Electron acceleration by parallel and perpendicular electric fields during magnetic reconnection without guide field
- Univ. of Maryland, College Park, MD (United States); NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
- Univ. of New Hampshire, Durham, NH (United States)
- Princeton Univ., NJ (United States)
In this work, electron acceleration due to the electric field parallel to the background magnetic field during magnetic reconnection with no guide field is investigated by theory and two-dimensional electromagnetic particle-in-cell simulations and compared with acceleration due to the electric field perpendicular to the magnetic field. The magnitude of the parallel electric potential shows dependence on the ratio of the plasma frequency to the electron cyclotron frequency as (ωpe/Ωe)-2 and on the background plasma density as N$$^{-½}_{b}$$. In the Earth's magnetotail, the parameter ωpe/Ωe~9 and the background (lobe) density can be of the order of 0.01 cm-3, and it is expected that the parallel electric potential is not large enough to accelerate electrons up to 100 keV. Therefore, we must consider the effect of the perpendicular electric field to account for electron energization in excess of 100 keV in the Earth's magnetotail. Trajectories for high-energy electrons are traced in a simulation to demonstrate that acceleration due to the perpendicular electric field in the diffusion region is the dominant acceleration mechanism, rather than acceleration due to the parallel electric fields in the exhaust regions. For energetic electrons accelerated near the X line due to the perpendicular electric field, pitch angle scattering converts the perpendicular momentum to the parallel momentum. On the other hand, for passing electrons that are mainly accelerated by the parallel electric field, pitch angle scattering converting the parallel momentum to the perpendicular momentum occurs. In this way, particle acceleration and pitch angle scattering will generate heated electrons in the exhaust regions.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)
- Sponsoring Organization:
- USDOE Office of Science (SC); National Science Foundation (NSF); National Aeronautics and Space Administration (NASA)
- Grant/Contract Number:
- AGS-1338944; PHY-0903923; AGS-1202537; AGS-1056898; NNX11AH03G; NNX13AK31G; AGS-1543598; PHY-1229408
- OSTI ID:
- 1565403
- Journal Information:
- Journal of Geophysical Research. Space Physics, Vol. 120, Issue 11; ISSN 2169-9380
- Publisher:
- American Geophysical UnionCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Currents and associated electron scattering and bouncing near the diffusion region at Earth's magnetopause
|
journal | April 2016 |
First in situ evidence of electron pitch angle scattering due to magnetic field line curvature in the Ion diffusion region: Pitch Angle Scattering
|
journal | May 2016 |
Structure of Electron‐Scale Plasma Mixing Along the Dayside Reconnection Separatrix
|
journal | November 2019 |
Electron Acceleration and Thermalization at Magnetotail Separatrices
|
journal | April 2020 |
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