Open AccessOverview of the results from divertor experiments with attached and detached plasmas at Wendelstein 7-X and their implications for steady-state operation
Author(s) -
M. Jakubowski,
M. Endler,
Y. Feng,
Yu Gao,
C. Killer,
R. König,
M. Krychowiak,
V. Perseo,
F. Reimold,
O. Schmitz,
T. S. Pedersen,
S. Brezinsek,
A. Dinklage,
P. Drewelow,
H. Niemann,
M. Otte,
M. Gruca,
Kenneth Hammond,
T. Kremeyer,
M. Kubkowska,
Sławomir Jabłoński,
Arun Pandey,
G. A. Wurden,
D. Zhang,
S. Bozhenkov,
D. Böckenhoff,
C. P. Dhard,
J. Baldzuhn,
D. Gradic,
F. Effenberg,
P. Kornejew,
S. Lazerson,
J. Lore,
D. Naujoks,
A. Puig Sitjes,
G. Schlisio,
M. Ślȩczka,
U. Wenzel,
V. Winters
Publication year - 2021
Publication title -
nuclear fusion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.774
H-Index - 120
eISSN - 1741-4326
pISSN - 0029-5515
DOI - 10.1088/1741-4326/ac1b68
Subject(s) - divertor , stellarator , plasma , wendelstein 7 x , nuclear engineering , steady state (chemistry) , materials science , mechanics , particle (ecology) , heat flux , power (physics) , physics , atomic physics , computational physics , nuclear physics , tokamak , thermodynamics , chemistry , heat transfer , engineering , oceanography , geology
Wendelstein 7-X (W7-X), the largest advanced stellarator, is built to demonstrate high power, high performance quasi-continuous operation. Therefore, in the recent campaign, experiments were performed to prepare for long pulse operation, addressing three critical issues: the development of stable detachment, control of the heat and particle exhaust, and the impact of leading edges on plasma performance. The heat and particle exhaust in W7-X is realized with the help of an island divertor, which utilizes large magnetic islands at the plasma boundary. This concept shows very efficient heat flux spreading and favourable scaling with input power. Experiments performed to overload leading edges showed that the island divertor yields good impurity screening. A highlight of the recent campaign was a robust detachment scenario, which allowed reducing power loads even by a factor of ten. At the same time, neutral pressures at the pumping gap entrance yielded the particle removal rate close to the values required for stable density control in steady-state operation.