Earth's bow shock: tests of MHD predictions, and the occurrence of downstream ion-cyclotron waves at high Alfven Mach numbers and high plasma betas

Thesis/Dissertation · Thu Jan 01 00:00:00 EST 1987

OSTI ID:7128675

Winterhalter, D

The author examined 204 bow shock crossings observed in the magnetic field and plasma data on ISEE-1. Using the measured upstream field and plasma data the calculated the downstream field magnitudes by using the single-fluid MHD Rankine-Hugoniot jump conditions, and compared the result with the observed downstream field magnitudes. The simple MHD model approach can predict the down-stream field magnitude only on the average, but does so quite well if: (1) A polytropic index of approximately 53 is used in the calculations. (2) The angle between the upstream field and the shock normal is greater than 45/sup 0/. (3) The Alfven Mach number is less than about 10. For angles less than 45/sup 0/, and in particular at 45/sup 0/, the predictions overestimate the observed field strength. For M/sub A/ > 10, the predictions underestimate the observations. Further observations of the bow shock show that in the higher Mach number regime, where the observed downstream field magnitudes differ from the Rankin-Hugoniot predictions, large-amplitude periodic structures are present immediately downstream of the magnetic field ramp.

• Research Organization: California Univ., Los Angeles (USA)
• OSTI ID: 7128675
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
EARTH MAGNETOSPHERE
PLASMA WAVES
HIGH-BETA PLASMA
MACH NUMBER
MAGNETOHYDRODYNAMICS
RANKINE-HUGONIOT EQUATIONS
EARTH ATMOSPHERE
EQUATIONS
FLUID MECHANICS
HYDRODYNAMICS
MECHANICS
PLASMA
VELOCITY
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena