Heating and acceleration of charged particles during magnetic dipolarizations
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In this paper, we analyzed the thermal and energy characteristics of the plasma components observed during the magnetic dipolarizations in the near tail by the Cluster satellites. It was previously found that the first dipolarization the ratio of proton and electron temperatures (T p/T e) was ~6–7. At the time of the observation of the first dipolarization front T p/T e decreases by up to ~3–4. The minimum value T p/T e (~2.0) is observed behind the front during the turbulent dipolarization phase. Decreases in T p/T e observed at this time are associated with an increase in T e, whereas the proton temperature either decreases or remains unchanged. Decreases of the value T p/T e during the magnetic dipolarizations coincide with increase in wave activity in the wide frequency band up to electron gyrofrequency f ce. High-frequency modes can resonantly interact with electrons causing their heating. The acceleration of ions with different masses up to energies of several hundred kiloelectron-volts is also observed during dipolarizations. In this case, the index of the energy spectrum decreases (a fraction of energetic ions increases) during the enhancement of low-frequency electromagnetic fluctuations at frequencies that correspond to the gyrofrequency of this ion component. Thus, we can conclude that the processes of the interaction between waves and particles play an important role in increasing the energy of plasma particles during magnetic dipolarizations.
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- 9.Zhou, M., Ashour-Abdalla, M., Deng, X., et al., THEMIS observation of multiple dipolarization fronts and associated wave characteristics in the near- Earth magnetotail, Geophys. Res. Lett., 2009, vol. 36, L20107. doi 10.1029/2009GL040663Google Scholar
- 11.Wang, C.-P., Gkioulidou, M., Lyons, L.R., and Angelopoulos, V., Spatial distributions of the ion to electron temperature ratio in the magnetosheath and plasma sheet, J. Geophys. Res., 2012, vol. 117, A08215. doi 10.1029/2012JA017658Google Scholar
- 21.Daly, P.W. and Kronberg, E.A., User guide to the RAPID measurements in the Cluster Active Archive (CAA), Tech. Rep. CAA-EST-UG-RAP, Paris, European Space Agency, 2015.Google Scholar
- 23.Fu, H.S., Khotyaintsev, Y.V., André, M., and Vaivads, A., Fermi and betatron acceleration of suprathermal electrons behind dipolarization fronts, Geophys. Res. Lett., 2011, vol. 38, L16104. doi 10.1029/2011GL048528Google Scholar