Journals

Showing 1 - 10 of 18 Journals Results
2020
UKAEA-CCFE-PR(20)22

A linear perturbation theory is used to model the MHD stability of tokamak equilibria under the application of external 3D magnetic perturbations [C.C. Hegna, Physics of Plasmas 21 :072502, 2014]. The symmetry breaking produces the coupling of toroidal n modes. We use ELITE [H.R. Wilson et al., Physics of Plasmas 9 :1277, 2002] to produce …

Preprint Published
2020
UKAEA-CCFE-PR(19)03

A new 1D divertor plasma code, SD1D, has been used to examine the role of recombination, radiation, and momentum exchange in detachment. Neither momentum or power losses by themselves are found to be sufficient to produce target ion flux rollover in detachment; radiative power losses are required to a) limit and reduce the ionization source and …

Preprint Published
2019
UKAEA-CCFE-PR(19)73

The here presented work studies the dynamics of filaments using 3D full-f fluid simulations in the presence of detached background profiles. It was found that evolving the neutrals on the time-scale of the filament did not have a significant impact on the dynamics of the filament. In general a decreasing filament velocity with increasing plasma den…

Preprint
2019
UKAEA-CCFE-PR(19)55

In ITER and DEMO, achieving detachment at lower densities would allow to reduce the amount of impurity seeded and to improve confinement by running at lower separatrix densities. Analytic models predict that a increase of total flux expansion would allow such a reduction in upstream density at detachment. However, both experiments and modelling …

Preprint Purchase
2019
UKAEA-CCFE-PR(19)16

The STORM module of BOUT++ [L. Easy et al., Phys. Plasmas 21, 122515 (2014)] is generalized to simulate plasma turbulence at the periphery of tokamak devices in diverted configuration and it is used to carry out three-dimensional nonlinear flux-driven simulations in double null configuration with realistic experimental par…

Preprint Published
2018
UKAEA-CCFE-PR(18)21

This paper presents the effect of self-consistent plasma backgrounds including plasma-neutral interactions, on the dynamics of filament propagation. The principle focus is on the influence of the neutrals on the filament through both direct interactions and through their influence on the plasma background. Both direct and indirect interactions infl…

Preprint Published
2017
CCFE-PR(17)70

It has been previously demonstrated in (Li et al 2016 Nuclear Fusion 56 126007) that the optimum upper/lower coil phase shift ΔΦopt for alignment of RMP coils for ELM mitigation depends sensitively on q95, and other equilibrium plasma parameters. Therefore, ΔΦopt is expected to vary widely during the current ramp …

Preprint Published
2017
CCFE-PR(17)01

Tokamak plasmas are confined by a magnetic field that limits the particle and heat transport perpendicular to the field. Parallel to the field the ionised particles can move freely, so to obtain confinement the field lines are “closed" (ie. form closed surfaces of constant poloidal flux) in the core of a tokamak. Towards, the edge, however, the …

Preprint Published
2017
CCFE-PR(17)50

The interaction of L-mode and inter-ELM Scrape-Off Layer (SOL) filaments is investigated by simulating the dynamics of two seeded density perturbations with different initial separation. A numerical campaign of 2D and 3D simulations is presented to explore the effect that different filaments' perpendicular size and relative distance have on their r…

Preprint Published
2016
CCFE-PR(16)27

Retarding field energy analysers (RFEAs) have been used to compare the ion temperature ( T i ) of large plasma filaments with the background plasma (composed of small scale filaments) at the midplane and divertor target in L mode discharges in the Mega Amp Spherical Tokamak (MAST). At low densities, at the midplane and divertor, at distances from 2…

Preprint Published