Intermittent transport events in a cylindrical plasma device: experiment and simulation

Abstract

Abstract. The origin of intermittent fluctuations in the plasma edge of a linearly magnetized plasma column is investigated and closely compared to threedimensional global numerical simulations. The intermittent character is caused by radially propagating turbulent structures. The radial propagation of the structures is due to the self-consistent potential perturbation associated with them. Their formation is closely linked to transport events caused by nonlinear drift-wave fluctuations. In the formation region a sheared azimuthal flow velocity is observed, which is driven by the Reynolds stress.

Intermittent Behavior of Local Electron Temperature in a Linear ECR Plasma

“…Because the convection of blobs significantly enhances cross-field transport and may leads to deterioration in edge plasma confinement, the statistical properties of fluctuations in the edge are crucially important. Intermittent transport of similar turbulent structures has also been studied by linear devices [2,3].…”

Turbulent transport across shear layers in magnetically confined plasmas

“…How these poloidal velocities are related to the radial transport is studied here. It has been reported that drift waves inside the shear layer are correlated with blobs outside of it [9,23,24]. Drift waves preferentially propagate in the poloidal direction and not in the radial one across the shear layer as interchange modes do.…”

Formation of turbulent structures and the link to fluctuation driven sheared flows

“…The spatiotemporal evolution of the fluctuations across the plasma cross-section has been analyzed in detail in Ref. [16]. Similar to the experimental situation the dynamics in the maximum density gradient region is dominated by drift waves with low modenumbers (m = 1, 2).…”

“…In both cases clear evidence has been found that the turbulent Reynolds stress drives a fluctuating m = 0 potential perturbationφ m=0 . The radial profile of the Reynolds stress peaks in a region, in which turbulent structures peel-off from quasi-coherent drift modes [16]. Although the time-averaged amplitude ofφ m=0 is much smaller compared to the contribution of the fluctuations with larger modenumbers (smaller scales), it can become dominant if the energetic transfer R rate gets sufficiently large.…”