Investigation of different small-scale flux-rope acceleration scenarios for energetic particles in the solar wind near Earth

Our previous kinetic transport theoretical development for energetic particle acceleration by and large-scale transport through solar wind regions with numerous dynamic small-scale flux ropes in the strong guide/background field limit is further analyzed and extended. The basic flux-rope acceleration mechanisms and the issue of compressibility are further clarified by applying concepts such as magnetic curvature and shear flow to these structures. A set of new coupled focused-transport-MHD turbulence equations is presented for modeling coherent and stochastic energetic particle acceleration by small-scale flux ropes self-consistently. Furthermore, test particle coherent and stochastic acceleration rates are compared for the different flux-rope acceleration mechanisms, and stochastic acceleration and pitch-angle scattering rates for flux ropes and Alfven waves are compared, for energetic protons at Earth.