Zhang, YC;
Shen, C;
Marchaudon, A;
Rong, ZJ;
Lavraud, B;
Fazakerley, A;
Yao, Z;
... Liu, ZX; + view all
(2016)
First in situ evidence of electron pitch angle scattering due to magnetic field line curvature in the Ion diffusion region.
Journal of Geophysical Research: Space Physics
, 121
(5)
pp. 4103-4110.
10.1002/2016JA022409.
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Abstract
Theory predicts that the first adiabatic invariant of a charged particle may be violated in a region of highly curved field lines, leading to significant pitch angle scattering for particles whose gyroradius are comparable to the radius of the magnetic field line curvature. This scattering generates more isotropic particle distribution functions, with important impacts on the presence or absence of plasma instabilities. Using magnetic curvature analysis based on multipoint Cluster spacecraft observations, we present the first investigation of magnetic curvature in the vicinity of an ion diffusion region where reconnected field lines are highly curved. Electrons at energies > 8 keV show a clear pitch angle ordering between bidirectional and trapped distribution in surrounding regions, while we show that in the more central part of the ion diffusion region electrons above such energies become isotropic. By contrast, colder electrons ( 1 keV) retain their bidirectional character throughout the diffusion regions. The calculated adiabatic parameter K2 for these electrons is in agreement with theory. This study provides the first observational evidence for particle pitch angle scattering due to magnetic field lines with well characterized curvature in a space plasma.
| Type: | Article |
|---|---|
| Title: | First in situ evidence of electron pitch angle scattering due to magnetic field line curvature in the Ion diffusion region |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1002/2016JA022409 |
| Publisher version: | http://dx.doi.org/10.1002/2016JA022409 |
| Language: | English |
| Additional information: | ©2016. American Geophysical Union. All Rights Reserved. |
| Keywords: | Plasma sheet, Magnetic reconnection, Charged particle motion and acceleration, plasma sheet, magnetic reconnection, magnetic curvature, pitch angle scattering |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1492707 |
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