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UKAEA-CCFE-CP(19)202019
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 …
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UKAEA-CCFE-CP(19)162019
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…
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UKAEA-CCFE-PR(19)182019
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…
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UKAEA-CCFE-CP(18)052018
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 …
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UKAEA-CCFE-CP(18)042018
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…
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UKAEA-CCFE-PR(18)692018
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…
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UKAEA-CCFE-PR(18)542018
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 …
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UKAEA-CCFE-PR(18)232018
Ray-tracing techniques are applied to bolometry, a diagnostic particularly sensitive to machine geometry due to the effect of volume sampling. Sightlines from the ASDEX-Upgrade bolometer foils were ray-traced with a path tracing algorithm, where the optical path is represented by a statistical bundle of ray paths connecting the foil surface with th…
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CCFE-PR(17)702017
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 …
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CCFE-PR(17)482017
The ITER tokamak needs to sustain a plasma in a regime of high energy confinement (H-mode) to exceed fusion breakeven where power output exceeds input. H-mode plasmas are typically unstable to edge localised modes (ELMs), in which plasma escapes and strikes the plasma facing components. Scaled up to ITER, the energy released by ELMs can cause criti…
Showing 21 - 30 of 52 UKAEA Paper Results