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Abstract Electron-only magnetic reconnection was first detected by the Magnetospheric Multiscale (MMS) mission in Earth’s turbulent magnetosheath. Its prevalence in kinetic-scale turbulence has attracted great interest in heliophysics, but also revealed a great challenge in identifying it in turbulence, where electron flows are often complex. The magnetic flux transport (MFT) method is an innovative method to identify active reconnection in numerical simulations and in situ observations of turbulent plasmas. Here we extend this method to distinguish between electron-only and ion-coupled reconnection. The coupling of magnetic field motion with plasma flows in the diffusion regions sets distinct scales in the MFT velocity. While both forms of reconnection satisfy the MFT signature for active reconnection as MFT inflows and outflows at an X-line, the specific electron-only MFT signature is only an electron-scale MFT outflow along the current sheet normal direction, whereas the specific ion-coupled signature is a two-scale, outer-ion-and-inner-electron-scale MFT outflow in the electron diffusion region, which evolves into a single ion-scale in the ion diffusion region. These signatures are verified in a simulation of gyrokinetic turbulence. The dependence of the MFT outflow on the distance downstream from the X-lines also agrees well with the framework of magnetic field–plasma flow coupling. The new MFT signatures provide a clear and reliable tool for investigating electron-only reconnection in turbulence, independent of the development of electron outflows. They are directly applicable to kinetic and fluid simulations, and have potential application to observations of diffusion region crossings by spacecraft missions such as MMS.
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This content will become publicly available on October 1, 2026
Investigation of the Diffusion Region With Varying Turbulence Intensities Around the X‐Line of Magnetotail Reconnection
Abstract Magnetic reconnection and turbulence are two fundamental processes in space plasma environments. They are intricately coupled, driving energy transfer and conversion. Despite significant research efforts, the development of turbulence within the reconnection diffusion region and its impact on the reconnection process remain open questions. In this study, we analyze 16 magnetotail reconnection cases observed by the Magnetospheric Multiscale (MMS) mission, focusing on the diffusion regions in the vicinity of the X‐line. We find that turbulence tends to be stronger in diffusion regions with lower plasma density and plasma beta. Turbulence can enhance the electron energization process in the diffusion region primarily through electron heating. As turbulence intensifies, the continuous current layer of the diffusion region breaks into fragmented currents, suggesting a transition from laminar to turbulent reconnection. Moreover, spectral breaks between ion and electron cyclotron frequencies are consistently observed in magnetic and electric field fluctuations within reconnecting current sheets, suggesting that such breaks may be a characteristic feature of the reconnection process. These findings provide valuable insights into the development and role of turbulence within the reconnection diffusion region.
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- Award ID(s):
- 2438328
- PAR ID:
- 10700758
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Space Physics
- Volume:
- 130
- Issue:
- 10
- ISSN:
- 2169-9380
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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