S. Bannmann
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View article: Experimental power balance study on turbulent heat transport at Wendelstein 7-X
Experimental power balance study on turbulent heat transport at Wendelstein 7-X Open
Power balance analysis is used to compile an experimental database of turbulent heat transport in various plasma scenarios at the stellarator Wendelstein 7-X. As figures of merit for turbulence suppression, turbulent transport coefficients…
View article: The suppression of anomalous impurity transport above a critical normalized density gradient scale length in Wendelstein 7-X
The suppression of anomalous impurity transport above a critical normalized density gradient scale length in Wendelstein 7-X Open
In purely neutral-beam-heated scenarios in Wendelstein 7-X (W7-X), central peaking of impurity density profiles is observed. These are discharges typically considered as the main path towards high energy confinement in W7-X. Understanding …
View article: First motional stark effect measurements at Wendelstein 7-X
First motional stark effect measurements at Wendelstein 7-X Open
The rotational transform plays a crucial role in magnetic confinement devices and its profile is directly related to stability and confinement properties. A popular way to assess the rotational transform profile is using a Motional Stark E…
View article: Web apps for profile fitting and power balance analysis at Wendelstein 7-X
Web apps for profile fitting and power balance analysis at Wendelstein 7-X Open
Two novel web apps for W7-X are introduced: Profile Cooker and Power House. They are designed to streamline the workflow of profile fitting and power balance analysis while offering a graphical user interface that works in any common brows…
View article: Overview of the first Wendelstein 7-X long pulse campaign with fully water-cooled plasma facing components
Overview of the first Wendelstein 7-X long pulse campaign with fully water-cooled plasma facing components Open
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…
View article: Particle transport in reduced turbulence neutral beam heated discharges at Wendelstein 7-X
Particle transport in reduced turbulence neutral beam heated discharges at Wendelstein 7-X Open
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 neut…
View article: Visible core spectroscopy at <b>Wendelstein 7-X</b>
Visible core spectroscopy at <b>Wendelstein 7-X</b> Open
This paper presents an overview of recent hardware extensions and data analysis developments to the Wendelstein 7-X visible core spectroscopy systems. These include upgrades to prepare the in-vessel components for long-pulse operation, nin…
View article: Bayesian inference of electron density and ion temperature profiles from neutral beam and halo Balmer-α emission at Wendelstein 7-X
Bayesian inference of electron density and ion temperature profiles from neutral beam and halo Balmer-α emission at Wendelstein 7-X Open
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 (H α ) emission data. The halo is a c…
View article: Fast forward modeling of neutral beam injection and halo formation including full Balmer-α emission prediction at W7-X
Fast forward modeling of neutral beam injection and halo formation including full Balmer-α emission prediction at W7-X Open
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 charg…
View article: Core Diagnostics for WENDELSTEIN 7-X Steady-State Exploration Until 18 GJ
Core Diagnostics for WENDELSTEIN 7-X Steady-State Exploration Until 18 GJ Open
This contribution provides an overview of the core diagnostics as they are required for W7-X steady-state high-density operation with a divertor and profile control. The inferred profiles then address the stellarator optimization. A partic…
View article: Feasibility of neutral particle analysis for fast-ion measurements at W7-X
Feasibility of neutral particle analysis for fast-ion measurements at W7-X Open
A preliminary study investigating capabilities of a planned but not yet installed neutral particle analyzer (NPA) [1,2] system combined with a diagnostic neutral beam at Wendelstein 7-X (W7-X) [3] is presented. Additionally two NPAs viewin…
View article: 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 Open
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 1…