Turbulence Velocimetry of Tangential Fast Imaging Data on QUEST

Abstract

A particle image velocimetry technique based on orthogonal dynamic programming is developed to measure the time resolved flow field of the fluctuating structures at the plasma edge and scrape off layer. This nonintrusive technique can provide two dimensional velocity fields at high spatial and temporal resolution from a fast framing image sequence and hence can provide better insights in plasma flow as compared to conventional probe measurements. Applicability of the technique is tested with simulated image pairs. Finally, it is applied to tangential fast visible images of QUEST as a test case to estimate the scrape off layer flow in Ohmic and ECRH driven plasma discharges.

Scrape Off Layer Flow Characteristics in the Spherical Tokamak QUEST

“…We try track the plasma eddies born from the cross field transport by the particle image velocimetry (PIV) technique [14]. PIV relies on optical alignments of various types of patterns as a global transformation between consecutive image strips and thereby it is most likely to track the eddy propagation velocity (u ||ed ).…”