The electron forewake: Shadowing and drift-energization as flowing magnetized plasma encounters an obstacle
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Hutchinson_The electron forewake.pdf
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21.06 MB
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Author(s)
Haakonsen, Christian Bernt
Hutchinson, Ian Horner
Date Issued
October 2015
Journal
Physics of Plasmas
Publisher
American Institute of Physics (AIP)
Citation
Haakonsen, Christian Bernt, and Ian H. Hutchinson. “The Electron Forewake: Shadowing and Drift-Energization as Flowing Magnetized Plasma Encounters an Obstacle.” Physics of Plasmas 22.10 (2015): 102103.
Version
Original manuscript
Abstract
Flow of magnetized plasma past an obstacle creates a traditional wake, but also a forewake region arising from shadowing of electrons. The electron forewakes resulting from supersonic flows past insulating and floating-potential obstacles are explored with 2D electrostatic particle-in-cell simulations, using a physical ion to electron mass ratio. Drift-energization is discovered to give rise to modifications to the electron velocitydistribution,
including a slope-reversal, providing a novel drive of forewake instability. The slope-reversal is present at certain locations in all the simulations, and appears to be quite robustly generated. Wings of enhanced electron density are observed in some of the simulations, also associated with drift-energization. In the simulations with a floating-potential obstacle, the specific potential structure behind that obstacle allows fast electrons to cross the wake, giving rise to a more traditional shadowing-driven two-stream instability. Fluctuations associated with such instability are observed in the simulations, but this instability-mechanism is expected to be more sensitive to the plasma parameters than that associated with the slope-reversal.
MIT Department
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
Massachusetts Institute of Technology. Plasma Science and Fusion Center
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Creative Commons Attribution-Noncommercial-Share Alike
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DOI of Published Version
https://doi.org/10.1063/1.4932006
