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Electric fields within the martian magnetosphere and ion extraction: ASPERA-3 observations |
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| Authors: | E Dubinin R Lundin J Woch A Fedorov N Krupp M Holmström M Yamauchi J-J Thocaven J Sharber A Coates KS Hsieh H Koskinen P Riihelä T Säles J Luhmann R Cerulli-Irelli M Maggi D Williams P Wurz C Dierker M Carter |
| Institution: | a MPI für Sonnensystemforschung, Max-Planck-Str. 2, D-37191 Katlenburg-Lindau, Germany b Swedish Institute of Space Physics, Box 812, S-98 128 Kiruna, Sweden c Centre d'Etude Spatiale des Rayonnements, BP-4346, F-31028 Toulouse, France d Southwest Research Institute, San Antonio, TX 7228-0510, USA e Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamichara, Japan f Mullard Space Science Laboratory, University College London, Surrey RH5 6NT, UK g University of Arizona, Tucson, AZ 85721, USA h Department of Physical Sciences, University of Helsinki, P.O. Box 64, 00014 Helsinki i Finnish Meteorological Institute, Box 503, FIN-00101 Helsinki, Finland j Space Physics Research Laboratory, University of Michigan, Ann Arbor, MI 48109-2143, USA k Space Science Laboratory, University of California in Berkeley, Berkeley, CA 94720-7450, USA l Space Technology Ireland, National University of Ireland, Maynooth, Co. Kildare, Ireland m Istituto di Fisica dello Spazio Interplanetari, I-00133 Rome, Italy n Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723-6099, USA o Physikalisches Institut, University of Bern, CH-3012 Bern, Switzerland p Technical University of Braunschweig, Hans-Sommer-Strasse 66, D-38106 Braunschweig, Germany q Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, UK |
| Abstract: | Observations made by the ASPERA-3 experiment onboard the Mars Express spacecraft found within the martian magnetosphere beams of planetary ions. In the energy (E/q)-time spectrograms these beams are often displayed as dispersive-like, ascending or descending (whether the spacecraft moves away or approach the planet) structures. A linear dependence between energy gained by the beam ions and the altitude from the planet suggests their acceleration in the electric field. The values of the electric field evaluated from ion energization occur close to the typical values of the interplanetary motional electric field. This suggests an effective penetration of the solar wind electric field deep into the martian magnetosphere or generation of large fields within the magnetosphere. Two different classes of events are found. At the nominal solar wind conditions, a ‘penetration’ occurs near the terminator. At the extreme solar wind conditions, the boundary of the induced magnetosphere moves to a more dense upper atmosphere that leads to a strong scavenging of planetary ions from the dayside regions. |
| Keywords: | Mars Solar wind Magnetospheres Ionospheres Magnetic fields |
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