Subion‐Scale Flux Rope Nested Inside Ion‐Scale Flux Rope in Earth's Magnetotail. Issue 23 (30th November 2021)

• Record Type: Journal Article
• Authors: He, R. J.; Fu, H. S.; Liu, Y. Y.; Wang, Z.; Liu, C. M.
• Is Part Of: Geophysical research letters. Volume 48:Issue 23(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-11-30
• Subjects: magnetic reconnection -- flux rope -- cross scale -- energy cascade; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2021GL096169
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Magnetic flux ropes (MFRs)—transient magnetic structures widely observed in Earth's magnetosphere—play crucial roles in particle acceleration and energy dissipation. MFRs above ion scale have been well studied, while MFRs at subion scales and their coupling with larger‐scale ropes still remains not well understood. In this paper, we present the first observation of a subion‐scale MFR nested in an ion‐scale MFR, using high‐resolution data from the magnetospheric multiscale (MMS) mission. We find that the subion‐scale MFR hosts more intense plasma activity than the ion‐scale MFR, including distinct electron agyrotropy and strong electromagnetic turbulence. In addition, axis of the subion‐scale MFR is oblique to that of the ion‐scale MFR, indicating that their generation may be ascribed to 3D magnetic reconnection. Observations of such cross‐scale structure may shed new lights into understanding energy cascade in space plasmas. Plain Language Summary: In this study, we report the first observation of a subion‐scale flux rope nested in an ion‐scale flux rope in Earth's magnetotail and resolve their dynamics and properties in great detail by using high‐cadence data from the MMS mission. We find that the two ropes have different properties, for instance, the smaller‐scale rope hosts stronger plasma activity. This study can improve our understanding of cross‐scale coupling of the magnetic flux ropes and energy cascade in space plasmas. Key Points: A subion‐scale flux rope nested in an ion‐scale flux rope is reported for the first time The subion‐scale rope hosts more intense waves than the ion‐scale rope does Such cross‐scale structure may result from 3D magnetic reconnection and play a crucial role in energy cascade in space plasmas