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Title: Evolution of ion distributions across the nearly perpendicular bow shock: specularly and non-specularly reflected-gyrating ions

Abstract

Ion velocity space distributions measured with Los Alamos/Garching instruments on ISEE 1 and 2 across the earth's bow shock have revealed that the nearly perpendicular shock reflects some fraction of the incident solar wind ions over a wide range of Mach numbers (M/sub A/approx. =2.0-12.4). The relative density of the reflected ions varies from 1-3% of the solar wind density at M/sub A/roughly-equal2 to 15-25% at M/sub A/ = 8-12, in qualitative agreement with computer simulations and with predictions that indicate that such ions are needed to provide essential dissipation at the shock. These ions gyrate about B in the plasma rest frame with a speed of approx.2 v/sub i/n, where r/sub i/n is the normal component of the solar wind flow, and their density increases by approx.2 orders of magnitude at the foward end of the ''foot'' of the shock profile approx.0.7 ion gyroradii upstream from the shock ramp. This is substantial evidence that the bulk of these ions have been reflected at the shock in a nearly specular fashion. Depending on the shock geometry, some low numbers of reflected-gyrating ions are sometimes observed a few gyroradii ahead of the outer edge of the foot. Model calculations suggest thatmore » these additional ions are produced by non-specular reflection of a much smaller fraction of the incident solar wind. Downstream of the shock ramp, the secondary ions gyrate with a slightly higher speed, v/sub g/roughly-equal2.15 v/sub i/n, in the downstream rest frame. Individual groups of gyrating ions rapidly disperse in velocity space to form a high-energy torus centered at the bulk velocity of the distributions.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Max-Planck-Institut fuer Physik und Astrophysik, Institut fuer Extraterrestriche Physik, 8046 Garching, Federal Republic of Germany
OSTI Identifier:
5470530
Resource Type:
Journal Article
Journal Name:
J. Geophys. Res.; (United States)
Additional Journal Information:
Journal Volume: 88:A8
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; MAGNETOSPHERE; SHOCK WAVES; SOLAR WIND; BACKSCATTERING; COMPUTERIZED SIMULATION; DISTRIBUTION FUNCTIONS; INTERPLANETARY MAGNETIC FIELDS; INTERPLANETARY SPACE; ION DENSITY; MACH NUMBER; REFLECTION; EARTH ATMOSPHERE; FUNCTIONS; MAGNETIC FIELDS; SCATTERING; SIMULATION; SOLAR ACTIVITY; SPACE; VELOCITY; 640203* - Atmospheric Physics- Magnetospheric Phenomena- (-1987)

Citation Formats

Sckopke, N, Paschmann, G, Bame, S J, Gosling, J T, and Russell, C T. Evolution of ion distributions across the nearly perpendicular bow shock: specularly and non-specularly reflected-gyrating ions. United States: N. p., 1983. Web. doi:10.1029/JA088iA08p06121.
Sckopke, N, Paschmann, G, Bame, S J, Gosling, J T, & Russell, C T. Evolution of ion distributions across the nearly perpendicular bow shock: specularly and non-specularly reflected-gyrating ions. United States. https://doi.org/10.1029/JA088iA08p06121
Sckopke, N, Paschmann, G, Bame, S J, Gosling, J T, and Russell, C T. 1983. "Evolution of ion distributions across the nearly perpendicular bow shock: specularly and non-specularly reflected-gyrating ions". United States. https://doi.org/10.1029/JA088iA08p06121.
@article{osti_5470530,
title = {Evolution of ion distributions across the nearly perpendicular bow shock: specularly and non-specularly reflected-gyrating ions},
author = {Sckopke, N and Paschmann, G and Bame, S J and Gosling, J T and Russell, C T},
abstractNote = {Ion velocity space distributions measured with Los Alamos/Garching instruments on ISEE 1 and 2 across the earth's bow shock have revealed that the nearly perpendicular shock reflects some fraction of the incident solar wind ions over a wide range of Mach numbers (M/sub A/approx. =2.0-12.4). The relative density of the reflected ions varies from 1-3% of the solar wind density at M/sub A/roughly-equal2 to 15-25% at M/sub A/ = 8-12, in qualitative agreement with computer simulations and with predictions that indicate that such ions are needed to provide essential dissipation at the shock. These ions gyrate about B in the plasma rest frame with a speed of approx.2 v/sub i/n, where r/sub i/n is the normal component of the solar wind flow, and their density increases by approx.2 orders of magnitude at the foward end of the ''foot'' of the shock profile approx.0.7 ion gyroradii upstream from the shock ramp. This is substantial evidence that the bulk of these ions have been reflected at the shock in a nearly specular fashion. Depending on the shock geometry, some low numbers of reflected-gyrating ions are sometimes observed a few gyroradii ahead of the outer edge of the foot. Model calculations suggest that these additional ions are produced by non-specular reflection of a much smaller fraction of the incident solar wind. Downstream of the shock ramp, the secondary ions gyrate with a slightly higher speed, v/sub g/roughly-equal2.15 v/sub i/n, in the downstream rest frame. Individual groups of gyrating ions rapidly disperse in velocity space to form a high-energy torus centered at the bulk velocity of the distributions.},
doi = {10.1029/JA088iA08p06121},
url = {https://www.osti.gov/biblio/5470530}, journal = {J. Geophys. Res.; (United States)},
number = ,
volume = 88:A8,
place = {United States},
year = {Mon Aug 01 00:00:00 EDT 1983},
month = {Mon Aug 01 00:00:00 EDT 1983}
}