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UKAEA-CCFE-PR(18)372018
Ultrafast irradiation can drive the electrons in a material out of thermal equilibrium with the nuclei, producing hot, transient electronic states that modify the interatomic potential energy surface. We present, for the first time, a rigorous formulation of two-temperature molecular dynamics that can accommodate these electronic effects in the fo…
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UKAEA-CCFE-PR(18)212018
This paper presents the effect of self-consistent plasma backgrounds including plasma-neutral interactions, on the dynamics of filament propagation. The principle focus is on the influence of the neutrals on the filament through both direct interactions and through their influence on the plasma background. Both direct and indirect interactions infl…
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UKAEA-CCFE-PR(18)222018
The operation of a tokamak designed to test the sustainability of a thermonuclear grade plasma like the International Tokamak Experimental Reactor (ITER) presents several challenges. Among them is the necessity of fuelling the plasma to reach the density required to generate enough fusion power to achieve Q = 10 and, at the same time, to protect th…
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UKAEA-CCFE-PR(18)232018
Ray-tracing techniques are applied to bolometry, a diagnostic particularly sensitive to machine geometry due to the effect of volume sampling. Sightlines from the ASDEX-Upgrade bolometer foils were ray-traced with a path tracing algorithm, where the optical path is represented by a statistical bundle of ray paths connecting the foil surface with th…
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UKAEA-CCFE-PR(18)242018
Computational models created for neutronics assessment through solid geometry conversion are often specific to the analysis being performed. The use of unstructured mesh geometry has the potential to reduce the build time of MCNP models, reduce inaccuracies introduced through flux averaging over different components and material mixing, and make us…
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UKAEA-CCFE-PR(18)272018
This paper explores the application of the parareal algorithm to simulations of ELMs in ITER plasma. The primary focus of this research is identifying the parameters that lead to optimum performance. Since the plasma dynamics vary extremely fast during an ELM cycle, a straightforward application of the algorithm is not possible and a modification t…
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UKAEA-CCFE-PR(18)282018
Fishbones are ubiquitous in high-performance JET plasmas and are typically considered to be unimportant for scenario design. However, during recent high-performance hybrid experiments, sporadic and explosive fishbones have been observed which correlate with a reduction in performance and main chamber hotspots. Clear evidence has been obtained of fu…
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UKAEA-CCFE-PR(18)292018
FISPACT-II is an advanced activation/transmutation and inventory code that employs the most up-to-date and sophisticated nuclear data forms, including the full TENDL-2017 library. TENDL includes residual nuclide production for incident particle energies up to 200 MeV. To address the needs of activation-transmutation simulation in incident-particle …
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UKAEA-CCFE-PR(18)302018
We present a new analysis of nanoscale lattice defects observed after low-dose in situ self-ion irradiation of tungsten foils at cryogenic temperature. For decades, defect counts and size-frequency histograms have been the standard form of presenting a quantitative analysis of the nanoscale “black-dot” damage typical of such irradiations. Here …
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UKAEA-CCFE-PR(18)22018
Precipitation-hardened Cu-Cr-Zr will be used in heat-sink components in the Iter tokomak. After irradiation it will not be possible to test the mechanical properties of Cu-Cr-Zr using conventional, large-scale, techniques and methods requiring reduced sample sizes will have to be used. Spherical nano-indentation is one such method. In this work, Cu…
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