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Published 1971 | Accepted Version
Book Section - Chapter Open

Transport of Solar Flare Protons-Comparison of a New Analytic Model with Spacecraft Measurements


An analytic solution has now been obtained to the complete Fokker-Planck equation including the effects of convection, interplanetary deceleration and acceleration, corotation, and anisotropic diffusion with κ∣∣ constant and with κ⊥∝r^2. With the boundary of the diffusing region at 2.3 AU, a solar wind velocity of 400 km sec^(-1), κ∣∣ ~7x10^(20) cm^2 sec^(-1), and impulsive injection on the line of force connecting to the earth, the solution yields a time to maximum for the particle flux of ~10 h and an exponential decay time of ~25 h. Several solar flare particle events have been observed with the Caltech Solar and Galactic Cosmic Ray Experiment on 0G0-6. Detailed comparisons of the calculated time dependence of the fluxes with these observations of 1-70 MeV protons show that the model adequately describes both the rise and decay times, indicating that κ∣∣ = constant is a better representation of conditions inside 1 AU than is κ∣∣ ∝r.

Additional Information

We are grateful to R. E. Vogt who has been intimately involved with the OG0-6 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 No. NAS5-9312 and Grant Nos. NGR-05-002-160 and NGL 05-002-007. One of us (J.E.L.) has received valuable support from an NDEA Fellowship and a NASA Traineeship.

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August 19, 2023
August 19, 2023