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UKAEA-CCFE-PR(19)172019
We describe the development of a new object kinetic Monte Carlo code where the elementary defect objects are off-lattice atomistic configurations. Atomic-level transitions are used to transform and translate objects, to split objects and to merge them together. This gradually constructs a database of atomic configurations- a set of relevant defect …
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UKAEA-CCFE-PR(19)072018
Ray-tracing techniques are applied to divertor filtered imaging, a diagnostic that has long been plagued by polluting reflected light features in metal walled fusion machines. A physically realistic surface reflection model is developed from a Cook-Torrence microfacet BRDF model. Camera calibration images of in-vessel point lights at JET are use…
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UKAEA-CCFE-PR(18)392018
Tungsten has long been the favoured armour material for plasma facing high heat flux components proposed for future fusion reactors, but studies examining the use of tungsten or other refractory metals in the underlying cooled structures have historically excluded them, leaving current concepts heavily dependent on copper alloys such as copper chro…
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UKAEA-CCFE-PR(18)152018
Particle transport is of a great importance for understanding physics of tokamak plasmas and planning future experiments on larger machines such as ITER. The subject was intensively studied in the past, particularly in relation to density peaking and presence of anomalous inward particle convection in L- and H-mode. While in the L-mode case presenc…
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CCFE-PR(17)672017
The tritium required for ITER will be supplied from the CANDU production in Ontario, but while Ontario may be able to supply 8 kg for a DEMO fusion reactor in the mid-2050s, it will not be able to provide 10 kg at any realistic starting time. The tritium required to start DEMO is uncertain within a wide margin; stocks would likely have to be shared…
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CCFE-PR(17)582017
Methods for density control are of critical importance for future long pulse tokamaks. The EMC3-EIRENE code is being used to investigate the applicability of 3D non-axisymmetric fields for density control in standard and advanced divertor configurations in spherical tokamaks. Part of this effort is understanding Scrape Off layer (SOL) transport mec…
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CCFE-PR(17)432017
A potential threat to the performance of magnetically confined fusion plasmas is the problem of impurity accumulation, which causes the concentration of highly charged impurity ions to rise uncontrollably in the center of the plasma and spoil the energy confinement by excessive radiation. It has long been thought that the collisional transport of i…
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2017
The heating neutral beam injectors (HNBs) of ITER are designed to deliver 16.7MWof 1 MeVD0 or 0.87 MeVH0 to the ITER plasma for up to 3600 s. They will be the most powerful neutral beam (NB) injectors ever, delivering higher energy NBs to the plasma in a tokamak for longer than any previous systems have done. The design of the HNBs is based on the …
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CCFE-PR(16)332016
The microstructure and thermal stability of V-4Cr-4Ti-1.8Y-0.4Ti3SiC2 alloy, fabricated by 60 hr mechanical milling of blended powders followed by spark plasma sintering (SPS) and hot isostatic pressing, has been investigated. Analysis was undertaken using orientation image maps obtained from the electron backscattering and transmission Kikuchi dif…
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CCFE-PR(16)452016
It is shown that ITG turbulence close to the threshold exhibits a long time behaviour, with smaller heat fluxes at later times. This reduction is connected with the slow growth of long wave length zonal flows and, consequently, the numerical dissipation on these flows must be sufficient small. Close to the nonlinear threshold for turbulence generat…
Showing 51 - 60 of 107 UKAEA Paper Results