Bidirectional electron anisotropies in the distant tail: ISEE-3 observations of polar rain
A detailed observational treatment of bidirectional electrons (50 approx.500 eV) in the distant magnetotail (r greater than or equal to 100 R/sub E/) is presented. It is found that electrons in this energy range commonly exhibit strong, field-aligned anisotropies in the tail lobes. Because of large tail motions, the ISEE-3 data provide extensive sampling of both the north and south lobes in rapid succession, demonstrating directly the strong asymmetries that exist between the north and south lobes at any one time. The bidirectional fluxes are found to occur predominantly in the lobe directly connected to the sunward IMF in the open magnetosphere model (north lobe for away sectors and south lobe for toward sectors). Electron anisotropy and magnetic field data are presented which show the transition from unidirectional (sheath) electron populations to bidirectional (lobe) populations. Taken together, the present evidence suggests that the bidirectional electrons that we observe in the distant tail are closely related to the polar rain electrons observed previously at lower altitudes. Furthermore, these data provide strong evidence that the distant tail is comprised largely of open magnetic field lines in contradistinction to some recently advanced models.
- Research Organization:
- Los Alamos National Lab., NM (USA); Jet Propulsion Lab., Pasadena, CA (USA)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 6281232
- Report Number(s):
- LA-UR-85-4310; CONF-8510254-1; ON: DE86004737
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANISOTROPY
ASYMMETRY
CHARGED-PARTICLE PRECIPITATION
DATA
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRON PRECIPITATION
ELECTRONS
ELEMENTARY PARTICLES
ENERGY RANGE
EV RANGE
EV RANGE 10-100
EV RANGE 100-1000
EXPERIMENTAL DATA
FERMIONS
INFORMATION
LEPTONS
MAGNETOTAIL
MAPPING
NUMERICAL DATA