UKAEA Journals

Showing 1 - 10 of 11 Journals Results
2019
UKAEA-CCFE-PR(19)75

The evolution of the JET high performance hybrid scenario, including central accumulation of the tungsten (W) impurity, is reproduced with predictive multi-channel integrated modelling over multiple confinement times using first-principle based models. 8 transport channels are modelled predictively, with self-consistent sources, radiation and magne…

Preprint Purchase
2018
UKAEA-CCFE-PR(18)54

Neoclassical and turbulent heavy impurity transport in tokamak core plasmas are determined by main ion temperature, density and toroidal rotation profiles. Thus, in order to reproduce experimental behaviour of W accumulation, integrated modelling of main ion heat and particle transport is a vital prerequisite. For the first time, the quasilinear …

Preprint Published
2017
CCFE-PR(17)42

Quantitative comparisons are presented between gyrokinetic simulations and experimental values of the carbon impurity peaking factor in a database of JET H-modes during the carbon wall era. These plasmas feature strong NBI heating, hence high values of toroidal rotation and correponding gradient. Furthermore, the carbon profiles present particularl…

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)54

The recently proposed set of zeroth-order moment equations to model poloidal density asymmetries induced by temperature anisotropies in rotating tokamak plasmas (R. Bilato et al., Nuclear Fusion 54 (2014) 072003) is here extended to account for the effects of the localization of the ion cyclotron (IC) resonance on the poloidal inhomogeneity of the …

Preprint Published
2015
CCFE-PR(15)44

The effects of poloidal asymmetries and heated minority species are shown to be necessary to accurately describe heavy impurity transport in present experiments in JET and ASDEX Upgrade. Plasma rotation, or any small background electrostatic field in the plasma, such as that generated by anisotropic external heating can generate strong poloidal den…

Preprint Published
2015
CCFE-PR(15)02

Non-linear local electromagnetic gyrokinetic turbulence simulations of the ITER standard scenario H-mode are presented for the q = 3 / 2 and q = 2 surfaces. The turbulent transport is examined in regions of velocity space characteristic of electrons heated by electron cyclotron waves. Electro- magnetic fluctuations and sub-dominant micro-tearing mo…

Preprint Published
2011

New transport experiments on JET indicate that ion stiffness mitigation in the core of a rotating plasma, as described by Mantica et al. [ Phys. Rev. Lett. 102, 175002 (2009) ] results from the combined effect of high rotational shear and low magnetic shear. The observations have important implications for the understanding of improved ion core con…

Published
2009

This workshop on transport in fusion plasmas is the thirteenth in a series. Previously they have been held under the auspices of the EU and US Transport Task Forces (TTFs), with J Connor as the EU TTF chair. However, the EU Transport Task Force has now been subsumed into the EFDA (European Fusion Development Agreement) Topical Group for Transport (…

Published
2008

Impurity transport is an important topic for ITER as impurity density in tlie core has to stay below a relative concentration of 5 x 10~^ [1] to reach ignition conditions. The reasons for that is mainly impurity radiation leading to cooling. In the edge region on the other hand site, higher impurity densities, going along with radiation energy loss…

Published