Validating the ASCOT modelling of NBI fast ions in Wendelstein 7-X stellarator

Äkäslompolo, S.; Drewelow, P.; Gao, Yu; Ali, Adnan; Biedermann, C.; Bozhenkov, S.; Dhard, C. P.; Endler, M.; Fellinger, J.; Ford, O.; Geiger, B.; Geiger, J.; Harder, N. den; Hartmann, D.; Hathiramani, D.; Isobe, M.; Jakubowski, M.; Kazakov, Ye. O.; Killer, C.; Lazerson, S.; Mayerd, M.; McNeely, P.; Naujoks, D.; Neelis, T. W. C.; Kontula, J.; Kurki-Suonio, T.; Niemann, H.; Ogawa, K.; Pisano, F.; Pölöskei, P. Zs.; Sitjes, A. Puig; Rust, N.; Schmitt, J. C.; Ślęczka, M.; Vanó, L.; Vuuren, A. van; Wurden, G. A.; Wolf, R. C.; Team, W X

doi:10.1088/1748-0221/14/10/c10012

Cited by 21 publications

(17 citation statements)

References 11 publications

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“…Experiments began with injection into plasmas sustained by electron cyclotron resonance heating (ECRH), allowing for control of target plasmas and densities. These experiments provided a wealth of information to help validated both neutral beam deposition [3] and wall loss estimates [4]. Discharges heated solely by neutral beam injection (NBI) were also demonstrated.…”

Section: Introductionmentioning

confidence: 93%

First neutral beam experiments on Wendelstein 7-X

Team¹,

Lazerson²,

Ford³

et al. 2021

Nucl. Fusion

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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

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Section: Introductionmentioning

confidence: 93%

First neutral beam experiments on Wendelstein 7-X

Team¹,

Lazerson²,

Ford³

et al. 2021

Nucl. Fusion

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“…As a result, the NBI-experiments, plasmas were performed without inward shift in the high-mirror or the standard configuration. The fast ion losses have been visible, but with relatively low loads, not harming the device [27].…”

Section: ) Ascot Modelling Was Used To Determine the Fast Lossesmentioning

confidence: 98%

Operation of W7-X With an Inertially Cooled Divertor—On the Way to Steady State Operation

Bosch

Äkäslompolo

Brakel

et al. 2020

IEEE Trans. Plasma Sci.

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The superconducting stellarator Wendelstein 7-X has completed the first three experiment phases, the first one with a limiter only and two phases with an inertially cooled carbon divertor configuration. The main mission of the latter two phases (the last one with two scraper elements) was to pave the way for the planned steady state-operation with high power plasmas and a steady-state divertor. Presently, the device is being completed by installing a High-Heat-Flux (HHF) divertor, the corresponding water-cooling and ten cryo pumps in the divertor chambers. After this completion phase of W7-X the device is ready for long pulse divertor operation with heating power beyond 10 MW.

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“…The simulations utilized accurate experiment geometry for the NBI injectors, magnetic field and plasma-facing components and followed NBI injected fast ions from ionization, through the slowing down process, until cooled down to thermal energy or hitting the wall. The simulation results showed, firstly, that only the molten holder received significant heat load from NBI orbit losses, and, secondly, the load was high only in the simulation of the standard configuration [16]. Figure 9 presents results from these simulations, and they are to be perceived as typical values for various NBI experiments during the campaign, not for quantitative assessment of this particular melting event: the investigated plasma shot #20180918.040 was fueled with H2 and heated with ECRH (5.52 MW) and NBI (1.8 MW).…”

Section: Wafer Probe Holdermentioning

confidence: 99%

Inspection of W 7-X plasma-facing components after the operation phase OP1.2b: observations and first assessments

et al. 2020

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Due to its twisted magnetic field configurations, the orientation of the plasma-facing components of the Wendelstein 7-X stellarator is changed from bean shape to triangular shape along the plasma axis within a module. The plasma-facing components consist of graphite (test divertor units, baffles, head shield tiles, toroidal divertor closures) and stainless steel components (wall panels, pumping gap panels, poloidal closures). In order to document the status of these components as well as to get the first footprints of the plasma-wall interactions that occurred during the plasma campaign, a detailed inspection of the whole plasma vessel after the plasma campaign is of vital importance. Such an inspection was carried out after the operation phase OP1.2b completed in October 2018. A number of observations were made, such as, molten stainless steel drops, melting of a long term probe, deposition on steel panels, arc traces, loosely bound particles and deposition stripes on the plasma vessel hidden behind the graphite tiles. In order to understand the possible causes, their implication and steps to avoid some of these problems for the next phase of machine operation, an assessment was made. The melting events should be avoided in the future, the others are due to usual plasma-wall interaction mechanisms and will be monitored after each campaign.

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Validating the ASCOT modelling of NBI fast ions in Wendelstein 7-X stellarator

Cited by 21 publications

References 11 publications

First neutral beam experiments on Wendelstein 7-X

First neutral beam experiments on Wendelstein 7-X

Operation of W7-X With an Inertially Cooled Divertor—On the Way to Steady State Operation

Inspection of W 7-X plasma-facing components after the operation phase OP1.2b: observations and first assessments

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