The Alfvén edge in asymmetric reconnection
We show that in the case of magnetic reconnection where the Alfvén velocity is much higher in the plasma on one side of the current sheet than the other, an Alfvén edge is formed. This edge is located between the electron and ion edges on the high Alfvén velocity side of the current sheet. The A...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2010-06-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/28/1327/2010/angeo-28-1327-2010.pdf |
| Summary: | We show that in the case of magnetic reconnection where the Alfvén
velocity is much higher in the plasma on one side of the current sheet than
the other, an Alfvén edge is formed. This edge is located between the
electron and ion edges on the high Alfvén velocity side of the current
sheet. The Alfvén edge forms because the Alfvén wave generated near the
X-line will propagate faster than the accelerated ions forming the ion edge.
We discuss possible generation mechanism and the polarization of the Alfvén
wave in the case when higher Alfvén speed is due to larger magnetic field
and smaller plasma density, as in the case of magnetopause reconnection. The
Alfvén wave can be generated due to Hall dynamics near the X-line. The
Alfvén wave pulse has a unipolar electric field and the parallel current
will be such that the outer current on the high magnetic field side is
flowing away from the X-line. Understanding Alfvén edges is important for
understanding the separatrix regions at the boundaries of reconnection jets.
We present an example of Alfvén edge observed by the Cluster spacecraft at
the magnetopause. |
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| ISSN: | 0992-7689 1432-0576 |