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Abstract Magnetic reconnection is a fundamental process in space and astrophysical plasmas that converts magnetic energy to particle energy. Recently, a novel kind of reconnection, called electron-only reconnection, has been observed in Earth's magnetosheath plasma. A defining characteristic of electron-only reconnection is that electron jets are observed but ion jets are absent. This is in contrast with traditional ion-coupled reconnection, where both ions and electrons exhibit outflowing velocity jets. Findings from the Magnetospheric Multiscale mission observations and particle-in-cell simulations show clear signatures of electron heating in electron-only reconnection events, while ions are not heated or cooled in these events. This result is unlike ion-coupled reconnection, where both ions and electrons are heated to varying degrees. The ratio of electron to ion dissipation increases with the local magnetic curvature, indicating that the partition of heat into ions and electrons is dependent on the current-sheet thickness.
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Phase-space Analysis of Ordered and Disordered Nonthermal Ion Energization during Magnetic Reconnection
Abstract Anomalous ion heating is frequently observed to accompany magnetic reconnection, yet there is little consensus on its origin. Instead of the usual velocity-space analysis, we use phase-space analysis to exhaustively explain how ions are nonthermally energized during collisionless, antiparallel magnetic reconnection. There are both ordered and disordered aspects in the process; the former is explained in terms of conservative quantities, and the latter is explained by demonstrating chaos through a direct calculation of Lyapunov exponents. The former induces “multibeam-like heating” in all three directions, whereas the latter induces stochastic bulk heating. Profiles of the ion temperature tensor components during reconnection can be easily understood by the phase-space distributions of ions in different motional stages.
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- Award ID(s):
- 2105492
- PAR ID:
- 10468883
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 956
- Issue:
- 2
- ISSN:
- 0004-637X
- Format(s):
- Medium: X Size: Article No. 105
- Size(s):
- Article No. 105
- Sponsoring Org:
- National Science Foundation
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