Magnetic reconnection and cold plasma at the magnetopause

M. André (1) , A. Vaivads (1) , Yuri V. Khotyaintsev (1) , T. Laitinen (1) , H. Nilsson (2) , G. Stenberg (2) , A. Fazakerley (3) , Jean-Gabriel Trotignon (4)

1 IRF - Swedish Institute of Space Physics [Uppsala / Kiruna]
2 IRF - Swedish Institute of Space Physics [Kiruna]
3 MSSL - Mullard Space Science Laboratory
4 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace

We report on detailed observations by the four Cluster spacecraft of magnetic reconnection and a Flux Transfer Event (FTE) at the magnetopause. We detect cold (eV) plasma at the magnetopause with two independent methods. We show that the cold ions can be essential for the electric field normal to the current sheet in the separatrix region at the edge of the FTE and for the associated acceleration of ions from the magnetosphere into the reconnection jet. The cold ions have small enough gyroradii to drift inside the limited separatrix region and the normal electric field can be balanced by this drift, E ≈ −v × B. The separatrix region also includes cold accelerated electrons, as part of the reconnection current circuit.

Domaines: Planète et Univers [physics]

M. André, A. Vaivads, Yuri V. Khotyaintsev, T. Laitinen, H. Nilsson, et al.. Magnetic reconnection and cold plasma at the magnetopause. Geophysical Research Letters, 2010, 37 (22), pp.n/a-n/a. ⟨10.1029/2010GL044611⟩. ⟨insu-03035928⟩