UKAEA Journals

Showing 491 - 500 of 1684 Journals Results
2018
UKAEA-CCFE-PR(18)5

As shown experimentally, the interplay between screw and edge dislocations in uranium dioxide (UO2) determines the low-temperature plasticity in this material. For the latter, neither the mobility of screw dislocations nor the mechanisms of their glide had been assessed — up until now. It is particularly interesting to evaluate the mobility of 1/…

Preprint Published
2018
UKAEA-CCFE-PR(18)14

Measurements are reported of electromagnetic emission close to the cyclotron frequency of energetic ions in JET plasmas heated by waves in the ion cylotron range of frequencies (ICRF). Hydrogen was the majority ion species in all of these plasmas. The measurements were obtained using a sub-harmonic arc detection (SHAD) system in the transmission li…

Preprint Published
2018
UKAEA-RACE-PR(18)01

The first advanced robot many of us will experience may well be an autonomous vehicle (or driverless car). Autonomous Vehicle (AV) technology has made huge strides in recent years moving from a mainstay of science fiction to the first forays on public roads. The promise in AV stems from a wide range of potential and perceived benefits, the bigges…

Preprint
2018
UKAEA-CCFE-PR(18)39

Tungsten has long been the favoured armour material for plasma facing high heat flux components proposed for future fusion reactors, but studies examining the use of tungsten or other refractory metals in the underlying cooled structures have historically excluded them, leaving current concepts heavily dependent on copper alloys such as copper chro…

Preprint Published
2018
UKAEA-CCFE-PR(18)46

Some of the main plasma physics challenges associated with achieving the conditions for commercial fusion power in tokamaks are reviewed. The confinement quality is considered to be a key factor, having an impact on the size of the reactor and exhaust power that has to be managed. Plasma eruptions can cause excessive erosion if not mitigated, with …

Preprint Published
2018
UKAEA-CCFE-PR(18)38

Conventional linear elasticity theory predicts the strain fields of a dislocation core to diverge, whereas it is known from atomistic simulations that strains at dislocation cores remain finite. We present an analytical solution to a generalised, variational Peierls-Nabarro model of edge dislocation displacement fields that features a finite core w…

Preprint Published
2018
UKAEA-CCFE-PR(18)10

In Ion-Temperature-Gradient (ITG) driven turbulence, the resonance condition leads to ion particle turbulent transport coefficients significantly larger than electron particle turbulent transport coefficients. This is shown in non-linear gyrokinetic simulations and explained by an analytical quasilinear model. It is then illustrated by JETTO-QuaLi…

Preprint Published
2018
UKAEA-CCFE-PR(18)50

There are many sources of random and systematic error in composition quantification by atom probe, however, often only statistical error is reported. Identification of ions and overlaps or interferences of peaks in the mass spectrum are one major source of uncertainty much larger than counting error. These overlaps can be solved using maximum likel…

Preprint Published
2018
UKAEA-CCFE-PR(18)45

In magnetic fusion devices, unwanted non-axisymmetric magnetic eld perturbations, known as error fields (EF), can have detrimental effects on plasma stability and confinement. To minimize their impact on plasma performances and on the available operational space, it is important to identify the EF sources and develop EF control strategies. MAST Up…

Preprint Purchase
The published version of this paper is currently under embargo and will be available on 11/08/2022
2018
UKAEA-CCFE-PR(18)7

The line tension model of obstacle hardening is modified to account for the thermally activated, kink-limited glide of 1=2h111i screw dislocations, allowing application to the plastic flow of bcc metals. Using atomistically-informed dislocation mobility laws, Frenkel-Kontorova simulations and a simplified dislocation obstacle model, we identify a …

Preprint Published