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Author Ashour-Abdalla, M. ♦ Richard, R. L. ♦ Zelenyi, L. M.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword PHYSICS ♦ MAGNETOTAIL ♦ PLASMA DENSITY ♦ PLASMA DRIFT ♦ DISTRIBUTION FUNCTIONS ♦ GLOBAL ASPECTS ♦ PLASMA FILAMENT
Abstract Moments of plasma distributions observed in the magnetotail vary with different time scales. In this paper the authors attempt to explain the observed variability on intermediate timescales of {approximately}10-20 min that result from the simultaneous energization and spatial structuring of solar wind plasma in the distant magnetotail. These processes stimulate the formation of a system of spatially disjointed, highly accelerated filaments (beamlets) in the tail. They use the results from large-scale kinetic modeling of magnetotail formation from a plasma mantle source to calculate moments of ion distribution functions throughout the tail. Statistical restrictions related to the limited number of particles in their modeled system naturally reduce the spatial resolution of their results, but they show that their model is valid on intermediate spatial scales {Delta}x {times} {Delta}z {approximately} 1 R{sub E} x 1000 km. The complexity of the pattern is related to the spatial interference between beamlets accelerated at various locations within the distant tail which mirror in the strong near-Earth magnetic field. The results obtained enable the authors to view the magnetotail plasma as consisting of two different populations: a tailward-Earthward system of highly accelerated beamlets interfering with each other, and an energized quasithermal population which gradually builds as the Earth is approached. In the near-Earth tail, these populations merge into a hot quasi-isotropic ion population typical of the near-Earth plasma sheet. The transformation of plasma sheet boundary layer (PSBL) beam energy into central plasma sheet (CPS) quasi-thermal energy occurs in the absence of collisions or noise. This paper also clarifies the relationship between the global scale where an MHD description might be appropriate and the lower intermediate scales where MHD fails and large-scale kinetic theory should be used. 49 refs., 15 figs.
ISSN 01480227
Educational Use Research
Learning Resource Type Article
Publisher Date 1995-10-01
Publisher Place United States
Journal Journal of Geophysical Research
Volume Number 100
Issue Number A10


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