Long-time evolution of a low-density ion beam

Journal Article · Wed Mar 01 04:00:00 EST 1989 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA094iA03p02443· OSTI ID:6451398

Zachary, A L; Cohen, B I; Max, C E; Arons, J

With a new, orbit-averaged hybrid computer simulation code, we study a cold, fast low-density ion beam which propagates along the ambient magnetic field as it interacts with a much denser fluid background. We examine the character of the interactions as we vary the ion beam density relative to the background density over the range 1 x 10/sup -5/ to 3 x 10/sup -3/. The low beam density simulations may not be directly observable upstream of the Earth's bow shock, but they are included to help develop an understanding of the results seen in the simulations with high-beam density. However, our highest density simulation falls within the range of solar wind data. All the simulations, regardless of the relative beam density, show three distinct phases: (1) an early or ''linear'' phase; (2) an intermediate or ''trapping'' phase; and (3) a late or ''decorrelation'' phase. In the early phase, the beam excites a nearly monochromatic Alfven wave whose amplitude grows exponentially at a rate given by linear perturbation theory. The wave amplitude saturates when the linear growth rate is of the order of the trapping frequency.

• Research Organization: Department of Astronomy and Astrophysics, University of Chicago, Illinois
• OSTI ID: 6451398
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 94:A3; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALFVEN WAVES
BEAMS
COMPUTERIZED SIMULATION
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ENERGY TRANSFER
FLUIDS
HYDROMAGNETIC WAVES
ION BEAMS
ION DENSITY
MAGNETIC FIELDS
MATHEMATICAL SPACE
PHASE SPACE
SHOCK WAVES
SIMULATION
SOLAR ACTIVITY
SOLAR WIND
SPACE
TRAPPING