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UKAEA-CCFE-PR(23)1582023
We propose a resistivity-beta driving mechanism aimed at explaining the appearance of free boundary long wavelength global instabilities in high-beta diverted tokamaks. These perturbations resemble very closely the RWM (resistive wall mode) phenomenon. Performing a proper toroidal analysis, we show that the magnetohydrodynamic stability is worsened…
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UKAEA-CCFE-PR(23)1202023
External kink modes, believed to be the drive of the beta-limiting Resistive Wall Mode, are strongly mitigated by the presence of a separatrix. We thus propose a novel mechanism explaining the appearance of long-wavelength global instabilities in free boundary high-beta diverted tokamaks, retrieving the experimental observables within a physical…
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UKAEA-CCFE-PR(22)052022
The analysis of quiescent discharges exhibiting edge harmonic magnetoydrodynamic activity in the JET-Carbon wall machine is presented. It is observed that the quiescent phase with multiple-n harmonic oscillations is sustained until a threshold in pedestal electron density and collisionality is crossed. The macroscopic pedestal parameters associated…
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UKAEA-CCFE-PR(21)812021
The impact of plasma shaping through magnetic well modifications on the stability of resistive ballooning modes in tokamaks is analysed, also including finite diamagnetic flows. Various limiting cases of the dispersion relation, obtained by matching the averaged ballooning equation across the ideal and resistive layers, are analysed. It is found th…
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UKAEA-CCFE-CP(21)082021
The pedestal plays an important role in determining the confinement in tokamak H-mode plasmas. However, the steep pressure gradients in this transport barrier also lead to edge localized modes (ELMs) [1]. There is good understanding of the pedestal in type I ELM regimes [2], however, type I ELMs are known to damage plasma facing components and f…
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UKAEA-CCFE-PR(21)372021
This work presents an extension of exfernal mode theory where the effects of edge magnetic shear and plasma separatrix are investigated., from which a set of three coupled differential equations describing the dispersion relation are derived. To correctly assess the effect of edge shear on exfernal modes, higher order corrections need to be retaine…
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UKAEA-CCFE-PR(21)312021
This paper is part of a series of publications concerning the development of the European DEMO during the pre- conceptual design phase (2014-2020). In particular, it deals with the physics basis employed for the definition of the various DEMO baselines released, and …
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UKAEA-CCFE-PR(20)772020
Anisotropy and some limiting toroidal flow effects on the stability of non resonant ideal magnetohydrodynamic modes in hybrid shaped tokamak plasmas are investigated within the ideal MHD infernal mode framework. Such effects are found to alter the plasma magnetic well/hill, which can be interpreted as imparing the average curvature, and the stre…
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UKAEA-CCFE-CP(20)1022018
The JET exploitation plan foresees D-T operations in 2019-2020. With respect to the first D-T campaign in 1998, when JET was equipped with a carbon wall, the experiments will be conducted in presence of a beryllium-tungsten ITER-like wall and will benefit from an extended and improved set of diagnostics and higher available additional heating power…
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UKAEA-CCFE-PR(19)752019
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…
Showing 1 - 10 of 29 UKAEA Paper Results