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  4. Heat flux analysis of Type-I ELM impact on a sloped, protruding surface in the JET bulk tungsten divertor
 
research article

Heat flux analysis of Type-I ELM impact on a sloped, protruding surface in the JET bulk tungsten divertor

Gaspar, J.
•
Coenen, J. W.
•
Corre, Y.
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December 1, 2018
Nuclear Materials And Energy

Tungsten (W) melting due to transient power loads, for example those delivered by edge localised modes (ELMs), is a major concern for next step fusion devices. A series of experiments has been performed on JET to investigate the dynamics of Type-I ELM-induced transient melting. Following initial exposures in 2013 of a W-lamella with sharp leading edge in the bulk W outer divertor, new experiments have been performed in 2016-2017 on a protruding W-lamella with a 15 degrees slope, allowing direct and spatially resolved (0.85 mm/pixel) observation of the top surface using the IR thermography system viewing from the top of the poloidal cross-section. Thermal and IR analysis have already been conducted assuming the geometrical projection of the parallel heat flux on the W-lamellas, thus ignoring the gyro-radius orbit of plasma particles. Although it is well justified during L-mode or inter-ELM period, the hypothesis becomes questionable during ELM when the ion Larmor radius is larger. The goal of this paper is to extend the previous analysis based on the forward approach to the H-mode discharges and investigate in particular the gyro-radius effect during the Type-I ELMs, those used to achieve transient melting on the slope of the protruding W-lamella. Surface temperatures measured by the IR camera are compared with reconstructed synthetic data from 3D thermal modelling using heat loads derived from optical projection of the parallel heat flux (ignoring the gyro-radius orbit), 2D gyro-radius orbit and particle-in-cell (PIC) simulations describing the influence of finite Larmor-radius effects and electrical potential on the deposited power flux. Results show that the ELM power deposition behaves differently than the optical projection of the parallel heat flux, contrary to the L-mode observations, and may thus be due to the much larger gyro-orbits of the energetic ELM ions in comparison to L-mode or inter-ELM conditions.

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Type
research article
DOI
10.1016/j.nme.2018.10.009
Web of Science ID

WOS:000454165000024

Author(s)
Gaspar, J.
Coenen, J. W.
Corre, Y.
Dejarnac, R.
Firdaouss, M.
Clairet, F.
Gunn, J.
Iglesias, D.
Komm, M.
Krieger, K.
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Date Issued

2018-12-01

Published in
Nuclear Materials And Energy
Volume

17

Start page

182

End page

187

Subjects

Nuclear Science & Technology

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elm heat flux analysis

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optical projection

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pic modelling

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ion orbit modelling

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ir data

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spatial resolution effect

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
SPC  
Available on Infoscience
September 20, 2019
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/161354
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