Modelling of deposition and erosion of injected WF6 and MoF6 in TEXTOR

the TEXTOR team

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Tracer injection experiments in TEXTOR with MoF6 and WF6 lead to local deposition of about 6% for Mo and about 1% for W relative to the injected amount of Mo and W atoms. Modelling of these experiments has been done with ERO applying updated data for physical sputtering. The dissociation of the injected molecules has been treated in a simplified manner due to the lack of dissociation rate coefficients. However, with this it was possible to reproduce the observed radial penetration of Mo and W atoms into the plasma. The modelled local deposition efficiencies are about 50% for Mo and 60% for W assuming typical plasma parameters for the experimental conditions used. To reproduce the measured deposition efficiencies an enhancement factor for the erosion of deposited Mo and W has to be assumed (∼10 for Mo and ∼25 for W). Due to the rather low electron temperature Te of these plasma conditions (Te∼15 eV at the location of injection), Mo and W are mostly sputtered by impurities whereas sputtering due to deuterium is negligible. A parameter study applying larger electron temperature leads to increased sputtering and thus to reduced local deposition efficiencies of about 30% for Mo and 5% for W. Though, even under these conditions enhanced erosion, albeit with reduced enhancement factors, is needed in the modelling to obtain the small measured deposition efficiencies.

Original languageEnglish
Pages (from-to)564-568
Number of pages5
JournalNuclear Materials and Energy
Volume12
DOIs
StatePublished - Aug 2017
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2016 The Authors

Keywords

  • 52.40.Hf
  • 52.65.Pp
  • 52.77.Dq
  • Erosion & Deposition
  • Impurity transport
  • Sputtering
  • TEXTOR

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