TY  - JOUR
AU  - Dittmar, T.
AU  - Loarer, T.
AU  - Drenik, A.
AU  - Bourdelle, C.
AU  - Brezinsek, S.
AU  - Desgranges, C.
AU  - Douai, D.
AU  - Fedorczak, N.
AU  - Guirlet, R.
AU  - Gunn, J.
AU  - Meyer, O.
AU  - Laguardia, L.
AU  - Tsitrone, E.
TI  - Long pulse D 2 and N 2 seeded discharges on the upper actively cooled tungsten divertor of WEST
JO  - Physica scripta
VL  - T171
SN  - 1402-4896
CY  - Stockholm
PB  - The Royal Swedish Academy of Sciences
M1  - FZJ-2021-01496
SP  - 014074 -
PY  - 2020
AB  - A series of L-mode discharges in upper single null configuration with more than 30 s duration were performed in the WEST tokamak with the strike line on actively cooled tungsten-coated divertor components. This series of discharges accumulated 20 min of plasma and a strike point fluence of $\approx 2\times {10}^{25}\,{{\rm{m}}}^{-2}$ in two days of operation in attached conditions. The discharges showed good density control, no tungsten accumulation and overall very benign thermal behaviour of the upper divertor. A subset of the discharges were seeded with nitrogen either in the divertor or midplane region to study plasma–wall interaction and associated ammonia formation in this weakly pumped scenario with all-tungsten plasma-facing components. While ammonia signals remained too weak for useful analysis, a strong dependence of nitrogen plasma penetration efficiency and residence time on the injection location was found. This hints towards a currently underestimated plasma-near nitrogen reservoir in these tokamak discharges in divertor configuration.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000546774400001
DO  - DOI:10.1088/1402-4896/ab753f
UR  - https://juser.fz-juelich.de/record/891411
ER  -