First neutral beam experiments on Wendelstein 7-X

Team, W X; Lazerson, S.; Ford, O.; Äkäslompolo, S.; Bozhenkov, S.; Slaby, C.; Vanó, L.; Spanier, A.; McNeely, P.; Rust, N.; Hartmann, D.; Pölöskei, P. Zs.; Buttenschoゆ, Birger; Burhenn, R.; Tamura, N.; Bussiahn, R.; Wegner, Thomas; Drevlak, M.; Turkin, Y.; Ogawa, K.; Knauer, J.; Brunner, K. J.; Pasch, E.; Beurskens, M.; Damm, H.; Fuchert, G.; Nelde, P.; Scott, Evan; Pablant, N.; Langenberg, A.; Traverso, P.; Valson, P.; Hergenhahn, U.; Pavone, A.; Andreeva, T.; Schilling, J.; Brandt, C.; Neuner, U.; Thomsen, H.; Chaudhary, N.; Hoefel, U.; Stange, T.; Weir, G.; Marushchenko, N. B.; Jakubowski, M.; Ali, Adnan; Gao, Yu; Niemann, H.; Sitjes, A. Puig; Koenig, R.; Schroeder, R.; Harder, N. den; Heinemann, B.; Hopf, C.; Riedl, R.; Wolf, R. C.; Gantenbein, G.; Hüber, M.; Illy, S.; Jelonnek, J.; Kobarg, T.; Lang, R.; Leonhardt, W.; Mellein, D.; Papenfuß, Daniel; Scherer, T.; Thumm, M.; Wadle, S.; Weggen, J.

doi:10.1088/1741-4326/ac121c

Cited by 22 publications

(17 citation statements)

References 25 publications

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“…NBI operation also provides a chance to fuel the plasma centrally. High core densities in W7-X were achieved through 3.6 MW of neutral beam injection heating, with no ECRH [42]. These discharges reached core densities of 2 × 10 20 m −3 with Figure 4.…”

Section: Nbi Operation and Peaked Density Profilesmentioning

confidence: 82%

“…In figure 7, they do not stand out as having improved confinement, but it should be cautioned that their triple products are likely underestimated, since port losses, shine-through, and fast ion losses were not taken into account when calculating their confinement times. Neutral beam power deposition simulations are still undergoing validation [41,42]. NBI results are discussed also in section 5.…”

Section: High-performance Discharges and Proof Of Neoclassical Optimi...mentioning

confidence: 99%

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Experimental confirmation of efficient island divertor operation and successful neoclassical transport optimization in Wendelstein 7-X

Pedersen

2022

Nucl. Fusion

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We present recent highlights from the most recent operation phases of Wendelstein 7-X, the most advanced stellarator in the world. Stable detachment with good particle exhaust, low impurity content, and energy confinement times exceeding 100 ms, have been maintained for tens of seconds. Pellet fueling allows for plasma phases with reduced ITG turbulence, and during such phases, the overall confinement is so good (energy confinement times often exceeding 200 ms) that the attained density and temperature profiles would not have been possible in less optimized devices, since they would have had neoclassical transport losses exceeding the heating applied in W7-X. This provides proof that the reduction of neoclassical transport through magnetic field optimization is successful. W7-X plasmas generally show good impurity screening and high plasma purity, but there is evidence of longer impurity confinement times during turbulence-suppressed phases.

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Section: Nbi Operation and Peaked Density Profilesmentioning

confidence: 82%

Section: High-performance Discharges and Proof Of Neoclassical Optimi...mentioning

confidence: 99%

Experimental confirmation of efficient island divertor operation and successful neoclassical transport optimization in Wendelstein 7-X

Pedersen

2022

Nucl. Fusion

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“…Generation of an active dFIS signal within 10 ms after interlock event: temperature of a divertor module is too high is occurred, ECRH 1 [9] (aFIS) Switch off of all gyrotrons within 5µs. NBI20 2 /NBI21 1 [10] (aFIS)…”

Section: A System Overview Of Fismentioning

confidence: 99%

Enhancements of the Fast Interlock System for Wendelstein 7-X Operational Phase OP 2.1

Schacht

Vilbrandt

Degenkolbe

et al. 2023

IEEE Trans. Nucl. Sci.

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An extended modification phase of the superconducting fusion experiment Wendelstein 7-X was completed late 2021 after installing actively cooled divertor units and the integration or modification of new technical components and diagnostics. Currently, the commissioning of the W7-X experiment is underway. First technical plasma operation is scheduled for the end of September 2022, and scientific plasma operation will start at the end of November.The Fast Interlock System (FIS) is an important component of the Safety Instrumented System (SIS) of W7-X. The main task of the FIS is to protect the inner plasma vessel components from thermal overload from both plasma heating systems (e.g. neutral beam injection) and the plasma itself. There are strict limits for reaction times after detection of interlock relevant events, which have to be observed in order to prevent overload situations of the first wall.The requirements for the FIS were substantially modified and extended, in order to address the challenges due to the actively cooled divertor. This led to extensive revision of the technical implementation and the software of the FIS.In this paper, after a short introduction of FIS design and operation in OP1, the modification of FIS for OP2.1 operation is presented. Finally, the first results during the OP2.1 commissioning and operation of the FIS are discussed.

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“…A study of the energetic ion loss process was performed using a FILD in the middle-sized stellarators and heliotrons [27][28][29][30][31]. Additionally, an energetic particle physics study in the W7-X was initiated using NB in 2018 [32] and will be advanced using FILD [33,34]. To date, a study of energetic ion transport/loss due to energetic-particle-driven MHD instability has been led in the LHD [35] based on intensive NB injectors [36].…”

Section: Introductionmentioning

confidence: 99%

Studies of energetic particle transport induced by multiple Alfvén eigenmodes using neutron and escaping energetic particle diagnostics in Large Helical Device deuterium plasmas

et al. 2022

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Studies of energetic particle transport due to energetic-particle-driven Alfvénic instability have progressed using neutron and energetic particle diagnostics in Large Helical Device deuterium plasmas. Alfvénic instability excited by injecting an intensive neutral beam was observed by a magnetic probe and a far-infrared laser interferometer. The interferometer showed Alfvénic instability composed of three modes that existed from the core to the edge of the plasma. A comparison between the observed frequency and shear Alfvén spectra suggested that the mode activity was most likely classified as an Alfvénic avalanche. A neutron fluctuation detector and a fast ion loss detector indicated that Alfvénic instability induced transport and loss of co-going transit energetic ions. The dependence of the drop rate of the neutron signal on the Alfvénic instability amplitude showed that significant transport occurred. Significant transport might be induced by the large amplitude and radially extended multiple modes, as well as a large deviation of the energetic ion orbit from the flux surface.

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First neutral beam experiments on Wendelstein 7-X

Cited by 22 publications

References 25 publications

Experimental confirmation of efficient island divertor operation and successful neoclassical transport optimization in Wendelstein 7-X

Experimental confirmation of efficient island divertor operation and successful neoclassical transport optimization in Wendelstein 7-X

Enhancements of the Fast Interlock System for Wendelstein 7-X Operational Phase OP 2.1

Studies of energetic particle transport induced by multiple Alfvén eigenmodes using neutron and escaping energetic particle diagnostics in Large Helical Device deuterium plasmas

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