Model of ionic charge states of impulsive solar energetic particles in solar flares

Abstract

We have fully developed a computational model (ESCAPE) to follow the behavior of the mean charge state of ions in solar energetic particle events while the ions are accelerated. Our model combines acceleration with energy loss and charge stripping low in the corona. Therefore we have taken into account explicitly the second‐order Fermi‐type stochastic acceleration under a magnetohydrodynamic turbulence. We have found that the mean ionic charge states depend sensitively on plasma parameters as source temperature or density and on acceleration parameters as efficiency or the timescales for acceleration. Our model finds a systematic increase of the ionic charge states with energy for all the ions studied. This energy dependence differs between ions, and in the energy range of observations this dependence is stronger for heavy ions.