Turbulent structure in the edge plasma of the TEXT tokamak

Abstract

A reversal has been observed in the mean phase velocity of the turbulent fluctuations in the edge plasma of the TEXT tokamak. The observations can be described by a model in which the wave velocity in the lab frame is dominated by a nonuniform Er×B velocity and a gradient driven drift. The measurements also exhibit a localized instability which occurs in the region of maximum velocity shear.

Pedestal and edge electrostatic turbulence characteristics from an XGC1 gyrokinetic simulation

“…The conditional spectrum S(k θ |f ) has been utilized in numerous experiments [25,14,26] to identify unique features in fluctuating plasma quantities, such as the dominant turbulence mode (e.g. ITG, TEM, etc.).…”

The role of turbulence–flow interactions in L- to H-mode transition dynamics: recent progress

“…A physics-based model of the L-H transition threshold power is therefore needed to confidently extrapolate to auxiliary heating requirements for ITER and future burning plasma experiments. It was recognized early on that the H-mode edge barrier forms as fluctuations are suppressed due to E × B flow shear [9][10][11] in a narrow (few cm wide) radial layer just inside the last closed flux surface (LCFS) [12][13][14][15]. While the paradigm of flow-shear suppression has been experimentally verified in the H-mode edge transport barrier as well as in internal transport barriers [16][17][18], the sequence of events leading to the formation of a highly sheared E × B jet flow layer has been the subject of intensive research.…”

Reduction of chaotic particle transport driven by drift waves in sheared flows

“…3 Experiments indicate that at the plasma edge the observed anomalous particle transport is mainly caused by the particle E ϫ B drift. [5][6][7] Several experiments show that particle transport can be reduced by changing the electric field radial profile at the plasma edge. 8,9 One experimental procedure to achieve this reduction is the biasing scheme.…”