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2011
The knowledge of the mean free path (mfp) of the negative ions is important for many purposes, e.g. evaluating the distance from which the ions can be extracted, or understanding the significance of experimental results. We will present the mfp for similar conditions in volume and caesium seeded sources. It appears that the mfp is longer in the cae…
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2011
Following earlier publication of a model of crack flow and filtering based on a 2-D crack representation, the model has been improved and submitted to validation by comparison with data from a number of other theoretical and experimental studies. This process has led to improved understanding of gas flow and filtering in real crack geometry and pro…
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2011
The activation cross sections of ( d,p ), ( d, 2 n ), ( d, 3 n ), and ( d, 2 p ) reactions on 63 , 65 Cu were measured in the energy range from 4 to 20 MeV using the stacked-foil technique. Then, following the available elastic-scattering data analysis that provided the optical potential for reaction cross-section calculations, an increased effort …
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2011
During plasma instabilities, “surface currents” can flow at the interface between the plasma and the surrounding vacuum, and in most cases, they are a harmless symptom of the instability that is causing them. Large instabilities can lead to “disruptions,” an abrupt termination of the plasma with the potential to damage the machine in which …
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2011
It is often observed that large sawteeth trigger the neoclassical tearing mode (NTM) well below the usual threshold for this instability. At the same time, fast particles in the plasma core stabilize sawteeth and provide these large crashes. The paper presents results of first experiments in ASDEX Upgrade for destabilization of fast particle stabil…
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2011
The L-mode interchange turbulence in the edge and Scrape Off Layer of the tight aspect ratio tokamak MAST is investigated numerically. The dynamics of the boundary plasma is studied using the 2D drift-fluid code ESEL, which has previously shown good agreement with large aspect ratio machines. In this context, a MAST-TCV comparison is presented in o…
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2011
The edge of a Tokamak plasma is interesting due to its geometrical structure that is difficult to model either analytically or computationally, its tendency to form "transport barriers" with increased confinement of energy and momentum, and the edge-localised instabilities associated with transport barriers that threaten the lifetime of components …
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2011
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2011
The Joint European Torus (JET) operates using deuterium as a fuel but has also operated in D-T mode where the fusion reaction is fuelled by deuterium and tritium. To justify the safety of D-D and D-T experiments, safety reports are produced to obtain approval for the experimental campaigns. The Safety Case has recently undergone a periodic safety r…
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2011
Verification of nonlinear microstability codes is a necessary step before comparisons or predictions of turbulent transport in toroidal devices can be justified. By verification we mean demonstrating that a code correctly solves the mathematical model upon which it is based. Some degree of verification can be accomplished indirectly from analytical…
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