Understanding narrow SOL power flux component in COMPASS limiter plasmas by use of Langmuir probes

R. Dejarnac, P. C. Stangeby, Robert James Goldston, E. Gauthier, J. Horacek, M. Hron, M. Kocan, M. Komm, R. Panek, R. A. Pitts, P. Vondracek

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Abstract The narrow scrape-off layer power component observed in COMPASS inner wall limiter circular discharges by means of IR thermography is investigated by Langmuir probes embedded in the limiter. The power flux profiles are in good agreement with IR observations and can be described by a double-exponential decay with a short decay length (<5 mm) just outside the separatrix and a longer one (∼50 mm) for the rest of the profile in the main scrape-off layer. Non-ambipolar currents measured at the limiter apex play a relatively modest role in the formation of the narrow component. The fraction of the deposited power due to non-ambipolarity varies between 2% and 45%. On the other hand, the measured power widths are roughly consistent in magnitude with a model that takes into account drift effects, suggesting these effects may be dominant.

Original languageEnglish (US)
Article number48832
Pages (from-to)381-384
Number of pages4
JournalJournal of Nuclear Materials
StatePublished - Jul 22 2015

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • General Materials Science
  • Nuclear Energy and Engineering


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