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CCFE-PR(15)702015
This paper presents a numerical investigation of isolated filament dynamics in a simulation geometry representative of the scrape-off layer (SOL) of the Mega Amp Spherical Tokamak (MAST) previously studied in [N.R.Walkden et.al, Plasma Phys. Control. Fusion, 55 (2013) 105005]. This paper focuses on the evolution of filament cross-sections at the ou…
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CCFE-PR(15)512015
Drift-reduced plasma fluid models are commonly used in plasma physics for analytic studies and simulations, so the validity of such models must be verified for the regions of parameter space in which tokamak plasmas exist. By deriving and comparing the linear dispersion relations for the drift-wave instability for both a drift-reduced model and a f…
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CCFE-PR(15)182015
Non-local closures allow kinetic effects on parallel transport to be included in fluid simulations. This is especially important in the scrape-off layer, but to be useful there the non-local model requires consistent kinetic boundary conditions at the sheath. A non-local closure scheme based on solution of a kinetic equation using a diagonalized mo…
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CCFE-PR(15)172015
Measurements of intensity fluctuation of light emission within the divertor volume of MAST provide strong evidence for the existence of filamentary structures within the private flux region (PFR). These filaments are observed in L-mode and H-mode confinement regimes. Correlation analysis of the camera data supports the hypothesis that the filaments…
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CCFE-PR(15)792015
The propagation of filaments in the Scrape Off Layer (SOL) of tokamaks largely determines the plasma profiles in the region. In a conduction limited SOL, parallel temperature gradients are expected, such that the resistance to parallel currents is greater at the target than further upstream. Since the perpendicular motion of an isolated filament is…
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CCFE-PR(15)1252015
The ball pen probe (BPP) technique is used successfully to make profile measurements of plasma potential, electron temperature, and radial electric field on the Mega Amp Spherical Tokamak. The potential profile measured by the BPP is shown to significantly differ from the floating potential both in polarity and profile shape. By combining the BPP p…
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2014
This paper presents simulations of isolated 3D filaments in a slab geometry obtained using a newly developed 3D reduced fluid code, written using the BOUT þþ framework. First, systematic scans were performed to investigate how the dynamics of a filament are affected by its amplitude, perpendicular size, and parallel extent. The perpendicular size…
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2010
The impact of Resonant Magnetic Perturbations (RMPs) on the edge of MAST L-mode plasmas is studied using a mid-plane reciprocating probe equipped with a Gundestrup probe head. A strong impact on the characteristics of the ion saturation current fluctuations is observed just inside the separatrix, with a broadening of the power spectrum and an asymm…
Showing 31 - 38 of 38 UKAEA Paper Results