Search for Zonal Flows and Momentum Transport due to Edge Turbulence - - PowerPoint PPT Presentation

Search for Zonal Flows and Momentum Transport due to Edge Turbulence

S.J. Zweben, J.L. Terry, J.R Myra, D.A. D’Ippolito, D.A. Russell et al

• zonal flows are fluctuating m ~ 0 poloidal flows which can

in theory regulate turbulence, and which have been seen in NSTX, DIII-D, AUG, T-10 etc (e.g. Fujisawa PPCF ‘09)

• turbulence-induced momentum transport can be evaluated

from Reynolds stress R = <δVr δVp>, where Vr and Vp are turbulence velocities, as has been done in JET, TJ-II etc.

search ¡for ¡these ¡using ¡fast ¡GPI ¡camera ¡data ¡ and ¡compare ¡results ¡with ¡turbulence ¡codes ¡ ¡

Preliminary Results

• Calculate Vp(t), Vr(t) from GPI images at 400,000 frames/sec
• No obvious coherent zonal flows seen so far (f ~1 - 20 kHz)
• But clear non-zero <δVr δVp> seen in this frequency range

Plan for Analysis / Experiment

• Analyze existing GPI camera data at 400,000 frames/sec

to find cases with clearest zonal flows / Reynolds stress in SOL (~1000 shots from 2009/2010 with ~0.4 TB data)

• Attempt comparison with SOLT model for selected cases

(this is a nonlinear 2D electrostatic edge turbulence code by the Lodestar group, which has zonal flows and blobs)

• Repeat and extend dataset of clearest results with new MP
• optimize for best GPI data in SOL with D gas puff
• repeat with He gas puff to try to improve contrast
• take simultaneous ‘X-region’ GPI, probe data and other

edge turbulence data to look at structure of ZF / RS ( ~ 0.5 – 1 run day)