Fundamental Understanding of Magnetic Reconnection via Spiral CT Scan. IX. Statistics of Ion Velocity and Electron Velocity
- 1Beihang University
- 2Key Laboratory of Space Environment Monitoring and Information Processing
Abstract
For the first time, we identify the characteristic velocity pattern for ions and electrons in all the regions around two-dimensional (2D) X-line by operating a statistical survey of 16 reconnection events based on the spiral CT scan technique. These reconnection events were detected by the MMS mission at Earth’s magnetopause and have been identified as EDR encounters. According to the statistics, we find the electron velocities have distinct features from ion velocities: (1) electron velocities are directed toward X-point in the inflow region and outward X-point in the outflow region at scale above 0.1 d i , corresponding to the electron inflow and outflow; whereas the decoupled ion velocities are very chaotic at such scales. (2) Around the X-line, the electron velocities can be very large. The electrons form an out-of-plane jet near the X-point, field-aligned stream at the magnetosphere-side separatrix region and in the inflow region, with velocities larger than 1000 km s ⁻¹ ; whereas the ion velocities are quite steady and generally below 250 km s ⁻¹ . (3) Both ion velocities and electron velocities are large in the magnetosphere, but small in the magnetosheath. These features reveal the different behaviors between ions and electrons around the X-line, which can significantly improve our understanding of the fundamental physics of the reconnection process. Moreover, the results well agree with classical theory, hence validating our scan technique and normalization method.
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BibTeX
@article{wang2026fundamental,
title = {{Fundamental Understanding of Magnetic Reconnection via Spiral CT Scan. IX. Statistics of Ion Velocity and Electron Velocity}},
author = {Z. Wang and H. S. Fu and J. B. Cao},
journal = {The Astrophysical Journal},
year = {2026},
month = oct,
doi = {10.3847/1538-4357/aea40b},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/aea40b},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Fundamental Understanding of Magnetic Reconnection via Spiral CT Scan. IX. Statistics of Ion Velocity and Electron Velocity
AU - Z. Wang
AU - H. S. Fu
AU - J. B. Cao
PY - 2026
DA - 2026/10/19
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/aea40b
UR - https://iopscience.iop.org/article/10.3847/1538-4357/aea40b
AB - For the first time, we identify the characteristic velocity pattern for ions and electrons in all the regions around two-dimensional (2D) X-line by operating a statistical survey of 16 reconnection events based on the spiral CT scan technique. These reconnection events were detected by the MMS mission at Earth’s magnetopause and have been identified as EDR encounters. According to the statistics, we find the electron velocities have distinct features from ion velocities: (1) electron velocities are directed toward X-point in the inflow region and outward X-point in the outflow region at scale above 0.1 d i , corresponding to the electron inflow and outflow; whereas the decoupled ion velocities are very chaotic at such scales. (2) Around the X-line, the electron velocities can be very large. The electrons form an out-of-plane jet near the X-point, field-aligned stream at the magnetosphere-side separatrix region and in the inflow region, with velocities larger than 1000 km s ⁻¹ ; whereas the ion velocities are quite steady and generally below 250 km s ⁻¹ . (3) Both ion velocities and electron velocities are large in the magnetosphere, but small in the magnetosheath. These features reveal the different behaviors between ions and electrons around the X-line, which can significantly improve our understanding of the fundamental physics of the reconnection process. Moreover, the results well agree with classical theory, hence validating our scan technique and normalization method.
SN - 0004-637X
SN - 1538-4357
ER -