Generation and dynamics of SOL corrugated profiles

P Ghendrih,E Serre,G Ciraolo,Y Asahi,V Grandgirard,R Tatali,P Donnel,G Dif-Pradalier,Y Sarazin,S Baschetti,H Bufferand,T Cartier-Michaud,X Garbet,E Caschera,P Tamain,C Gillot,G Latu

doi:10.1088/1742-6596/1125/1/012011

Abstract

The staircase transport regime reported in kinetic simulations of plasma turbulent transport in magnetic confinement is recovered with a simple 2D fluid model allowing for reduced damping of the zonal flows. Some of the complex dynamics of the kinetic zonation regime are recovered but the pattern of the corrugation appears to be sinusoidal with a characteristic scale comparable to that of turbulence modes with largest spectral energy, in contrast to regimes observed in global and flux-driven kinetic simulations. Enhanced zonal flows govern both an overall reduction of the SOL width and a gradual steepening of the gradients with distance to the separatrix.

Highlights

A major step towards a better understanding of confinement performance has been achieved when more relevant handling of the zonal flow physics [1] has been implemented in turbulent transport simulations [2]
Model for Scrape-Off Layer turbulence To address the physics of corrugation generation in profiles, and their significance with respect to transport, we address the simplest possible turbulent system, named for simplicity after the code as the TOKAM2D system
With relatively small changes of the initial SOL turbulence model we have recovered a regime with corrugated profiles [16, 17, 21]

Summary

Introduction

A major step towards a better understanding of confinement performance has been achieved when more relevant handling of the zonal flow physics [1] has been implemented in turbulent transport simulations [2]. For increasing values of the growth rate, one finds that the density gradient length required to trigger the instability decreases close to exponentially, Left Hand Scale, blue plain line for kx = 0, axy = 0, and dashed black line for kx = ky, axy = 1. Note that this dependence on ky2/k2 governs the factor 2 difference between the required density gradient length of these two cases.

Flux-surface-averaged fields

Findings

Discussion and Conclusion