Articles | Volume 29, issue 9
Ann. Geophys., 29, 1571–1579, 2011
https://doi.org/10.5194/angeo-29-1571-2011

Special issue: Cluster 10th anniversary workshop

Ann. Geophys., 29, 1571–1579, 2011
https://doi.org/10.5194/angeo-29-1571-2011

Regular paper 12 Sep 2011

Regular paper | 12 Sep 2011

The proton pressure tensor as a new proxy of the proton decoupling region in collisionless magnetic reconnection

N. Aunai1, A. Retinò1, G. Belmont1, R. Smets1, B. Lavraud3,2, and A. Vaivads4 N. Aunai et al.
  • 1Laboratoire de Physique des Plasmas, UMR 7648, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau, France
  • 2Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse (UPS), France
  • 3Centre National de la Recherche Scientifique, UMR 5277, Toulouse, France
  • 4Swedish Institute of Space Physics, P.O. Box 537, 75121 Uppsala, Sweden

Abstract. Cluster data is analyzed to test the proton pressure tensor variations as a proxy of the proton decoupling region in collisionless magnetic reconnection. The Hall electric potential well created in the proton decoupling region results in bounce trajectories of the protons which appears as a characteristic variation of one of the in-plane off-diagonal components of the proton pressure tensor in this region. The event studied in this paper is found to be consistent with classical Hall field signatures with a possible 20% guide field. Moreover, correlations between this pressure tensor component, magnetic field and bulk flow are proposed and validated, together with the expected counterstreaming proton distribution functions.