UKAEA Journals

Showing 1 - 10 of 26 Journals Results
2021
UKAEA-CCFE-PR(21)27

Tungsten is one the primary candidate materials for the high neutron flux, high temperature components of a future demonstrate fusion reactor. Despite this, there is a lack of data on W under fusion relevant neutron doses and irradiation temperatures. Transmutation reactions result in the production of Re and Os solute atoms, at a rate which is …

Preprint
2021
UKAEA-CCFE-PR(21)13

Tridiagonal matrix inversion is an important operation with many applications. It arises frequently in solving discretized one-dimensional elliptic partial differential equations, and forms the basis for many algorithms for block tridiagonal matrix inversion for discretized PDEs in higher-dimensions. In such systems, this operation is often the sca…

Preprint
2020
UKAEA-CCFE-PR(20)79

Point defects in body-centred cubic Fe, Cr and concentrated random magnetic Fe-Cr are investigated using density functional theory and theory of elasticity. The volume of a substitutional Cr atom in ferromagnetic bcc Fe is approximately 18% larger than the volume of a host Fe atom, whereas the volume of a substitutional Fe atom in antiferromagnetic…

Preprint Published
2020
UKAEA-CCFE-PR(20)74

The impacts of ions and neutrons in metals causes cascades of atomic collisions that expand and shrink, leaving microstructure defect debris, i.e. interstitial or vacancy clusters or loops of different sizes. In [A. De Backer, A. E. Sand, K. Nordlund, L. Lun´eville, D. Simeone, and S. L. Dudarev. EPL, 115(2):26001, 2016.], we described a method…

Preprint Published
2018
UKAEA-CCFE-PR(20)129

Typically applied to non-linear simulations of MHD instabilities relevant to magnetically confined fusion, the JOREK code was originally developed with a 2D grid composed of isoparametric bi-cubic Bezier finite elements, that are aligned to the magnetic equilibrium of tokamak plasmas. To improve the applicability of these simulations, the grid-gene…

Preprint Purchase
2019
UKAEA-CCFE-PR(19)69

The equipment used in some welding techniques (e.g. tungsten inert gas alternating current welding or capacitor discharge stud welding) can induce high electromagnetic fields inside the operator due to the large time-varying electric currents involved in the process. The European Union (EU) Directive 2013/35/EU provides guidelines and recommendatio…

Preprint
2017
CCFE-PR(17)64

In a fusion tokamak, the plasma of hydrogen isotopes is in contact with tungsten at the surface of a divertor. In the bulk of the material, the hydrogen concentration profile tends towards dynamic equilibrium between the flux of incident ions and their trapping and release from defects, either native or produced by ion and neutron irradiation. The …

Preprint Published
2017
CCFE-PR(17)47

Heavy impurities, such as tungsten (W), can exhibit strongly poloidally asymmetric density profiles in rotating or radio frequency heated plasmas. In the metallic environment of JET, the poloidal asymmetry of tungsten enhances its neoclassical transport up to an order of magnitude, so that neoclassical convection is expected to dominate over turbul…

Preprint
2016
CCFE-PR(16)45

It is shown that ITG turbulence close to the threshold exhibits a long time behaviour, with smaller heat fluxes at later times. This reduction is connected with the slow growth of long wave length zonal flows and, consequently, the numerical dissipation on these flows must be sufficient small. Close to the nonlinear threshold for turbulence generat…

Preprint Published
2016
CCFE-PR(16)21

The damage produced by primary knock-on atoms (PKA) in W has been investigated from the threshold displacement energy (TDE) where it produces one Self Interstitial Atom (SIA) – vacancy pair to larger energies, up to 100 keV, where a large molten volume is formed. The TDE has been determined in different crystal directions using the Born Oppenheim…

Preprint Published