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Title: Survey of coherent ion reflection at the quasi-parallel bow shock

Abstract

Ions coherently reflected off the Earth's bow shock have previously been observed both when the upstream geometry is quasi-perpendicular and when it is quasi-parallel. In the case of quasiperpendicular geometry, the ions are reflected in a nearly specular manner and are quickly carried back into the shock by the convecting magnetic field. In the quasi-parallel geometry, however, near-specularly reflected ions' guiding center velocities would on the average be directed away from the shock, allowing the ions to escape into the upstream region. The conditions under which coherent reflection occurs and the subsequent coupling of the reflected ions to the incoming solar wind plasma are important factors when assessing the contribution of the reflected ions to the downstream temperature increase and the shock structure. The survey presented in this paper, along with previously reported observations, suggests that near-specularly reflected ions are indeed an important aspect of energy dissipation at the Earth's quasi-parallel bow shock. The authors find that (1) cool, coherent, near-specularly reflected ion beams are detected over nearly the full range of upstream plasma paraameters commonly found at the Earth's bow shock; (2) the beams are typically observed only near the shock ramp or some shock-like feature; and (3) themore » observed beam velocities are almost always consistent with what one would expect for near-specularly reflected ions after only a small fraction of a gyroperiod following reflection. The second and third points indicate that the beams spread very quickly in velocity space. This spread in velocities could be due either to interactions between the beam and incoming solar wind ions or to some initially small velocity spread in the beam.« less

Authors:
; ; ;  [1];  [2]
  1. Los Alamos National Lab., NM (United States)
  2. Univ. of California, Los Angeles (United States)
Publication Date:
OSTI Identifier:
5222159
Resource Type:
Journal Article
Journal Name:
Journal of Geophysical Research; (United States)
Additional Journal Information:
Journal Volume: 95:A3; Journal ID: ISSN 0148-0227
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; EARTH MAGNETOSPHERE; SOLAR WIND; IONS; REFLECTION; INTERACTIONS; COMPUTERIZED SIMULATION; ENERGY LOSSES; GEOMETRY; GUIDING-CENTER APPROXIMATION; ION BEAMS; ORIENTATION; SHOCK WAVES; BEAMS; CHARGED PARTICLES; EARTH ATMOSPHERE; LOSSES; MATHEMATICS; SIMULATION; SOLAR ACTIVITY; 640201* - Atmospheric Physics- Auroral, Ionospheric, & Magetospheric Phenomena

Citation Formats

Onsager, T G, Thomsen, M F, Gosling, J T, Bame, S J, and Russell, C T. Survey of coherent ion reflection at the quasi-parallel bow shock. United States: N. p., 1990. Web. doi:10.1029/JA095iA03p02261.
Onsager, T G, Thomsen, M F, Gosling, J T, Bame, S J, & Russell, C T. Survey of coherent ion reflection at the quasi-parallel bow shock. United States. https://doi.org/10.1029/JA095iA03p02261
Onsager, T G, Thomsen, M F, Gosling, J T, Bame, S J, and Russell, C T. 1990. "Survey of coherent ion reflection at the quasi-parallel bow shock". United States. https://doi.org/10.1029/JA095iA03p02261.
@article{osti_5222159,
title = {Survey of coherent ion reflection at the quasi-parallel bow shock},
author = {Onsager, T G and Thomsen, M F and Gosling, J T and Bame, S J and Russell, C T},
abstractNote = {Ions coherently reflected off the Earth's bow shock have previously been observed both when the upstream geometry is quasi-perpendicular and when it is quasi-parallel. In the case of quasiperpendicular geometry, the ions are reflected in a nearly specular manner and are quickly carried back into the shock by the convecting magnetic field. In the quasi-parallel geometry, however, near-specularly reflected ions' guiding center velocities would on the average be directed away from the shock, allowing the ions to escape into the upstream region. The conditions under which coherent reflection occurs and the subsequent coupling of the reflected ions to the incoming solar wind plasma are important factors when assessing the contribution of the reflected ions to the downstream temperature increase and the shock structure. The survey presented in this paper, along with previously reported observations, suggests that near-specularly reflected ions are indeed an important aspect of energy dissipation at the Earth's quasi-parallel bow shock. The authors find that (1) cool, coherent, near-specularly reflected ion beams are detected over nearly the full range of upstream plasma paraameters commonly found at the Earth's bow shock; (2) the beams are typically observed only near the shock ramp or some shock-like feature; and (3) the observed beam velocities are almost always consistent with what one would expect for near-specularly reflected ions after only a small fraction of a gyroperiod following reflection. The second and third points indicate that the beams spread very quickly in velocity space. This spread in velocities could be due either to interactions between the beam and incoming solar wind ions or to some initially small velocity spread in the beam.},
doi = {10.1029/JA095iA03p02261},
url = {https://www.osti.gov/biblio/5222159}, journal = {Journal of Geophysical Research; (United States)},
issn = {0148-0227},
number = ,
volume = 95:A3,
place = {United States},
year = {Thu Mar 01 00:00:00 EST 1990},
month = {Thu Mar 01 00:00:00 EST 1990}
}