Characterising dust in JET with the new ITER-like wall

J.C. Flanagan, M. Sertoli, M. Bacharis, G.F. Matthews, P.C. De Vries, A. Widdowson, I.H. Coffey, G. Arnoux, B. Sieglin, S. Brezinsek, J.W. Coenen, S. Marsen, T. Craciunescu, A. Murari, D. Harting, A. Cackett, E. Hodille

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Abstract

Recent studies dedicated to the characterisation of in-vessel dust in JET with the new ITER-like wall (ILW) show that dust levels are orders of magnitude lower compared with the latter stages of the carbon-wall (CW) period and are decreasing with operational time. Less than 1 g of dust was recovered in a recent inspection, compared with more than 200 g of material recovered at the end of the JET-CW life. Recent inspection of the ILW shows low rates of re-deposition with only small areas of damage of a type likely to create particulate matter. Quantifiers from laser scattering techniques also indicate an order of magnitude reduction in dust relative to the JET-CW and show that the amount of dust mobilized after a disruption is proportional to the dynamic vessel forces. It is not possible to infer what fraction of dust (if any) might be created by disruptions. However, disruption mitigation is found to reduce the amount of dust seen after moderate disruptions by a factor of 4. Analysis of the transient impurity events (TIEs) associated with dust show that tungsten dominates. A significant contribution to TIEs is also seen from iron, nickel and chromium (probably from steel and Inconel components). The incidence of severe negative effects on operations from TIEs is found to be relatively rare, with <1% of ILW disruptions linked to TIEs. The evolution of the TIE rate closely follows changes in the laser scattering dust quantifiers; both trend downwards in time but peak during periods of higher disruption rate (thought to be primarily driven by the mobilization of existing dust).
Original languageEnglish
Article number014037
Pages (from-to)-
JournalPlasma Physics and Controlled Fusion
Volume57
Issue number1
DOIs
Publication statusPublished - 1 Jan 2015
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

Cite this

Flanagan, J. C., Sertoli, M., Bacharis, M., Matthews, G. F., De Vries, P. C., Widdowson, A., Coffey, I. H., Arnoux, G., Sieglin, B., Brezinsek, S., Coenen, J. W., Marsen, S., Craciunescu, T., Murari, A., Harting, D., Cackett, A., & Hodille, E. (2015). Characterising dust in JET with the new ITER-like wall. Plasma Physics and Controlled Fusion, 57(1), -. [014037]. https://doi.org/10.1088/0741-3335/57/1/014037