First neutral beam experiments on Wendelstein 7-X
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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2021-09
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Language
en
Pages
7
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Nuclear Fusion, Volume 61, issue 9
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 MWof 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 Alfvenic 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 EURATOM 2021.Description
| openaire: EC/H2020/633053/EU//EUROfusion
Keywords
Energetic particles, Fast ions, Fusion, Neutral beam, Stellarator
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Citation
W7-X Team 2021, ' First neutral beam experiments on Wendelstein 7-X ', Nuclear Fusion, vol. 61, no. 9, 096008 . https://doi.org/10.1088/1741-4326/ac121c