P. McNeely

NBI for W7-X: A Four-Operational Campaign Overview

P. McNeely, Da Hartmann, N. Rust, R. Schroeder et autres

Abstract The Stellarator Wendelstein 7-X (W7-X) used neutral beam injection (NBI) for plasma heating in the last four experimental campaigns (called OP1.2b, OP2.1, OP2.2, and OP2.3). The NBI system uses inductively coupled RF driven ion sources operating in Hydrogen. The sources operate …

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Overview of Wendelstein 7-X high-performance operation

O. Grulke, G. Acton, J. Adamek, D. Aggelis et autres

Abstract The Wendelstein 7-X (W7-X) stellarator has completed two consecutive experimental campaigns OP 2.2 (Sep.-Dec. 2024) and OP 2.3 (Feb.-May 2025) under a new operational strategy enabling more than one year of uninterrupted device availability. This approach, supported by exceptionally high subsystem …

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Tokamak level performance in the optimized stellarator Wendelstein 7-X with stable peaked density profiles

S. Bannmann, Oliver P. Ford, S. Bozhenkov, T. Stange et autres

Progress towards achieving net gain from nuclear fusion is typically characterized by the triple product nTτ. Although stellarators have several benefits for a reactor, such as the inherent steady-state capability and the lack of disruptions, the maximum achieved triple product has historically …

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Tokamak level performance in the optimized stellarator Wendelstein 7-X with stable peaked density profiles

S. ; https://orcid.org/0000-0003-0772-9278 Bannmann, O. ; https://orcid.org/0000-0002-5646-4758 Ford, S. ; https://orcid.org/0000-0003-4289-3532 Bozhenkov, T. ; https://orcid.org/0000-0003-4154-1455 Stange et autres

Overview of the first Wendelstein 7-X long pulse campaign with fully water-cooled plasma facing components

O. Grulke, Christopher G. Albert, P. Aleynikov, K. Aleynikova et autres

Abstract After a long device enhancement phase, scientific operation resumed in 2022. The main new device components are the water cooling of all plasma facing components and the new water-cooled high heat flux divertor units. Water cooling allowed for the first long-pulse …

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Particle transport in reduced turbulence neutral beam heated discharges at Wendelstein 7-X

S. Bannmann, Oliver P. Ford, Peter Zs. Poloskei, J. Svensson et autres

Abstract A spontaneous reduction in anomalous particle transport in the plasma core is seen experimentally in reproducible, purely neutral beam heated plasma phases at Wendelstein 7-X (W7-X). Heating and fueling the plasma exclusively with the neutral beam injection system for several seconds …

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Turbulence-reduced high-performance scenarios in Wendelstein 7-X

Oliver P. Ford, M. Beurskens, S. Bozhenkov, S. Lazerson et autres

Abstract In the Wendelstein 7-X (W7-X) stellarator, turbulence is the dominant transport mechanism in most discharges. This leads to a ‘clamping’ of ion temperature over a wide range of heating power, predominantly flat density profiles where hollow profiles driven by neoclassical thermo-diffusion …

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Bayesian inference of electron density and ion temperature profiles from neutral beam and halo Balmer-α emission at Wendelstein 7-X

S. Bannmann, Oliver P. Ford, U. Hoefel, Peter Zs. Poloskei et autres

Abstract By employing Bayesian inference techniques, the full electron density profile from the plasma core to the edge of Wendelstein 7-X (W7-X) is inferred solely from neutral hydrogen beam and halo Balmer-α (Hα) emission data. The halo is a cloud of neutrals …

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Experimental characterization of the active and passive fast-ion H-alpha emission in W7-X using FIDASIM

Peter Zs. Poloskei, Benedikt Geiger, A. Jansen van Vuuren, S. Äkäslompolo et autres

Abstract This paper presents the first results from the analysis of Balmer-alpha spectra at Wendelstein 7-X which contain the broad charge exchange emission from fast-ions. The measured spectra are compared to synthetic spectra predicted by the FIDASIM code, which has been supplied …

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Fast forward modeling of neutral beam injection and halo formation including full Balmer-α emission prediction at W7-X

S. Bannmann, Oliver P. Ford, U. Hoefel, Peter Zs. Poloskei et autres

Abstract A full collisional-radiative (CR) neutral beam injection model based on Gaussian pencil (Gausscil) beams and a diffusive CR neutral halo model are presented. The halo is a neutral cloud around the neutral beam forming due to multiple charge exchange (CX) reactions. …

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Predictive simulations of NBI ion power load to the ICRH antenna in Wendelstein 7-X

J. Kontula, S. Äkäslompolo, Atso Ikäheimo, S. Lazerson et autres

Abstract In Wendelstein 7-X (W7-X), a new ion cyclotron resonance heating (ICRH) antenna will be commissioned during the operational campaign OP2.1. The antenna will have to sustain power loads not only from thermal plasma and radiation but also fast ions. Predictive simulations …

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

Thomas Sunn Pedersen, I. Abramovič, N. Allen, T. Dittmar et autres