Publication Date:
2016-06-09
Description:
Dipolarization fronts (DFs), embedded in bursty bulk flows (BBFs), play a crucial role in Earth's plasmasheet dynamics because the energy input from the solar wind is partly dissipated in their vicinity. This dissipation is in the form of strong low-frequency waves that can heat and accelerate energetic electrons up to the high latitude plasmasheet. However, the dynamics of DF propagation and associated low-frequency waves in the magnetotail are still under debate due to instrumental limitations and spacecraft separation distances. In May 2015 the Magnetospheric Multiscale (MMS) mission was in a string-of-pearls configuration with an average inter-satellite distance of 160 km, which allows us to study in detail the microphysics of DFs. Thus in this letter we employ MMS data to investigate the properties of dipolarization fronts propagating earthward and associated whistler-mode wave emissions. We show that the spatial dynamics of DFs are below the ion gyroradius scale in this region (∼500 km), which can modify the dynamics of energetic ions ahead of the DF (e.g. making their motion non-adiabatic). We also show that whistler-wave dynamics have a temporal scale of the order of the ion gyroperiod (a few seconds), indicating that the perpendicular temperature anisotropy can vary on such time scales.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics
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