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Lu & Wang 2006
Lu, Q.M. and Wang, S. (2006). Electromagnetic waves downstream of quasi-perpendicular shocks. Journal of Geophysical Research 111: doi: 10.1029/2005JA011319. issn: 0148-0227.

When the incident solar wind H+ and other minor ions cross a shock, they are decelerated differentially by the electrostatic potential at the shock. Therefore ring beam distributions of the minor ions are formed downstream of a quasi-perpendicular shock in the downstream frame. Moreover, the H+ distribution downstream of the quasi-perpendicular shock usually has large perpendicular temperature anisotropy. The He2+ ring beam distribution and H+ temperature anisotropy can excite helium cyclotron waves and proton cyclotron waves, respectively. In this paper, we perform one-dimensional hybrid simulations to investigate the competition between the helium cyclotron waves and proton cyclotron waves, and their influences on the evolution of He2+ and O6+ velocity distributions are also considered. When the wave spectrum is dominated by the helium cyclotron waves, He2+ and O6+ approximately move on the surface of a sphere, which results in shell-like distributions for He2+and O6+. With the increase of the H+ temperature anisotropy T$perp$p/T$parallel$p, the amplitude of the proton cyclotron waves also increases. When it is sufficiently large and comparable with that of the helium cyclotron waves, the motions of He2+ and O6+ are irregular, which results in bi-Maxwellian distributions of He2+and O6+. We also investigate the influence of the plasma ¿$parallel$p on the excited ion cyclotron waves and the evolution of the He2+and O6+ distributions. The simultaneous observations for He2+ and O6+ in the downstream of shocks with Active Magnetospheric Particle Tracer Explorers (AMPTE)/CCE spacecraft have demonstrated their shell-like distributions. The observed results verify the existence of the helium cyclotron waves downstream of supercritical quasi-perpendicular shocks.

BACKGROUND DATA FILES

Abstract

Keywords
Magnetospheric Physics, Magnetosheath, Magnetospheric Physics, Plasma waves and instabilities, Space Plasma Physics, Kinetic waves and instabilities, Space Plasma Physics, Shock waves, Space Plasma Physics, Wave/particle interactions (2483, 6984)
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
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