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Title: High‐Frequency Plasma Waves and Pitch Angle Scattering Induced by Pulsed Electron Beams

Abstract

Cherenkov radiation from a pulse of charge propagating along the magnetic field in a magnetized plasma is analyzed using theory and fluid–kinetic simulations. Besides radiation into whistler modes, the subject of many previous investigations in laboratory and space, radiation can occur through extraordinary (X) modes. Theory and simulations demonstrate that X mode radiation efficiencies can be orders of magnitude higher than those into whistler modes. Test particle simulations of the dynamics of energetic electrons in the beam–generated wavefield show that X modes can also induce pitch angle scattering much more efficiently than whistlers. While coherence effects associated with spreading of realistic beam pulses may limit the size of the X mode source region, a simple model of beam dynamics suggests that the size of this region could be substantial (hundreds of meters for ionospheric conditions). Furthermore, these results have potentially important implications for many problems, including understanding losses in the near–Earth environment and radiation belt remediation.

Authors:
ORCiD logo [1]; ORCiD logo [2]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Space Science Inst., Boulder, CO (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
1569612
Alternate Identifier(s):
OSTI ID: 1561408
Report Number(s):
LA-UR-17-30198
Journal ID: ISSN 2169-9380
Grant/Contract Number:  
89233218CNA000001; 20170423ER
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Space Physics
Additional Journal Information:
Journal Name: Journal of Geophysical Research. Space Physics; Journal ID: ISSN 2169-9380
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; electron beams; Cherenkov radiation; whistler waves; R‐X waves; pitch angle scattering

Citation Formats

Delzanno, Gian Luca, and Roytershteyn, Vadim. High‐Frequency Plasma Waves and Pitch Angle Scattering Induced by Pulsed Electron Beams. United States: N. p., 2019. Web. doi:10.1029/2019JA027046.
Delzanno, Gian Luca, & Roytershteyn, Vadim. High‐Frequency Plasma Waves and Pitch Angle Scattering Induced by Pulsed Electron Beams. United States. doi:10.1029/2019JA027046.
Delzanno, Gian Luca, and Roytershteyn, Vadim. Sat . "High‐Frequency Plasma Waves and Pitch Angle Scattering Induced by Pulsed Electron Beams". United States. doi:10.1029/2019JA027046.
@article{osti_1569612,
title = {High‐Frequency Plasma Waves and Pitch Angle Scattering Induced by Pulsed Electron Beams},
author = {Delzanno, Gian Luca and Roytershteyn, Vadim},
abstractNote = {Cherenkov radiation from a pulse of charge propagating along the magnetic field in a magnetized plasma is analyzed using theory and fluid–kinetic simulations. Besides radiation into whistler modes, the subject of many previous investigations in laboratory and space, radiation can occur through extraordinary (X) modes. Theory and simulations demonstrate that X mode radiation efficiencies can be orders of magnitude higher than those into whistler modes. Test particle simulations of the dynamics of energetic electrons in the beam–generated wavefield show that X modes can also induce pitch angle scattering much more efficiently than whistlers. While coherence effects associated with spreading of realistic beam pulses may limit the size of the X mode source region, a simple model of beam dynamics suggests that the size of this region could be substantial (hundreds of meters for ionospheric conditions). Furthermore, these results have potentially important implications for many problems, including understanding losses in the near–Earth environment and radiation belt remediation.},
doi = {10.1029/2019JA027046},
journal = {Journal of Geophysical Research. Space Physics},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {9}
}

Journal Article:
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This content will become publicly available on September 7, 2020
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