Low Mach number parallel and quasi-parallel shocks

Journal Article · Sat Dec 01 00:00:00 EST 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA095iA12p20717· OSTI ID:5310589

Omidi, N; Quest, K B ^[1]; Winske, D ^[2]

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1. Univ. of California, La Jolla (USA)
2. Los Alamos National Lab., NM (USA)

The structure of low Mach number parallel and quasi-parallel shocks is investigated by using a one-dimensional electromagnetic hybrid code. It is shown that both structure of an ion dissipation at these shocks can be divided into two distinct regimes. In the parallel limit, the shock consists of large amplitude electromagnetic waves on the magnetosonic-whistler branch. The amount of ion heating and scattering by these waves is shown to be minimal, and as a result the shock does not decouple from the piston. Instead, the required hotter downstream ion distribution function is formed by the superposition of two distinct populations of incident and piston reflected ions. This distribution function is shown to be unstable near the shock transition region, maintaining the magnetosonic-whistler waves, but is stable further downstream. The structure of quasi-parallel shocks is found to be considerably different. Initially, the shock consists of phase standing dispersive whistlers in the upstream, whose last cycle constitutes the shock ramp. These waves make little or no contribution to ion heating. At later times, a longer wavelength whistler wave packet is formed upstream of the shock. These waves are shown to be excited by the backstreaming (reflected or leaked) ions via the electromagnetic ion beam instability. Unlike the phase standing whistlers, these waves result in considerable local deceleration and heating of the solar wind plasma. As a result, the transition from upstream to downstream plasma is not monotonic but rather, it occurs in an intermittent fashion.

• OSTI ID: 5310589
• Journal Information: Journal of Geophysical Research; (United States), Vol. 95:A12; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
EARTH MAGNETOSPHERE
SOLAR WIND
SHOCK WAVES
COMPUTERIZED SIMULATION
ACCELERATION
INTERACTIONS
PLASMA HEATING
COMPUTER CODES
ENERGY LOSSES
HEATING
INSTABILITY
IONS
MACH NUMBER
WAVE PACKETS
WHISTLERS
CHARGED PARTICLES
EARTH ATMOSPHERE
ELECTROMAGNETIC RADIATION
LOSSES
NOISE
RADIATIONS
RADIO NOISE
RADIOWAVE RADIATION
SIMULATION
SOLAR ACTIVITY
VELOCITY
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena
640104 - Astrophysics & Cosmology- Solar Phenomena