19 research outputs found

    Gaia Early Data Release 3: the Galactic anticentre

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    Stars and planetary system

    Impact of nitrogen seeding on carbon erosion in the JET divertor

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    Nitrogen has been introduced in H-mode plasmas in JET in order to study its radiation cooling capability and impact on the erosion of divertor plasma-facing components made of carbon-fiber composites (CFC). Experiments in the ionizing plasma regime with low nitrogen injection show a reduction of the total carbon erosion in the divertor measured with the aid of optical spectroscopy on C(+). Though chemical sputtering by nitrogen takes place, identified by the appearance of CN B-X band emission, the additional carbon source is overcompensated by a reduction of regular sputtering by deuterium bombardment. Moderate plasma cooling associated with reduction of the sputtering yield and dilution of the CFC surface by nitrogen can be attributed to the favorable reduction of the carbon source

    Observations of multi-resonance effect in ELM control with magnetic perturbation fields on the JET tokamak

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    Relevance of collisionality in the transport model assumptions for divertor detachment multi-fluid modelling on JET

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    A revised formulation of the perpendicular diffusive transport model in 2D multi-fluid edge codes is proposed. Based on theoretical predictions and experimental observations a dependence on collisionality is introduced into the transport model of EDGE2D-EIRENE. The impact on time-dependent JET gas fuelled ramp-up scenario modelling of the full transient from attached divertor into the high-recycling regime, following a target flux roll over into divertor detachment, ultimately ending in a density limit is presented. A strong dependence on divertor geometry is observed which can mask features of the new transport model: a smoothly decaying target recycling flux roll over, an asymmetric drop of temperature and pressure along the field lines as well as macroscopic power dependent plasma oscillations near the density limit which had been previously observed also experimentally. The latter effect is strongest for scenarios with strike points on vertical targets and vanishes in case of asymmetric divertor configurations. (C) 2011 EURATOM. Published by Elsevier B.V. All rights reserved

    Recent JET experiments on Alfven eigenmodes with intermediate toroidal mode numbers: measurements and modelling of n=3 toroidal Alfven eigenmodes with the TAEFL code

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    Structural changes and distribution of accumulated tritium in the carbon based JET tiles

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    Interpretation of divertor Langmuir probe measurements during the ELMs at JET

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    Comparison between dominant NB and dominant IC heated ELMy H-mode discharges in JET

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