Journal Article

FZJ-2017-05300

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Ion target impact energy during Type I edge localized modes in JET ITER-like Wall

Guillemaut, C. (Corresponding author) ; Jardin, A. ; Horacek, J. ; Autricque, A. ; Arnoux, G. ; Boom, J.FZJ* ; Brezinsek, S.FZJ* ; Coenen, J. W. (Corresponding author)FZJ* ; De La Luna, E. ; Devaux, S. ; Eich, T. ; Giroud, C. ; Harting, D. ; Kirschner, A.FZJ* ; Lipschultz, B. ; Matthews, G. F. ; Moulton, D. ; O’Mullane, M. ; Stamp, M.

2015
IOP Publ. Bristol

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Please use a persistent id in citations: doi:10.1088/0741-3335/57/8/085006

Abstract: The ITER baseline scenario, with 500 MW of DT fusion power and Q = 10, will rely on a Type I ELMy H-mode, with ΔW = 0.7 MJ mitigated edge localized modes (ELMs). Tungsten (W) is the material now decided for the divertor plasma-facing components from the start of plasma operations. W atoms sputtered from divertor targets during ELMs are expected to be the dominant source under the partially detached divertor conditions required for safe ITER operation. W impurity concentration in the plasma core can dramatically degrade its performance and lead to potentially damaging disruptions. Understanding the physics of plasma-wall interaction during ELMs is important and a primary input for this is the energy of incoming ions during an ELM event. In this paper, coupled Infrared thermography and Langmuir Probe (LP) measurements in JET-ITER-Like-Wall unseeded H-mode experiments with ITER relevant ELM energy drop have been used to estimate the impact energy of deuterium ions (D+) on the divertor target. This analysis gives an ion energy of several keV during ELMs, which makes D+ responsible for most of the W sputtering in unseeded H-mode discharges. These LP measurements were possible because of the low electron temperature (Te) during ELMs which allowed saturation of the ion current. Although at first sight surprising, the observation of low Te at the divertor target during ELMs is consistent with the 'Free-Streaming' kinetic model which predicts a near-complete transfer of parallel energy from electrons to ions in order to maintain quasi-neutrality of the ELM filaments while they are transported to the divertor targets.

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Contributing Institute(s):

1. Plasmaphysik (IEK-4)
2. Zentralinstitut für Elektronik (ZEA-2)

Research Program(s):

1. 174 - Plasma-Wall-Interaction (POF3-174) (POF3-174)

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Database coverage:
Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; National-Konsortium ; Nationallizenz ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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