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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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CCFE-PR(17)522017
The accumulation of impurities in the core of magnetically confined plasmas, resulting from standard collisional transport mechanisms, is a known threat to their performance as fusion energy sources. Whilst the axisymmetric tokamak systems have been shown to benefit from the effect of temperature screening, that is an outward flux of impurities dri…
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CCFE-PR(17)062017
Using an ab initio approach, we explore the stability of small vacancy and vacancychromium clusters in dilute body-centred cubic Fe-Cr alloys. To explain experimental observations described in C.D. Hardie et al., J. Nucl. Mater. 439, 33 (2013) and showing the occurrence of Cr segregation in low-Cr alloys, we investigate if chromium can form stable …
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CCFE-PR(17)112017
This work presents the first evidence of helical flow in RFX-mod q(a) < 2 tokamak plasmas. The flow pattern is characterized by the presence of convective cells with m = 1 and n = 1 periodicity in the poloidal and toroidal direction, respectively. A similar helical flow deformation has been observed in the same device when operatedfas a Reversed…
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CCFE-PR(17)122017
This paper presents for the first time a statistical validation of predictive TRANSP simulations of plasma temperature using two transport models, GLF23 and TGLF, over a database of 80 baseline H-mode discharges in JET-ILW. While the accuracy of the predicted Te with TRANSP-GLF23 is affected by plasma collisionality, the dependency of predictions o…
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CCFE-PR(17)532017
Fusion demonstration (DEMO) concepts are facing challenges in safety and licensing in part due to uncertainties with in-vessel components validation, which relate directly to the materials and design criteria used for assessments. These challenges come from the designed operation under unprecedented environmental conditions and reliance on the perf…
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CCFE-PR(17)612017
The vacancies produced in high energy collision cascades can form in irradiated tungsten vacancy clusters or vacancy prismatic dislocation loops. Moreover, vacancy loop can easily transform to a planar vacancy cluster. We investigated the formation energies of these three types of vacancy defects as a function of number of vacancies using three EAM…
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CCFE-PR(17)462017
Tokamak plasma current start-up assisted by Electron Bernstein waves (EBW) has been demonstrated successfully in a number of experiments. The dynamic start-up phase involves a change in field topology, as the initially open magnetic field lines form closed flux surfaces (CFS) under the initiation of a plasma current. This change in field topology w…
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CCFE-PR(17)592017
A data analysis method for the spherical indenter geometry has been produced that capitalises on recent hardware developments of instrumented indenters, specifically the high data capture rate. The data analysis is based on a multi-cycle load test regime and the main refinement is the fitting of the data along the unload curve to a Hertzian contact…
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CCFE-PR(17)482017
The ITER tokamak needs to sustain a plasma in a regime of high energy confinement (H-mode) to exceed fusion breakeven where power output exceeds input. H-mode plasmas are typically unstable to edge localised modes (ELMs), in which plasma escapes and strikes the plasma facing components. Scaled up to ITER, the energy released by ELMs can cause criti…
Showing 1421 - 1430 of 2590 UKAEA Paper Results