Non-Maxwellianity of electron distributions and their source regions
Abstract
Identifying regions where electron distributions strongly deviate from Maxwellian distributions and understanding the basic physical processes driving this deviation are of crucial importance in space plasma physics. These are the regions where kinetic plasma process can strongly affect the large-scale plasma properties and dynamics. Examples where non-Maxwellianity occurs include reconnection diffusion regions, shocks, turbulence, and current sheets. Using the Magnetospheric Multiscale (MMS) spacecraft, we evaluate and quantify the deviations of electron distributions from bi-Maxwellian distribution functions predicted from electron moments. A statistical survey shows that the non-Maxwellianity tends to scale inversely with number density, due to the counting statistics of the particle detectors. However, we show that large deviations from the statistical medians can be used to identity regions of enhanced non-Maxwellianity. Electron non-Maxwellianity is routinely observed at the bowshock, turbulent magnetosheath, and in magnetic reconnection diffusion regions and outflows regions. We discuss how enhanced non-Maxwellianity develops, and its relation to ongoing turbulence.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSH11B..05G
- Keywords:
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- 2134 Interplanetary magnetic fields;
- INTERPLANETARY PHYSICS;
- 2159 Plasma waves and turbulence;
- INTERPLANETARY PHYSICS;
- 2164 Solar wind plasma;
- INTERPLANETARY PHYSICS;
- 4415 Cascades;
- NONLINEAR GEOPHYSICS