Energetic particle acceleration in a 3D magnetic field reconnection   model: a role of MHD turbulence
  The role of MHD turbulence in the cosmic ray acceleration process in a volume with a reconnecting magnetic field is studied by means of Monte Carlo simulations. We performed modelling of proton acceleration with the 3D analytic model of stationary reconnection of Craig et al. (1995) providing the unperturbed background conditions. Perturbations of particle trajectories due to a turbulent magnetic field component were simulated using small-amplitude pitch-angle momentum scattering, enabling modelling of both small and large amplitude turbulence in a wide wave vector range. Within the approach, no second-order Fermi acceleration process is allowed. Comparison of the acceleration process in models involving particle trajectory perturbations to the unperturbed one reveals that the turbulence can substantially increase the acceleration efficiency, enabling much higher final particle energies and flat particle spectra. 
Tomasz Kobak, Michal Ostrowski (Astronomical Observatory of   Jagiellonian University)