Time-resolved deposition in the remote region of the JET-ILW divertor: Measurements and modelling

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Abstract

One crucial requirement for the development of fusion power is to know where, and how much, impurities collect in the machine, and how much of the fuelling isotope tritium will be trapped therein. The most relevant information on this issue comes from the operation of the Joint European Tokamak (JET), which is the world's largest operating tokamak and has the same interior plasma-facing materials as the next step machine, ITER. Much of the information gained so far has been from post-mortem analysis of samples collected after whole campaigns involving varied types of operation. This paper describes time-resolved measurements of the deposition rate using rotating collectors (RC) placed in remote areas of the JET divertor during the 2013-2014 campaign with the ITER-like Wall (ILW). These techniques allow the effects of different types of operation to be distinguished. Rotating collectors made of silicon discs housed behind an aperture are exposed to the plasma. Each time the magnetic field coils are ramped up for a discharge the disc rotates, providing a linear relationship between the exposed region and the discharge number. Post-mortem ion beam analyses provide information on the deposit composition as a function of the discharge number. The results show that the Be deposition average for the RC in the corners of the inner and outer divertor are 4.9 × 1016 cm-2 and 1.8 × 1017 cm-2, respectively, accumulated over an average of ∼25 pulses. Data from the rotating collector below Tile 5 in the central region of divertor indicate a Be deposition rate of 9.3 × 1015 cm-2, per ∼25 pulses.

Original languageEnglish
Article number014059
JournalPhysica Scripta
Volume2017
Issue numberT170
DOIs
StatePublished - 1 Dec 2017
Event16th International Conference on Plasma-Facing Materials and Components for Fusion Applications, PFMC 2017 - Neuss/Dusseldorf, Germany
Duration: 16 May 201719 May 2017

Keywords

  • Beryllium
  • Deposition
  • JET divertor
  • Sputtering

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