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The impact of generalized sheath boundary conditions, taking into account the sheath perturbations driven by the Alfvén waves, on the propagation of plasma filaments at the tokamak edge is considered. A model describing the filament dynamics and containing new boundary conditions is developed. Estimates of the model control parameter—the sheath impedance—on the plasma transport are obtained. Simulations of the filament dynamics under the conditions characteristic of edge plasmas in NSTX and Alcator C‑Mod tokamaks are performed. It is shown that the sheath impedance leads to an increase in the mean values of the electrostatic potential and advection velocities of filaments, in agreement with experimental observations, requiring, at the same time, a more detailed description of the Alfvén wave reflection from the conducting surfaces of the installations. [ABSTRACT FROM AUTHOR]

The cumulative impact of the inhomogeneous distribution of the plasma temperature and electromagnetic effects on dynamics of plasma filaments in the hot edge plasma of a tokamak, characterized by small values of the parameter , is analyzed. The physical model describing the filament dynamics is presented. Estimates of the scrape-off-layer plasma parameters, for which electromagnetic and temperature effects can have a substantial impact on the filament dynamics in conditions of the low ratio of the plasma pressure to the pressure of the magnetic field, are obtained. The model equations are used for three-dimensional simulations of the macroscopic motion of filaments in plasma, the parameters of which are similar to the parameters of the peripheral plasma of the tokamak T-15MD, for different types of the spatial distribution of the electron temperature inside the filaments. It is shown that simultaneously taking electromagnetic and temperature effects into account can lead to a considerable departure of the filament trajectories of motion from those in the electrostatic case. [ABSTRACT FROM AUTHOR]

Recent experimental observations of divertor plasma turbulence at the ASDEX Upgrade tokamak have demonstrated the onset of strong fluctuations of plasma radiation intensity in the near X-point region within the inner divertor leg, when the machine was operating with the pronounced asymmetry in detachment of plasma between the inner and outer divertors. As been recently shown, one of the possible mechanisms responsible for these fluctuations can be related to the current-convective instability (CCI). In this contribution, we assess whether the CCI can drive turbulence with spatial and temporal parameters similar to those observed lately in DIII-D experiments. It is demonstrated that the CCI drives saturated plasma fluctuations, dominated by low-frequency modes with toroidal wavelengths on the order of the machine circumference in the inner divertor region—features that are similar to turbulence characteristics found in experiments. [ABSTRACT FROM AUTHOR]

Abstract: A pellet injector was installed on the HL-2A tokamak, and preliminary experiments were performed recently. In this paper, the impact of pellet injection on the scrape-off-layer intermittent transport is described. High-field-side pellet injection experiments are also reported. [ABSTRACT FROM AUTHOR]

In this paper we establish the asymptotic limit of the three dimensional Vlasov-Poisson equation with strong external magnetic field. The guiding center approximation is investigated in the three dimensional case with a non-constant magnetic field. In the long time asymptotic limit, the motion can be split in two parts: one stationary flow along the lines of the magnetic field and the guiding center motion in the orthogonal plane of the magnetic field where classical drift velocities and invariants (magnetic moment) are recovered. [ABSTRACT FROM AUTHOR]