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Solar Flare Particle Propagation: Comparison of a New Analytic Solution with Spacecraft Measurements

Lupton, J. E. and Stone, E. C. (1973) Solar Flare Particle Propagation: Comparison of a New Analytic Solution with Spacecraft Measurements. Journal of Geophysical Research A, 78 (7). pp. 1007-1018. ISSN 0148-0227. doi:10.1029/JA078i007p01007.

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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.

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Stone, E. C.0000-0002-2010-5462
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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.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
NASANGR 05-002-160
NASANGL 05-002-007
Alfred P. Sloan FoundationUNSPECIFIED
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory1972-04
Issue or Number:7
Record Number:CaltechAUTHORS:20140408-092921534
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44737
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Deposited On:08 Apr 2014 21:16
Last Modified:10 Nov 2021 16:55

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