Open AccessFirst neutral beam experiments on Wendelstein 7-X
Author(s) -
W X Team,
S. Lazerson,
O. Ford,
S. Äkäslompolo,
S. Bozhenkov,
C. Slaby,
L. Vanó,
A. Spanier,
P. McNeely,
N. Rust,
D. Hartmann,
P. Zs. Pölöskei,
Birger Buttenschoゆ,
R. Burhenn,
N. Tamura,
R. Bussiahn,
Thomas Wegner,
M. Drevlak,
Y. Turkin,
K. Ogawa,
J. Knauer,
K. J. Brunner,
E. Pasch,
M. Beurskens,
H. Damm,
G. Fuchert,
P. Nelde,
Evan Scott,
N. Pablant,
A. Langenberg,
P. Traverso,
P. Valson,
U. Hergenhahn,
A. Pavone,
K. Rahbarnia,
T. Andreeva,
J. Schilling,
C. Brandt,
U. Neuner,
H. Thomsen,
N. Chaudhary,
U. Hoefel,
T. Stange,
G. Weir,
N. B. Marushchenko,
M. Jakubowski,
Adnan Ali,
Yu Gao,
H. Niemann,
A. Puig Sitjes,
R. Koenig,
R. Schroeder,
N. den Harder,
B. Heinemann,
C. Hopf,
R. Riedl,
R. C. Wolf,
G. Gantenbein,
M. Hüber,
S. Illy,
J. Jelonnek,
T. Kobarg,
R. Lang,
W. Leonhardt,
D. Mellein,
Daniel Papenfuß,
T. Scherer,
M. Thumm,
S. Wadle,
J. Weggen
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/ac121c
Subject(s) - stellarator , neutral beam injection , wendelstein 7 x , divertor , electron cyclotron resonance , beam (structure) , cyclotron , plasma , atomic physics , materials science , ion , physics , computational physics , optics , nuclear physics , tokamak , quantum mechanics
In the previous divertor campaign, the Wendelstein 7-X (W7-X) device injected 3.6 MW of neutral beam heating power allowing for the achievement of densities approaching 2 × 10 20 m −3 , and providing the first initial assessment of fast ion confinement in a drift optimized stellarator. The neutral beam injection (NBI) system on W7-X is comprised of two beam boxes with space for four radio frequency sources each. The 3.6 MW of heating reported in this work was achieved with two sources in the NI21 beam box. The effect of combined electron-cyclotron resonance heating (ECRH) and NBI was explored through a series of discharges varying both NBI and ECRH power. Discharges without ECRH saw a linear increase in the line-integrated plasma density, and strong peaking of the core density, over the discharge duration. The presence of 1 MW of ECRH power was found to be sufficient to control a continuous density rise during NBI operation. Simulations of fast ion wall loads were found to be consistent with experimental infrared camera images during operation. In general, NBI discharges were free from the presence of fast ion induced Alfvénic activity, consistent with low beam betas. These experiments provide data for future scenario development and initial assessment of fast-ion confinement in W7-X, a key topic of the project.