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 = < δ V r δ V p >, where V r and V p 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 V p (t), V r (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 < δ V r δ V p > 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)