Trajectory trapping and the evolution of drift turbulence beyond the quasilinear stage

TL;DR

This paper investigates how ion trapping influences the evolution of drift turbulence in magnetized plasmas, revealing mechanisms for large-scale structure formation and mode damping beyond quasilinear approximations.

Contribution

It introduces ion trapping as a key physical process shaping the nonlinear evolution of drift turbulence and explains the formation of large-scale potential structures and flow dynamics.

Findings

Ion trapping leads to large-scale potential structures via inverse cascade.

Trapping and potential motion reduce drift mode growth rates.

Ion flows in opposite directions dampen drift turbulence and influence zonal flows.

Abstract

Test modes on turbulent magnetized plasmas are studied taking into account the ion trapping that characterizes the E x B drift in the background turbulence. We show that trappyng provides the physical mechanism for the formation of large scale potential structures (inverse cascade) observed in drift turbulence. Trapping combined with the motion of the potential with the diamagnetic velocity determines ion flows in opposite directions, which reduce the growth rate and eventually damps the drift modes. It also determine transitory zonal flow modes in connection with compressibility effect due to the polarization drift in the background turbulence.