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UKAEA-CCFE-PR(20)912020
Ion implantation is widely used as a surrogate for neutron irradiation in the investigation of radiation damage on the properties of materials. Due to the small depth of damage, micromechanical methods must be used to extract material properties. In this work, nanoindentation has been applied to ion irradiated silicon carbide to extract radiatio…
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UKAEA-CCFE-PR(20)922020
Raman spectroscopy has been used to identify defective bonding in neon and silicon ion irradiated single crystals of 6H-SiC. Observable differences exist in the CC bonding region corresponding to different defect structures for neon and silicon ion implantations. Evidence of oxidation during high temperature ion implantation is observed as C-O a…
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UKAEA-CCFE-PR(20)1092020
Tungsten is the prime candidate material for the plasma facing divertor system and first wall armor of future nuclear fusion reactors. However, the understanding of the microstructural and chemical evolution of pure tungsten under neutron irradiation is relatively unknown, in part due to a lack of experimental data on this topic. Here, single cr…
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UKAEA-CCFE-PR(20)1082020
We performed ab initio density functional theory simulations of 1/2{111} interstitial dislocation loops, closed and open vacancy loops, {100} interstitial loops and voids in tungsten, using simulation cells involving from 2000 to 2700 atoms. The size of the loops transcends the microscopic scale and reaches the mesoscopic scale where as…
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UKAEA-CCFE-PR(20)1052020
Dislocation climb is an important high temperature process of metals plasticity, responsible for phenomena such as creep, swelling, or hardening. Climb is defined by the ability of dislocations to leave their original glide plane by interaction with point defects. As such, dislocation climb is controlled by point defect diffusion/absorption/emis…
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UKAEA-CCFE-PR(20)1042020
Thermal diffusivity measurements of samples transmitting thermal radiation require adjustments to the data treatment procedures in laser flash analysis. Conventionally, an unconstrained diathermic model is used. Current results show that the alternative coupled radiative-conductive models produce substantially different results — for instance,…
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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-PR(20)1022020
Modification of the external tearing index, Δ’ext , by magnetic feedback is analytically investigated, for the purpose of controlling the resistive plasma resistive wall mode (RP-RWM). The matching method is pursued, by deriving expressions for the close-loop Δ’ext and by linking it to the counterpart from the inner layer. Various…
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UKAEA-CCFE-CP(20)1032020
One of the issues faced by future fusion devices will be high target heat loads. Alternative divertors are a potential solution to the heat loads. They have been investigated in TCV and DIII-D, and will be investigated on MAST-U. To evaluate their effectiveness, accurate target heat flux and power balance measurements are required in these machines…
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UKAEA-CCFE-PR(20)1012020
A method to quantify the energy transfer among turbulent structures using singular value decomposition (SVD) is presented. We apply the method to numerical turbulence data obtained from a global plasma simulation using the Hasegawa-Wakatani fluid model, in which the Kelvin-Helmholtz instability plays a dominant role. Using the SVD method,…
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