Ion target impact energy during Type I edge localized modes in JET ITER-like Wall - Archive ouverte HAL
Article Dans Une Revue Plasma Physics and Controlled Fusion Année : 2015

Ion target impact energy during Type I edge localized modes in JET ITER-like Wall

Stéphane Devaux
B. Lipschultz
  • Fonction : Auteur

Résumé

The ITER baseline scenario, with 500 MW of DT fusion power and Q = 10, will rely on a Type I ELMy H-mode, with Delta W = 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 (T-e) during ELMs which allowed saturation of the ion current. Although at first sight surprising, the observation of low T-e 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.

Dates et versions

hal-01285773 , version 1 (09-03-2016)

Identifiants

Citer

C. Guillemaut, A. Jardin, J. Horacek, A. Autricque, G. Arnoux, et al.. Ion target impact energy during Type I edge localized modes in JET ITER-like Wall. Plasma Physics and Controlled Fusion, 2015, 57 (8), ⟨10.1088/0741-3335/57/8/085006⟩. ⟨hal-01285773⟩
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