Non-Gaussian transport in strong plasma turbulence

Abstract

The transport of test particle ensembles moving in turbulent electrostatic fields governed by the Hasegawa–Mima equation is investigated. It ranges from subdiffusive to ballistic, depending on the size (in terms of thermal ion Larmor radii) of the domain considered, and on the magnitude of the background density gradient. In addition to the electrostatic potential, other fields, notably the vorticity and the Weiss field, prove to be very useful in accounting for particle dynamics and transport. For example, the existence of well defined core-circulation cell vortex structure in the Weiss field gives the most reliable guide to particle trapping, while locales of zero vorticity define regions of filamentary particle flow. Differential transport of guiding center particles and energetic particles gyrating with significant Larmor radius is investigated; the latter is strongly inhibited.