UKAEA Journals

Showing 1 - 10 of 35 Journals Results
2021
UKAEA-CCFE-PR(21)58

This paper presents recent progress on the studies of neoclassical tearing modes (NTMs) on TCV, concerning the new physics learned and how this physics contributes to a better real-time (RT) control of NTMs. A simple technique that adds a small (sinusoidal) sweeping to the target electron cyclotron (EC) beam deposition location has proven effective…

Preprint
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)07

A study of a dataset of JET plasma with the Be/W ITER-like wall (JET-ILW) shows that reaching the edge MHD ballooning limit leads to confinement degradation. However, unlike JET plasma with a carbon wall (JET-C), the JET-ILW plasma stays in a marginal dithering phase for a relatively long period, associated with a higher a ( 20%) H-mode density lim…

Preprint Purchase
The published version of this paper is currently under embargo and will be available on 28/04/2022
2020
UKAEA-CCFE-PR(21)63

The optimum conditions for access to and sustainment of H-mode plasmas and their expected plasma parameters in the Pre-Fusion Power Operation 1 (PFPO-1) phase of the ITER Research Plan, where the additional plasma heating will be provided by 20 MW of Electron Cyclotron Heating (ECH), are assessed in order to identify key open R&D issues. The as…

Preprint
2019
UKAEA-CCFE-PR(20)18

It is demonstrated that tokamak plasma can be fuelled by pellets while simultaneously maintaining ELM suppression by external resonant magnetic perturbations (RMPs). Pellets are injected from vertical high field site and deposited at outer part of plasma cross section. Each pellet triggers benign MHD event followed by short lived ELM free phase. Th…

Preprint Published
2018

Access conditions for full suppression of edge localised modes (ELMs) by magnetic perturbations (MP) in low density high confinement mode (H-mode) plasmas are studied in the ASDEX Upgrade tokamak. The main empirical requirements for full ELM suppression in our experiments are: 1. The poloidal spectrum of the MP must be aligned for best plasma respo…

Published
2019
UKAEA-CCFE-PR(20)05

Resistive plasma response to the n = 1 (n is the toroidal mode number) RMP field is systematically investigated for a high-beta hybrid discharge on ASDEX Upgrade. Both linear and quasi-linear response are modelled using the MARS-F and MARS-Q codes, respectively. Linear response computations show a large internal kink response when the plasma centra…

Preprint Published
2019
UKAEA-CCFE-PR(19)18

A numerical survey of the plasma response in ASDEX Upgrade ELM control experiments is conducted, to clarify the role of triangularity in the suppression mechanism. The pedestal pressure increases with triangularity consistent with previous work [2], which modestly boosts the peeling response. However, the peeling response decreases with increasi…

Preprint Published
2018
UKAEA-CCFE-PR(18)69

The impact of the three-dimensional (3D) tokamak geometry from external magnetic perturbations (MPs) on the local edge stability has been examined in high confinement mode (H-mode) plasmas with edge localised modes (ELMs) in ASDEX Upgrade. The 3D geometry has been probed using rigidly rotating MP fields. The measured distortions of the plasma bound…

Preprint Published
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