Subion‐Scale Flux Rope Nested Inside Ion‐Scale Flux Rope in Earth's Magnetotail

He, R. J.; Fu, H. S.; Liu, Y. Y.; Wang, Z.; Liu, C. M.

doi:10.1029/2021gl096169

Cited by 5 publications

(6 citation statements)

References 72 publications

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“…Ion energy flux (0.1-100 keV) (Figure 4(d)) dramatically increases by 2-4 orders of magnitude inside the MFR. The transient trends resemble the typical characteristics of an MFR often observed or simulated in the magnetotail (Lin et al 2014;Lu et al 2019;He et al 2021;Zhang et al 2021). That is, the evolution of flux ropes in the magnetotail can lead to ion acceleration.…”

Section: Ion Accelerationsupporting

confidence: 62%

“…Such MFRs at magnetopause have four possible topologies inferred from electron pitch-angle distributions (Pu et al 2013), and often consist of two interlinked flux tubes (Hwang et al 2021). He et al (2021) found a subion-scale MFR nested within an ion-scale MFR in magnetotail, where their axes are perpendicular to each other. Chen et al (2021) reported an electron-scale MFR in the electron diffusion region and reconstructed its 3D magnetic field topology.…”

Section: Introductionmentioning

confidence: 92%

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The Role of Magnetic Flux Rope in Ion Acceleration: MHD Simulations and Test-particle Tracing

Bai

et al. 2022

ApJ

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Magnetic flux ropes (MFRs), playing a crucial role in particle energization and energy transport in the solar–terrestrial space, are helical structures produced by magnetic reconnection. It has been both theoretically predicted and observationally confirmed that MFRs and associated processes are inherently three-dimensional in space. Although such structures have been widely suggested as a favorable place for electron acceleration, whether large-scale MFRs can lead to ion acceleration has been rarely investigated. In this study, an MHD model is used to examine the evolution of large-scale MFRs in the magnetotail, and a test-particle simulation is further employed to study the associated ion energization. Results show that magnetic reconnections take place at multiple X-lines in the magnetotail current sheet, generating a twisted MFR with a scale of about 10 R e in azimuth. It propagates earthward following the tail reconnection but its east and west wings are significantly distorted azimuthally. Test-particle tracing reveals that ions (0.1–100 keV) can be trapped within the rope while being effectively accelerated. The rope therefore brings in energetic plasma sources into the inner magnetosphere as it transports earthward. These results demonstrate that the MFR is an important source carrier for the ring-current formation in the inner magnetosphere.

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Section: Ion Accelerationsupporting

confidence: 62%

Section: Introductionmentioning

confidence: 92%

The Role of Magnetic Flux Rope in Ion Acceleration: MHD Simulations and Test-particle Tracing

Bai

et al. 2022

ApJ

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“…In this sense, it is quite reasonable for the FOTE method to find a twisted structure without the bipolar signature in the time‐serious spacecraft data. It's clearly found that the topology of this twisted magnetic structure is not the reconnection current sheet, which has an “X‐shape” topology (Fu et al., 2016; Fu, Wang, et al., 2020; Z. Wang et al., 2020, 2022; Zhang et al., 2023), and O‐lines, which is consisted of spiral magnetic field lines (Eastwood et al., 2016; He et al., 2021; Hwang et al., 2021; Øieroset et al., 2016; R. Wang et al., 2016; Z. Wang, Vaivads, Fu, Cao, Lindberg, et al., 2023; Z. Wang, Vaivads, Fu, Cao, & Liu, 2023), including magnetic flux ropes and magnetic islands. And it's also certainly not a nonlinear structure such like a magnetic hole (Liu, Fu, Olshevsky, et al., 2019; Liu et al., 2020; Yu et al., 2023).…”

Section: Observationmentioning

confidence: 99%

Energy Conversion by a Twisted Magnetic Structure at Magnetopause Boundary Layer: MMS Observations

Du,

Fu,

Wang

et al. 2023

Geophysical Research Letters

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The Earth's magnetopause is an ion‐scale boundary that separates the magnetosphere from the shocked solar wind. At such boundary, energy‐conversion processes frequently occur. Previous studies suggested that such energy conversions are related to the magnetic reconnection process. Here, we report a new mechanism that the coaction between the twisted magnetic structure and lower‐hybrid waves can also drive energy conversion (J⋅ E, J is current density and E is electric field) at the magnetopause boundary layer, by using high‐resolution measurements of the four Magnetospheric Multiscale spacecraft. We find that such energy conversion is efficient (with magnitude up to 20 nW/m3) and is attributed to an intense current filament (j ≈ 3,800 nA/m2) and a fluctuating electric field driven by lower‐hybrid waves. With the help of the First‐Order Taylor Expansion method, we find that the intense current filament is driven by a twisted magnetic structure at electron scale. Our study improves the understanding of energy‐conversion processes at the Earth's magnetopause.

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“…Multipoint spacecraft observations showed that the magnetic structures associated with the earthward and tailward bulk flows can be formed at ion and sub-ion kinetic scales and/or have very thin fronts/boundaries with a characteristic thickness of the order of ion gyroradius or less (Sergeev et al 2009;Balikhin et al 2014;Huang et al 2016;Grigorenko et al 2018;He et al 2021). These structures can be the sites of strong energy dissipation (e.g., Drake et al 2006;Fu et al 2006;Oka et al 2010;Huang et al 2019), which affects the particle velocity distribution functions and causes the generation of various types of electromagnetic and electrostatic wave modes (e.g., Zhang et al 1999;Le Contel et al 2009;Tenerani et al 2013;Fujimoto 2014Fujimoto , 2017Zhang & Angelopoulos 2014;Grigorenko et al 2016;Huang et al 2016;Wang et al 2016;Guo et al 2021;Pickett 2021).…”

Section: Introductionmentioning

confidence: 99%

Quasi-parallel Whistler Waves and Their Interaction with Resonant Electrons during High-velocity Bulk Flows in the Earth’s Magnetotail

Григоренко

Malykhin

Kronberg

et al. 2023

ApJ

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In collisionless space, plasma waves are important channels of energy conversion, affecting the local particle velocity distribution functions through wave–particle interactions. In this paper we present a comparative statistical analysis of the characteristics of quasi-parallel narrowband whistler waves and the properties of resonant electrons interacting with these waves during the intervals of earthward and tailward high-velocity bulk flows produced by the near-Earth X-line and observed by Magnetospheric Multiscale Mission spacecraft. We found that on both sides of the X-line, the suprathermal electrons (≥1 keV) having large pitch angles make the major contribution to the maximal growth rate (γ) of these waves. The whistler waves were observed almost simultaneously with strong enhancements of perpendicular magnetic gradients localized at electron scales near dipolarization fronts associated with the earthward bulk flows, and near flux ropes/magnetic islands embedded into the tailward bulk flows. Betatron energization of electrons due to the appearance of such gradients increases the perpendicular anisotropy of electron distribution, which could be responsible for the whistler wave generation. We found that in the course of electron interactions with the whistler waves the lower-energy resonant electrons can transfer a part of their kinetic energy to the higher-energy electrons, especially in the Central Plasma Sheet. This results in formation/enhancement of energy-dependent perpendicular anisotropy and power-law tails in the high-energy range of electron velocity distribution. We conclude that despite the differences in the magnetic structure of the earthward and tailward bulk flows, the mechanisms of the quasi-parallel whistler wave generation and the properties of resonant electrons are quite similar.

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Subion‐Scale Flux Rope Nested Inside Ion‐Scale Flux Rope in Earth's Magnetotail

Cited by 5 publications

References 72 publications

The Role of Magnetic Flux Rope in Ion Acceleration: MHD Simulations and Test-particle Tracing

The Role of Magnetic Flux Rope in Ion Acceleration: MHD Simulations and Test-particle Tracing

Energy Conversion by a Twisted Magnetic Structure at Magnetopause Boundary Layer: MMS Observations

Quasi-parallel Whistler Waves and Their Interaction with Resonant Electrons during High-velocity Bulk Flows in the Earth’s Magnetotail

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