Simulations of a gradual solar energetic particle event observed by Helios 1, Helios 2, and IMP 8
ASTROPHYSICAL JOURNAL(2015)
摘要
In this work, a gradual solar energetic particle (SEP) event observed by multi-spacecraft has been simulated. The time profiles of SEP fluxes accelerated by an interplanetary shock in the three-dimensional interplanetary space are obtained by solving numerically the Fokker-Planck focused transport equation. The interplanetary shock is modeled as a moving source of energetic particles. By fitting the 1979 March 01 SEP fluxes observed by Helios 1, Helios 2, and IMP 8 with our simulations, we obtain the best parameters for the shock acceleration efficiency model. And we also find that the particle perpendicular diffusion coefficient with the level of similar to 1%-3% of parallel diffusion coefficient at 1 AU should be included. The reservoir phenomenon is reproduced in the simulations, and the longitudinal gradient of SEP fluxes in the decay phase, which is observed by three spacecraft at different locations, is more sensitive to the shock acceleration efficiency parameters than that is to the perpendicular diffusion coefficient.
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关键词
Sun: activity,Sun: coronal mass ejections (CMEs),Sun: particle emission
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