Cold ion heating at the low-latitude magnetopause during magnetic reconnection

Friday, 18 December 2015: 10:35
2009 (Moscone West)
Sergio Toledo Redondo1,2, Mats Andre2, Andris Vaivads2, Yuri V Khotyaintsev2, Benoit Lavraud3, Andrey V Divin4, Nicolas Aunai5 and Daniel Bruce Graham2, (1)European Space Agency, SRE-ODS, Villanueva De La CaƱada, Spain, Spain, (2)IRF Swedish Institute of Space Physics Uppsala, Uppsala, Sweden, (3)IRAP, Toulouse, France, (4)Swedish Inst of Space Physics, Uppsala, Sweden, (5)Laboratoire de Physique des Plasmas (UMR7648), CNRS/Ecole Polytechnique/UPMC/Univ. Paris Sud/Obs. de Paris, Paris, France
It has been recently shown that cold ions (energies up to tens of eV) of ionospheric origin are present in the magnetosphere and they can reach the magnetopause, entraining magnetic reconnection. They are of particular importance at low-latitudes where they can dominate over the hot magnetospheric ions (tens of keV). Cold ions have smaller gyroradius, and therefore they remain magnetized down to smaller spatial scales than the hot ions, introducing a new length-scale into the reconnection process. The Cluster orbit crossed the subsolar magnetopause region several times during 2007 and 2008. We observe cold ions ExB drifting with the strong E fields set up during reconnection in many of these crossings. At the same time, the cold ions are heated when convecting towards the exhausts. We investigate the heating mechanisms of the cold ions using two spacecraft, to distinguish spatial and time variations of the E fields.