1. First neutral beam experiments on Wendelstein 7-X
- Author
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Uwe Hergenhahn, Christian Brandt, P. Valson, Wendelstein X Team, E. Pasch, M. W. Jakubowski, P. Pölöskei, Nikolai B. Marushchenko, Aleix Puig Sitjes, Kian Rahbarnia, Kunihiro Ogawa, Manfred Thumm, L. Vano, Bernd Heinemann, Wolfgang Leonhardt, Dirk Hartmann, D. Mellein, Jonathan Schilling, Jörg Weggen, R. Riedl, Tamara Andreeva, Daniel Papenfuß, Adnan Ali, C. Slaby, Rouven Lang, R. Schroeder, Samuel Lazerson, R. Burhenn, Michael Drevlak, Torsten Stange, Birger Buttenschoゆ, A. Spanier, John Jelonnek, R. C. Wolf, R. Koenig, S. Wadle, T. Wegner, Martina Huber, G. M. Weir, H. Thomsen, Kai Jakob Brunner, Yu Gao, G. Fuchert, P. McNeely, E. R. Scott, R. Bussiahn, P. Traverso, N. Chaudhary, Holger Niemann, Stefan Illy, Theo Scherer, H. Damm, Christian Hopf, S. A. Bozhenkov, Gerd Gantenbein, O. P. Ford, Andreas Langenberg, M. N. A. Beurskens, Simppa Äkäslompolo, Ulrich Neuner, Yuriy Turkin, Naoki Tamura, Andrea Pavone, J. P. Knauer, Niek den Harder, Thorsten Kobarg, N. A. Pablant, U. Hoefel, N. Rust, Philipp Nelde, Department of Applied Physics, Aalto-yliopisto, Aalto University, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
- Subjects
Physics ,Nuclear and High Energy Physics ,Technology ,Fast ions ,Condensed Matter Physics ,01 natural sciences ,Neutral beam ,010305 fluids & plasmas ,law.invention ,Nuclear physics ,law ,0103 physical sciences ,Energetic particles ,Wendelstein 7-X ,010306 general physics ,Fusion ,ddc:600 ,Stellarator ,Beam (structure) - Abstract
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 × 1020 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.
- Published
- 2021