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2008
A comparison is presented of measured and simulated parallel flows in the low field side scrape-off layer of MAST Ohmic shots. Simulations with B2SOLPS5.0 code reproduce the experimentally observed co-current rotation direction. The absolute values of the simulated Mach number are smaller than those of the measured ones; the difference might reach …
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2008
A full orbit test-particle approach is used to study the collisional transport of impurity (carbon) ions in spherical tokamak (ST) plasmas with transonic and subsonic toroidal flows. The efficacy of this approach is demonstrated by reproducing the results of classical transport theory in the large aspect ratio limit. The equilibrium parameters used…
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2008
In a fusion device such as a tokamak, it is well known that an unstable external kink mode, driven either by the plasma current or pressure, produces an external magnetic field perturbation, which induces stabilizing image currents in the surrounding conducting structures, such as the vacuum vessels made of low resistivity materials. The image curr…
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2008
Utilizing a capability to vary neutral beam torque injection in the DIII-D [J. L. Luxon, Nucl. Fusion 42 , 614 (2002)] tokamak, m / n =2/1 neoclassical tearing mode onset thresholds are found to fall by about one unit in βN , from 3 to 2, in ITER-like sawtoothing high-energy confinement modes of plasma operation [R. Aymar, Plasma Phys. Control. Fu…
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2008
Core localized Alfvén eigenmodes in DIII-D [J. L. Luxon, Nucl. Fusion 42 , 614 (2002)] and Joint European Torus JET [P. H. Rebut and B. E. Keen, Fusion Technol. 11 , 13 (1987)] plasmas are driven by deuterium neutral beam ions traveling well below the Alfvén speed. Modes are observed in reverse magnetic shear discharges with deuterium ion velocit…
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2008
A simple formula for predicting the width of a saturated island, formed as a consequence of tearing perturbation of linear force-free fields in cylindrical geometry, is derived. The formula makes it possible to calculate the saturated island width in terms of the values of parameters characterizing the initial force-free equilibrium and can be appl…
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2008
A perturbative three-dimensional analysis is presented of Alfvén waves in a magnetic X-point configuration with a strong longitudinal guide field. The waves are assumed to propagate in the direction of the X-line, and both the plasma beta and equilibrium plasma current are taken to be zero. This provides a simple model of Alfvén wave propagation …
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2008
The tokamak plasma boundary, which is typically identified with the area of open field lines known as the scrape-off layer (SOL), determines the degree of plasmawall interaction. SOL physics, much of which is concerned with the exhaust (removal) of particles and energy from the plasma, has been one of the major topics investigated on JET during the…
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2008
Edge Localised Modes (ELMs) are periodic disturbances of the plasma periphery occurring in tokamaks with an H-mode edge transport barrier. As a result, a fraction of the plasma energy present in the confined hot edge plasma is transferred to the open field lines in the divertor region, ultimately appearing at the divertor target plates. These event…
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2008
In this paper we model (111) self-interstitial defects, or crowdions, using an extended version of the analytical Frenkel-Kontorova model. We use a more general potential than the traditional sinusoidal one, and find that it can better describe the lattice potentials experienced by crowdions in the body-centred-cubic transition metals, as calculate…
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