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| Titel |
Electron heating and Tp/Te variations during magnetic dipolarizations |
| VerfasserIn |
Elena Grigorenko, Elena Kronberg, Patrick Daly, Natalia Ganushkina, Benoit Lavraud, Jean-André Sauvaud, Lev Zelenyi |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250141181
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| Publikation (Nr.) |
 EGU/EGU2017-4657.pdf |
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| Zusammenfassung |
| The proton-to-electron temperature ratio (Tp/Te) in the plasma sheet (PS) of the Earth’s magnetotail is studied by using 5 years of Cluster observations (2001–2005). The PS intervals are searched within a region defined with -19<X≤-7Re and |Y|<15Re (GSM) under the condition |Bx|≤10nT and 160 intervals were selected. In many PS intervals from our data base Tp/Te varies over a wide range from a few units to several tens of units. In 86 PS intervals the Tp/Te decreases below 3.5. In the majority of these intervals the Tp/Te drops are observed during magnetotail dipolarizations. A superposed epoch analysis applied to these events shows that the minimum value of Tp/Te is observed after the dipolarization onset during the “turbulent phase” of dipolarization, when a number of transient Bz pulses are reduced, but the value of Bz field is still large and an intensification of wave activity is observed. The Tp/Te drops and associated increases of Te often coincide either with bursts of broadband electrostatic emissions, which may include electron cyclotron harmonics, or with broadband electromagnetic emission in a frequency range from proton plasma frequency (fpp) up to the electron gyrofrequency (fce). These findings show that the wave activity developing in the current sheet after dipolarization onset may play a role in the additional electron heating and the associated Tp/Te decrease.
This work was supported by the Volskwagen Foundation (grant Az 90 312). |
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