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UKAEA-CCFE-PR(20)1412020
Using ab initio density function theory calculations, we have determined the structure of self-interstitial atom (SIA) defects in the most commonly occurring face-centred cubic (FCC) metals. The most stable SIA defects in Al, Ca, Ni, Cu, Pd and Ag are the {100} dumbbells whereas octahedral SIA configurations have the lowest energy in Pt, R…
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UKAEA-CCFE-PR(20)1382020
The electron runaway phenomenon in plasmas depends sensitively on the momentum space dynamics. However, efficient simulation of the global evolution of systems involving runaway electrons typically requires a reduced fluid description. This is needed for example in the design of essential runaway mitigation methods for tokamaks. In this paper, we p…
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UKAEA-CCFE-CP(20)1222020
A thorough physics and engineering analysis of alternative divertor configurations is carried out by examining benefits and problems by comparing the baseline single null solution with a Snowflake, an X- and a Super-X divertor. It is observed that alternative configurations can provide margin and resilience against large power fluctuations, but the…
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UKAEA-CCFE-PR(20)1322020
Mechanical constitutive models of metals undergoing deformation in three dimensions can be challenging to validate without loss of generality. For example, creep-induced stress relaxation in stainless steels has previously been studied using axisymmetric notched-bar tests which control the triaxiality of the initial stress state. However, such expe…
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UKAEA-CCFE-PR(20)1302020
In this paper we investigate the residual deformation field in the vicinity of nano-scratch experiments generated using two tip geometries in a (100) Cu single crystal. We compare the deformation with that from indentation, in an attempt to understand the mechanisms of deformation in tangential sliding. The lattice rotation fields are mapped exp…
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UKAEA-CCFE-CP(20)1112020
The Mega Amp Spherical Tokamak (MAST) is currently being extensively upgraded to provide a system that will be able to add to the knowledge base for ITER as well as testing innovative reactor systems such as the Super-X divertor. MAST-U will have increased coil system and power supply capability. Therefore, to ensure operation of MAST-U within safe…
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UKAEA-CCFE-CP(20)1062020
The measurement of the fusion neutron yield provides a direct relationship with fusion power and is hence an important measure of experimental performance. In pulsed neutron emission scenarios, such as those experienced in dense plasma focus devices, inertial confinement fusion and even in short-pulse tokamak experiments, considerations of the dyna…
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UKAEA-CCFE-PR(20)1032020
We develop a dynamic model for the evolution of an ensemble of hundreds of interacting irradiation-induced mobile nanoscale defects in a micrometre size sample. The model uses a Langevin defect dynamics approach coupled to a finite element model, treated using the superposition method. The elastic field of each defect is described by its elastic…
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UKAEA-CCFE-CP(20)902020
Investment in past fusion experiments has been motivated largely by the study of tokamak physics, and has been vital to provide a sound physics basis for design of a power reactor. However, meeting the challenge of realising fusion energy production will require considerable and increasing investment in facilities for testing and development of fus…
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UKAEA-CCFE-PR(20)762020
In tokamak operation the control of dangerous MHD instabilities, possibly in r-t scenarios, must rely on prompt robust diagnostics of the state and stability of the system. The set of magnetic signals measured on the outside of the plasma boundary, based on the Zakharov-Shafranov, Shkarowsky, Wootton (ZSSW) current moments has been always used f…
Showing 81 - 90 of 500 UKAEA Paper Results