Implications of the GSFC Q sub 3 model for trapped particle motion

Journal Article · Wed Jun 01 00:00:00 EDT 1988 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA093iA06p05505· OSTI ID:5257215

Acuna, M H; Connerney, J E.P. ^[1]; Ness, N F ^[2]

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1. NASA Goddard Space Flight Center, Greenbelt, MD (USA)
2. Univ. of Delaware, Newark (USA)

The adiabatic motion of energetic charged particles in the Uranian magnetosphere is studied by numerical computation of field geometric invariants associated with the GSFC Q{sub 3} magnetic field model. Comparison of the compound L shell values along the Voyager 2 trajectory with those associated with the Uranian satellites Ariel, Umbriel, and Miranda as a function of their orbital position allows the prediction of times and locations where absorption effects of charged particles should be observable. Systematic differences in the observed and predicted counting rate (flux) minima suggest that the age of an absorption event must be taken into account and that a better understanding of the particles' drift history is needed to explain the observed features. As a consequence of the large tilt of the dipole term with respect to the rotation axis, the Uranian moons sweep a large amount of L shells during their orbital motion and occupy several different L minima defined in the text. Comparisons with previous results obtained from the offset tilted dipole model of Ness et al. (1986) yield a complex picture regarding the predicted and observed times for absorption signatures, depending on the minimum L value used for comparison. In spite of this complexity, a general pattern is evident in which the predicted locations for the absorption signatures fall inside (i.e., at smaller radial distances) the observed features, thus suggesting that radial diffusion effects as well as the drift history of the trapped particles must be taken into account to explain the energetic charged particle observations. It is thus expected that observed absorption signatures which are young with respect to the location of the absorbing body and the Voyager 2 spacecraft better reflect the geometry of the magnetic field.

• OSTI ID: 5257215
• Journal Information: Journal of Geophysical Research; (United States), Vol. 93:A6; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
PLANETARY MAGNETOSPHERES
TRAPPING
URANUS PLANET
ABSORPTION
ADIABATIC PROCESSES
CHARGED PARTICLES
COMPARATIVE EVALUATIONS
MAGNETIC FIELDS
MATHEMATICAL MODELS
MOTION
SATELLITES
VOYAGER SPACE PROBES
ATMOSPHERES
EVALUATION
PLANETARY ATMOSPHERES
PLANETS
SPACE VEHICLES
VEHICLES
640107* - Astrophysics & Cosmology- Planetary Phenomena