UKAEA Journals

Showing 1 - 10 of 394 Journals Results
2021
UKAEA-CCFE-PR(21)08

A survey of the correlation between temperature and density gradient lengths ( and ) has been performed for the near SOL regions in the ASDEX Upgrade tokamak. In common with previous studies, the near SOL temperature and density gradient length ratio, , is found to be close to unity across a wide range of plasmas. However, it is found that it is po…

Preprint Published
2021
UKAEA-CCFE-PR(21)02

In quiescent H-mode (QH-mode) regime, edge harmonic oscillations (EHOs) are believed to provide necessary radial transport to prevent occurrence of large edge localized modes. A systematic modeling study is performed here on the low-n EHOs in a DIII-D QH-mode plasma [Chen et al. 2016 Nucl. Fusion 56 076011], by utilizing the MARS-Q code [Liu et a…

Preprint
2020
UKAEA-CCFE-PR(20)141

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…

Preprint Published
2020
UKAEA-CCFE-PR(20)138

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, w…

Preprint
2020
UKAEA-CCFE-PR(20)132

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…

Preprint
2020
UKAEA-CCFE-PR(20)130

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…

Preprint Purchase
2020
UKAEA-CCFE-PR(20)103

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…

Preprint
2020
UKAEA-CCFE-PR(20)76

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…

Preprint Published
2020
UKAEA-CCFE-PR(20)70

Determining tensile properties from small punch test is being pursued actively in the nuclear industry due to the limited volume of material such tests use compared with standard tests which can be critical when considering active or development samples. One of the crucial challenges in harnessing the full potential of this technique is formulat…

Preprint Published
2020
UKAEA-CCFE-PR(20)21

Local linear gyrokinetic simulations show that electron temperature gradient (ETG) instabilities are the fastest growing modes for kyρi >~ 0.1 in the steep gradient region for a JET pedestal discharge (92174) where the electron temperature gradient is steeper than the ion temperature gradient. Here, ky is the wa…

Preprint Purchase
The published version of this paper is currently under embargo and will be available on 29/10/2021