We investigate suprathermal ion dynamics in simple magnetized toroidal
plasmas in the pres- ence of electrostatic turbulence driven by the ideal
interchange instability. Turbulent fields from fluid simulations are used in
the non-relativistic equation of ion motion to compute suprathermal tracer ion
trajectories. Suprathermal ion dispersion starts with a brief ballistic phase,
during which particles do not interact with the plasma, followed by a
turbulence interaction phase. In this one simple system, we observe the entire
spectrum of suprathermal ion dynamics, from subdiffusion to superdiffusion,
depending on beam energy and turbulence amplitude. We estimate the duration of
the ballistic phase and identify basic mechanisms during the interaction phase
that determine the character of suprathermal ion dispersion upon the beam
energy and turbulence fluctuation amplitude.Comment: 5 pages, 3 figures, accepted in PR
