Conference Papers

Showing 1 - 8 of 8 Conference Paper Results
2020
UKAEA-CCFE-CP(20)71
27th IAEA Fusion Energy Conference, Ahmedabad, India, 22-27 October 2018

The fast-ion transport has been investigated in low-collisionality discharges at ASDEX Upgrade and TCV using offaxis neutral beams. In both devices Alfven eigenmode activity was observed which does, however, not strongly affect the global fast-ion confinement. In contrast, charge exchange losses have been identified to have a strong effect. At TCV …

Preprint
2020
UKAEA-CCFE-CP(20)91
14th International Reflectometry Workshop, Swiss Plasma Center of the Ecole Polytechnique Fédérale de Lausanne, Switzerland, 22-24 May 2019

The experimental validation of turbulence models is a critical part of developing a predictive understanding of plasma transport. Models based on the non-linear gyrokinetic equations are currently the most well understood and experimentally validated models of turbulence available. However, models of reduced complexity are required in order to mak…

Preprint Published
2019
UKAEA-CCFE-CP(19)28
27th IAEA Fusion Energy Conference, Ahmedabad, India, 22-27 October 2018

A detailed cross-device investigation on the role of filamentary dynamics in high density regimes has been performed within the EUROfusion framework comparing ASDEX-Upgrade (AUG) and TCV tokamaks. Both devices have run density ramp experiments at different levels of plasma current, keeping toroidal field or q95 constant in order to disentangle the …

Preprint Published
2019
UKAEA-CCFE-CP(19)20
23rd International Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI), Princeton, NJ, USA, 17-22 June 2018

Reducing the plasma power exhaust impacting on plasma facing components during steady state operation is one of the major design issues in future tokamaks such as ITER. Impurity seeding, e.g. with N, is one method of achieving this and has been used for a long time in tokamak research [1]. In this work we exploit a recently developed spectroscopic …

Preprint Published
2019
UKAEA-CCFE-CP(19)16
45th European Physical Society Conference on Plasma Physics (EPS), Prague, 2-6 July 2018

Edge Localised Modes (ELMs) in H-mode tokamak plasmas may be controlled or entirely suppressed by applying 3D magnetic perturbations (MPs). The applied perturbation is amplified by the plasma response, and it has previously been established that the size of the peeling component of this response is a reliable indicator for expected ELM control on A…

Preprint
2019
UKAEA-CCFE-CP(19)11
22nd Topical Conference on High Temperature Plasma Diagnostics (HTPD), San Diego, USA, 16-19 April 2018

Ion cyclotron emission (ICE) is a commonly observed feature of magnetized toroidal plasmas in the presence of fast ions. It is generally agreed that this emission is caused by a strongly inverted (in the velocity space) population of confined fast ions originating from either neutral beam injection (NBI), fusion reactions, or acceleration by waves …

Preprint Published
2018
UKAEA-CCFE-CP(18)05
45th European Physical Society Conference on Plasma Physics (EPS), Prague, 2-6 July 2018

Pellets are used in ASDEX Upgrade [1] to control plasma density under conditions of ELM control or divertor detachment. In experiments presented here direct fuelling by gas is negligible. Relative pellet size and pellet deposition are aimed to approach those in ITER but differences still remain. ELMs are controlled by n=2 RMPs in feed forward mode …

Preprint
2018
UKAEA-CCFE-CP(18)04
27th IAEA Fusion Energy Conference, Ahmedabad, India, 22-27 October 2018

An edge resonant transport layer has been found to explain many aspects of fast-ion confinement under symmetry breaking 3D edge perturbations, such as edge localized modes (ELMs) and externally applied magnetic perturbations (MPs). Experimental measurements in the ASDEX Upgrade (AUG) tokamak show that fast-ion losses in the presence of symmetry bre…

Preprint Published