R. Felton
DEMO aims to (i) integrate, demonstrate and validate all relevant technology necessary to convert fusion energy to electrical energy and (ii) that the machine and its operations are economically and environmentally acceptable. To maintain the efficiency and availability of the machine, there are several physics and combined physics/technology issue…
PublishedD.R. Mason X. Yi M.A. Kirk S.L. Dudarev
Using in situ transmission electron microscopy (TEM), we have observed nanometre scale dislocation loops formed when an ultra-high-purity tungsten foil is irradiated with a very low fluence of self-ions. Analysis of the TEM images has revealed the largest loops to be predominantly of prismatic 1/2{111} type and of vacancy character. The formation o…
PublishedL.W.G. Morgan L.W. Packer
The generation of tritium in sufficient quantities is an absolute requirement for a next step fusion device such as DEMO due to the scarcity of tritium sources. A number of methods have been proposed in order to meet this requirement, however a lithium-based tritium breeding blanket that surrounds the fusion plasma is widely considered to be the mo…
PublishedA.J. Thornton A. Kirk The Mast Team
The power load to the divertor surfaces is a key concern for future devices such as ITER, due to the thermal limits on the material surface. One factor that characterises the heat flux to the divertor is the fall off length in the SOL, which recent empirical scalings have shown could be as small as 1 mm. These predictions are based on a multi-machi…
PublishedS. C. Chapman R. O. Dendy T. N. Todd N. W. Watkins A. J. Webster F. Calderon J. Morris JET EFDA Contributors
A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in …
PublishedC. J. Ham I. T. Chapman A. Kirk S. Saarelma
It is known that magnetic perturbations can mitigate edge localized modes (ELMs) in experiments, for example, MAST [Kirk et al., Nucl. Fusion 53, 043007 (2013)]. One hypothesis is that the magnetic perturbations cause a three dimensional corrugation of the plasma and this corrugated plasma has different stability properties to peeling-ballooning mo…
PublishedMarthe Bacal Roy Mcadams Elizabeth Surrey
This paper discusses the possibility that there is an enhancement of volume production due to gettering of atomic hydrogen by the caesium deposited on the walls, which reduces the negative ion destruction by associative and non-associative detachment. Such an enhancement would take place for all plasma grid bias voltages. Furthermore at plasma grid…
PublishedA. Czarnecka V. Bobkov I. H. Coffey L. Colas P. Jacquet K. D. Lawson E. Lerche C. Maggi M.-L. Mayoral T. Pütterich D. Van Eester JET-EFDA Contributors
Magnetically confined plasmas, such as those produced in the tokamak JET, contain measurable amounts of impurity ions produced during plasma-wall interactions (PWI) from the plasma-facing components and recessed wall areas. The impurities, including high- and mid-Z elements such as tungsten (W) from first wall tiles and nickel (Ni) from Inconel str…
PublishedVladimir F. Shevchenko Simon J. Freethy Billy K. Huang Roddy G. L. Vann
A Synthetic Aperture Microwave Imaging (SAMI) system has been designed and built to obtain 2-D images at several frequencies from fusion plasmas. SAMI uses a phased array of linearly polarised antennas. The array configuration has been optimised to achieve maximum synthetic aperture beam efficiency. The signals received by antennas are down-convert…
PublishedL. Garzotti J. Figueiredo C. M. Roach M. Valovic D. Dickinson G. Naylor M. Romanelli R. Scannell G. Szepesi The Mast Team
Reactor grade plasmas are likely to be fuelled by pellet injection. This technique transiently perturbs the profiles, driving the density profile hollow and flattening the edge temperature profile. After the pellet perturbation, the density and temperature profiles relax towards their quasi-steady-state shape. Microinstabilities influence plasma co…
Published