Long-term fuel retention and release in JET ITER-Like Wall at ITER-relevant baking temperatures

Kalle Heinola, Jari Likonen, Tommy Ahlgren, Sebastijan Brezinsek, Gregory De Temmerman, Ionut Jepu, Guy Matthews, Pichard Pitts, Anna Widdowson

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Abstract

The fuel outgassing efficiency from plasma-facing components exposed in JET-ILW has been studied at ITER-relevant baking temperatures. Samples retrieved from the W divertor and Be main chamber were annealed at 350 and 240 °C, respectively. Annealing was performed with thermal desoprtion spectrometry (TDS) for 0, 5 and 15 h to study the deuterium removal effectiveness at the nominal baking temperatures. The remained fraction was determined by emptying the samples fully of deuterium by heating W and Be samples up to 1000 and 775 °C, respectively. Results showed the deposits in the divertor having an increasing effect to the remaining retention at temperatures above baking. Highest remaining fractions 54 and 87% were observed with deposit thicknesses of 10 and 40 μm, respectively. Substantially high fractions were obtained in the main chamber samples from the deposit-free erosion zone of the limiter midplane, in which the dominant fuel retention mechanism is via implantation: 15 h annealing resulted in retained deuterium higher than 90%. TDS results from the divertor were simulated with TMAP7 calculations. The spectra were modelled with three deuterium activation energies resulting in good agreement with the experiments.

Original languageEnglish
Article number086024
JournalNuclear Fusion
Volume57
Issue number8
DOIs
Publication statusPublished - 30 Jun 2017
MoE publication typeA1 Journal article-refereed

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Keywords

  • fuel retention
  • ITER
  • deposition
  • divertor
  • main chamber
  • JET-ILW

Cite this

Heinola, K., Likonen, J., Ahlgren, T., Brezinsek, S., De Temmerman, G., Jepu, I., Matthews, G., Pitts, P., & Widdowson, A. (2017). Long-term fuel retention and release in JET ITER-Like Wall at ITER-relevant baking temperatures. Nuclear Fusion, 57(8), [086024]. https://doi.org/10.1088/1741-4326/aa747e