NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Mean free paths of energetic particles at very large heliodistances (Pioneer 11 at 20 AU)The parallel mean free path and the diffusion coefficient parallel to the magnetic field line are derived from magnetic field data at 20 AU to characterize heliospheric modulation and energetic-particle/magnetic-field interaction. The computational method of Moussas et al. (1975, 1982) is employed, and the values of the parallel mean free path are shown to be significantly larger than the values estimated in studies of up to 6 AU. The distance dependence of the parallel diffusion mean free path is found to follow a power law, and the diffusion coefficient dependence upon energy is determined by a constant mean free path and the velocity of the particle. The contribution of the diffusion coefficient perpendicular to the magnetic field is expected to dominate the radial diffusion coefficient of cosmic rays, although the contribution of the diffusion parallel to the field is important with respect to the small-scale structure of intensity gradients.
Document ID
19920066845
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Moussas, X.
(Athens, National University Greece; Imperial College of Science, Technology, and Medicine, London, United Kingdom)
Quenby, J. J.
(Imperial College of Science, Technology, and Medicine London, United Kingdom)
Theodossiou-Ekaterinidi, Z.
(Siemens A.E.; Athens, National University Greece)
Valdes-Galicia, J. F.
(Universidad Nacional Autonoma de Mexico Coyoacan, Mexico)
Drillia, A. G.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Roulias, D.
(Athens, National University Greece)
Smith, E. J.
(JPL Pasadena, CA, United States)
Date Acquired
August 15, 2013
Publication Date
July 1, 1992
Publication Information
Publication: Solar Physics
Volume: 140
Issue: 1, Ju
ISSN: 0038-0938
Subject Category
Space Radiation
Accession Number
92A49469
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available