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UKAEA-CCFE-PR(25)3862025
In high performance regimes short (sub ms) bursts of heat and particles from the core (edge localised modes, ELMs) happen cyclically increasing temporarily the heat flux by 2-3 orders of magnitude, and this can hardly be tolerated by large tokamaks. If ELMs happen when the target is detached the plasma temporarily reattaches and looses energy in th…
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UKAEA-CCFE-PR(25)3692024
Plasma detachment in tokamaks is useful for reducing heat flux to the target. It involves interactions of the plasma with impurities and neutral particles, leading to significant losses of plasma power, momentum, and particles. Accurate mapping of plasma emissivity in the divertor and X-point region is essential for assessing the rel…
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UKAEA-CCFE-PR(25)3112024
2D electron density profiles obtained from coherence imaging spectroscopy in different MAST-U divertor conditions are compared. The data includes variations of strike point position, core electron density, and heating power. The improved performance of the long-legged divertors results in a lower electron density and particle flux at the target …
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UKAEA-STEP-PR(24)182024
This paper presents a comprehensive overview of the preliminary divertor design and plasma exhaust scenario for the reactor-class Spherical Tokamak for Energy Production (STEP) project. Due to the smaller size of the machine, with a major radius less than half that of most DEMO concepts, the current design features a double-null divertor geometr…
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UKAEA-CCFE-PR(23)1632023
High resolution D2 Fulcher band spectroscopy was used in the MAST-U divertors during Super-X and elongated conventional divertor density ramps with D2 fuelling from the mid-plane high-field side. In the Super-X case (density ramp from Greenwald fraction 0.12 to 0.24), the upper divertor showed ground state rotational tempe…
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UKAEA-CCFE-PR(23)1322023
First quantitative analysis of the detachment processes in the MAST Upgrade Super-X divertor show an unprecedented impact of plasma-molecular interactions involving molecular ions (likely $D_2^+$), resulting in strong ion sinks, leading to a reduction of ion target flux. This starts to occur as the ionisation source detaches from the target, lea…
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UKAEA-CCFE-PR(23)112023
A prototype infrared video bolometer (IRVB) was succesfully deployed in MAST-U, the first deployment of such a diagnostic in spherical tokamaks. The IRVB was designed to study the radiation around the x-point and has the potential to return emissivity profiles of unprecedented spatial resolution. The system was fully characterised prior installatio…
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UKAEA-CCFE-PR(25)2802022
In this work a spatial dimension is added to the description of radiative detachment in MAST-U super-X divertor plasmas. This magnetic configuration is hypothesized to achieve improved heat load spreading at the divertor target and more particle-, heat- and momentum losses through plasma-neutral interactions than conventional exhaust solutions. Fil…
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UKAEA-STEP-PR(23)072022
To mitigate the issue of plasma exhaust in reactor scale tight aspect ratio tokamaks such as STEP (Spherical Tokamak for Energy Production), a double-null (DN) configuration is thought to be advantageous over a single-null (SN) configuration. However, practical control of the plasma vertical stability will likely lead to an oscillation around th…
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UKAEA-CCFE-PR(23)942022
Divertor detachment requires plasma-neutral interactions which dissipate momentum, power and particles simultaneously. Plasma-molecular interactions can result in molecular ions which react with the plasma. This can contribute to detachment through molecular activated recombination (MAR) and molecular activated dissociation (MAD), both of which cre…
Showing 1 - 10 of 40 UKAEA Paper Results