Solar Flare Particle Propagation: Comparison of a New Analytic Solution with Spacecraft Measurements
- Creators
- Lupton, J. E.
-
Stone, E. C.
Abstract
A new radial solution has been obtained to the Fokker-Planck equation for solar flare particle propagation that includes the effects of convection, energy change, and anisotropic diffusion with κ_γ = constant. It is assumed that the particles are injected impulsively at a single point and that there is a free escape boundary. In addition, the azimuthal solution derived by Burlaga, which was based on κ_θ ∝ γ², has been modified to include some of the effects of solar rotation. With an outer boundary at ~2.7 AU, a solar wind velocity of ̃400 km/sec, and κ_γ ≈ 2 to 8 × 10^(20) cm²/sec, the complete solution gives reasonable fits to the time profiles of 1- to 10-Mev protons from 'classical' flare-associated events observed with the Caltech solar and galactic cosmic ray experiment aboard Ogo 6. It is not necessary to invoke a scatter free region near the sun in order to reproduce the fast rise times observed for west limb events, indicating that κ_γ = constant is a better description of conditions inside 1 AU than is κ_γ ∝ γ. The radial solution also provides insight into the possible dependence of the observed decay times on various parameters and can be used as the basis for an illustrative calculation of the evolution of the vector anisotropy.
Additional Information
Copyright © 1973 by the American Geophysical Union. (Received March 14, 1972; accepted October 30, 1972.) We are grateful to R. E. Vogt who has been intimately involved with the Ogo 6 experiment. We also appreciate useful discussions with J. R. Jokipii and S. S. Murray. This work was supported in part by the National Aeronautics and Space Administration under contract NAS5-9312 and Grants NGR-05-002-160 and NGL-05-002-007. One of us (Lupton) has received valuable support from a NDEA fellowship and a NASA traineeship, and the other (Stone) was an Alfred P. Sloan research fellow during this work. The Editor wishes to thank R. C. Englade and L. J. Gleeson for their assistance in evaluating this paper.Attached Files
Published - 1972-04.pdf
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Additional details
- Eprint ID
- 44737
- Resolver ID
- CaltechAUTHORS:20140408-092921534
- NASA
- NAS5-9312
- NASA
- NGR 05-002-160
- NASA
- NGL 05-002-007
- NDEA fellowship
- Alfred P. Sloan Foundation
- Created
-
2014-04-08Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Space Radiation Laboratory
- Other Numbering System Name
- Space Radiation Laboratory
- Other Numbering System Identifier
- 1972-04