Steepening of kinetic magnetosonic waves into shocklets: Simulations and consequences for planetary shocks and comets

Journal Article · Thu Mar 01 04:00:00 EST 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA095iA03p02281· OSTI ID:5223156

Omidi, N ^[1]; Winske, D ^[2]

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1. Univ. of California, San Diego, La Jolla (United States)
2. Los Alamos National Lab., NM (United States)

Numerical simulations are used to investigate the nonlinear evolution of oblique low-frequency electromagnetic (kiinetic magnetosonic) waves, which have been observed upstream of planetary bow shocks and at comet Giacobini-Zinner. The observations show that the waves are elliptically polarized and have a sinusoidal form when their amplitude is small, but they become steepend and linearly polarized as they grow in amplitude. These waves have been referred to as shocklets. A high-frequency whisterl wave packet is commonly seen at the steepened edge of the shocklets. To investigate the generation and the nonlinear evolution of kinetic magnetosonic waves in a self-consistent manner, an electromagnetic hybrid code (particle ions, fluid electrons) is used in two stages. In the first stage, a large nonperiodic box is utilized to generate a series of small-amplitude waves, one of which is then isolated for the second stage of the simulations, in which much higher resolution is employed to investigate further growth and the nonlinear evolution of the isolated wave. The results show that the original small-amplitude elliptically polarized wave grows and steepens, such that its polarization changes and becomes somewhat linear. The steepening process is associated with the coherent generation of a broad spectrum of waves on the magnetosonic whistler branch, which propagate at various phase and group velocities. As a result, the waveform spreads in space, causing the change in polarization.

• OSTI ID: 5223156
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:A3; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AMPLITUDES
COMETS
COMPUTERIZED SIMULATION
ELECTROMAGNETIC RADIATION
HYDROMAGNETIC WAVES
INTERACTIONS
MACH NUMBER
MAGNETOACOUSTIC WAVES
NOISE
NONLINEAR PROBLEMS
PLANETS
RADIATIONS
RADIO NOISE
RADIOWAVE RADIATION
SHOCK WAVES
SIMULATION
SOLAR ACTIVITY
SOLAR WIND
VELOCITY
WAVE PACKETS
WHISTLERS