Formation of the wave compressional boundary in the earth's foreshock

Journal Article · Sat Oct 01 04:00:00 EDT 1988 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA093iA10p11354· OSTI ID:5876968

Skadron, G; Holdaway, R D ^[1]; Lee, M A ^[2]

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1. Illinois State Univ., Normal (United States)
2. Univ. of New Hampshire, Durham (United States)

The authors analyze the interaction between energetic protons and hydromagnetic waves in the Earth's ion foreshock and locate compressional wave boundaries corresponding to interplanetary magnetic field (IMF) inclinations to the solar wind of {theta}{sub BV} equal to 45{degree} and 25{degree}. Protons injected into the solar wind at the bow shock interact with MHD waves traveling along the IMF lines intersecting the shock. Starting with the quasi-linear pitch angle diffusion equation, they obtain fluid equations for the densities and mean velocities of outward and inward streaming energetic protons. The excitation and damping of waves by these protons are described by linear growth rates for parallel propagation and evaluated using a model proton distribution function controlled by the local fluid variables. The coupled equations for the evolution of the wave intensities, proton densities, and mean velocities are solved numerically assuming a prescribed proton injection rate at the shock. They find that in the solar wind frame, (1) the dominant wave-particle interaction in the outer foreshock is the damping of inward propagating (toward the shock) left-polarized waves, producing a magnetically quiet region immediately downstream of the foreshock boundary; (2) excitation of outward propagating right-polarized waves farther downstream leads to the recovery of {delta}{vert bar}B{vert bar} and to an upstream boundary for enhanced compressional wave activity; (3) at {theta}{sub BV} = 45{degree}, the calculated compressional boundary has a mean inclination of 78{degree} from the Earth-Sun axis, compared with the observed range of 85{degree} {plus minus} 3{degree}.

• OSTI ID: 5876968
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Journal Issue: A10 Vol. 93:A10; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BARYONS
CHARGED PARTICLES
COLLISIONLESS PLASMA
COMPRESSION
DATA ANALYSIS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HYDROMAGNETIC WAVES
INTERACTIONS
INTERPLANETARY MAGNETIC FIELDS
ION DENSITY
IONS
MAGNETIC FIELDS
NUCLEONS
PLASMA
PLASMA DENSITY
PROTONS
QUASILINEAR PROBLEMS
REFLECTION
SHOCK WAVES
SOLAR ACTIVITY
SOLAR WIND
WAVE PROPAGATION