TY - JOUR
T1 - Understanding narrow SOL power flux component in COMPASS limiter plasmas by use of Langmuir probes
AU - Dejarnac, R.
AU - Stangeby, P. C.
AU - Goldston, Robert James
AU - Gauthier, E.
AU - Horacek, J.
AU - Hron, M.
AU - Kocan, M.
AU - Komm, M.
AU - Panek, R.
AU - Pitts, R. A.
AU - Vondracek, P.
N1 - Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2015/7/22
Y1 - 2015/7/22
N2 - 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.
AB - 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.
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U2 - 10.1016/j.jnucmat.2014.12.100
DO - 10.1016/j.jnucmat.2014.12.100
M3 - Article
AN - SCOPUS:84937738518
SN - 0022-3115
VL - 463
SP - 381
EP - 384
JO - Journal of Nuclear Materials
JF - Journal of Nuclear Materials
M1 - 48832
ER -