Non-diffusive Transport in a Simple Flux-driven Plasma Turbulence System

A simple 2D flux-driven drift-wave type plasma fluid turbulence model has been developed to demonstrate the affect on the overall transport due to the interplay between turbulent driven gradient relaxation and self-generated flows. The mixed overall transport characteristics in this system can then be captured through the non-diffusive transport framework. Super-diffusive transport has been observed as a consequence of the turbulent relaxation process triggered by the combination of a flux-driven background profile and a critical gradient. Sub-diffusive transport can arise from self-generated sheared poloidal flows due to the inhomogeneity in the geometry of the sources. The diffusive character exists in regimes where neither the super-diffusive nor the sub-diffusive element is dominant. With an externally applied sheared poloidal flow, once again the sub-diffusive character dominates. Finally, a relation between Lagrangian trajectories and a passive scalar advection will be shown, which provides a potential bridge between experimental transport measurements and analytical theory.