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UKAEA-CCFE-PR(24)2242024
To evaluate hydrogen diffusion within diamond, a series of molecular dynamics simulations have been carried out in which diffusion coefficients and activation energies were determined. Diamond grown via chemical vapour deposition (CVD) contains a high hydrogen concentration within grain boundaries, because of this, common tilt grain boundaries (111…
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UKAEA-CCFE-CP(23)602022
Diamond’s intrinsic hardness, excellent thermal conductivity and low atomic number make it a highly promising candidate as a plasma facing material. However, as with the previously used graphite, concerns over tritium retention and resultant chemical etching have so far limited research interest in the use of synthetic diamond. In order to study …
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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(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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2014
First simultaneous measurements of deuterium-deuterium (DD) and deuterium-tritium neutrons from deuterium plasmas using a Single crystal Diamond Detector are presented in this paper. The measurements were performed at JET with a dedicated electronic chain that combined high count rate capabilities and high energy resolution. The deposited energy sp…
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2014
It is shown that rapid substantial changes in heating rate can induce transitions to improved energy confinement regimes in zero-dimensional models for tokamak plasma phenomenology. We examine for the first time the effect of step changes in heating rate in the models of Kim and Diamond [Phys. Rev. Lett. 90, 185006 (2003)] and Malkov and Diamond [P…
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2014
In 2011-2012, an experimental campaign with a significant yield of fusion neutrons was carried out on the JET tokamak. During this campaign the facility was equipped with two diamond detectors based on natural and artificial CVD diamond. These detectors were designed and manufactured in State Research Center of Russian Federation TRINITI. The detec…
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2013
Application of lower hybrid (LH) current drive in tokamak plasmas can induce both co- and countercurrent directed changes in toroidal rotation, depending on the core q profile. For discharges with q0 < 1, rotation increments in the countercurrent direction are observed. If the LH-driven current is sufficient to suppress sawteeth and increase q0 abo…
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2013
Energy transport and confinement in tokamak fusion plasmas is usually determined by the coupled nonlinear interactions of small-scale drift turbulence and larger scale coherent nonlinear structures, such as zonal flows, together with free energy sources such as temperature gradients. Zero-dimensional models, designed to embody plausible physical na…
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