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Title: Energetic particle drift motions in the outer dayside magnetosphere

Models of the geomagnetic field predict that within a distance of approximately one earth radius inside the dayside magnetopause, magnetic fields produced by the Chapman-Ferraro magnetopause currents create high-latitude minimum-B ''pockets'' in the geomagnetic field. Drift-shell branching caused by the minimum-B pockets is analyzed and interpreted in terms of an adiabatic shell branching and rejoining process. We examine the shell-branching process for a static field in detail, using the Choe-Beard 1974 magnetospheric magnetic field model. We find that shell branching annd rejoining conserves the particle mirror field B/sub M/, the fieldline integral invariant I, and the directional electron flux j. We determine the spatial extent of the stable trapping regions for the Choe-Beard model. We develop an adiabatic branching map methodology which completely identifies and describes the location of shell-branching points and the adiabatic trajectories of particles on branched shells, for any model field. We employ the map to develop synthetic pitch angle distributions near the dayside magnetopause by adiabatically transforming observed midnight distributions to the dayside. We find that outer dayside lines contain particles moving on branched and unbranched shells, giving rise to distinctive pitch angle distribution features. We find a good correlation between the pitch angles which markmore » the transition from branched to unbranched shells in the model, and the distinctive features of the OGO-5 distributions. In the morning sector, we observe large flux changes at critical pitch angles which correspond to B-pocket edges in the model. Measurements on inbound passes in the afternoon sector show first the adiabatic particle shadow, then the arrival of fluxes on rejoined shells, then fluxes on unbranced shells - in accord with model predictions. 204 refs., 138 figs., 2 tabs.« less
Authors:
Publication Date:
OSTI Identifier:
5597620
Report Number(s):
UCRL-53806
ON: DE88005097
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Technical Report
Resource Relation:
Other Information: Thesis (Ph.D.). Portions of this document are illegible in microfiche products. Original copy available until stock is exhausted
Research Org:
Lawrence Livermore National Lab., CA (USA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; EARTH MAGNETOSPHERE; ELECTRON DRIFT; ELECTRON SPECTROMETERS; EXPERIMENTAL DATA; MATHEMATICAL MODELS; DATA; EARTH ATMOSPHERE; INFORMATION; MEASURING INSTRUMENTS; NUMERICAL DATA; SPECTROMETERS 640201* -- Atmospheric Physics-- Auroral, Ionospheric, & Magetospheric Phenomena