Wall conditioning in ASDEX Upgrade

V. Rohde, R. Dux, A. Kallenbach, K. Krieger, R. Neu

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

An overview on wall conditioning in ASDEX Upgrade is presented. Helium glow discharges (HeGD) are needed mostly for plasma start up after high density discharges, disruptions and disruption mitigation gas puffs. Boronisation is routinely applied. The reduction of the oxygen content is a minor effect. Strong variation of the wall pumping is observed for tungsten first wall materials. The uncoated tungsten surface stores and releases large amounts of He, which can disturb the plasma. The released He causes the modification in the wall pumping. By reducing HeGD this effect could be minimized. Advanced and natural density scenarios are sensitive to the status of the wall coating. Accumulation of impurities at the pedestal influences the ELM frequency and finally causes radiation unstable discharges.

Original languageEnglish
Pages (from-to)1369-1374
Number of pages6
JournalJournal of Nuclear Materials
Volume363-365
Issue number1-3
DOIs
StatePublished - 15 Jun 2007
Externally publishedYes

Keywords

  • ASDEX Upgrade
  • Boronisation
  • Gas injection and fueling
  • Wall conditioning
  • Wall pumping

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