Explanipedia

Study of ion-to-electron temperature ratio at the edge of Wendelstein 7-X using a fast swept ball-pen probe Open

D. Cipciar, Jiřı́ Adámek, C. Killer, D. M. Kriete, V. Winters , et al. · 2025

In the Wendelstein 7-X (W7-X) stellarator, a ball-pen probe (BPP) has been routinely employed to measure in the island scrape-off layer (SOL) across large parts of the recent 2024/2025 campaigns. The high temporal resolution of a…

Surface loss probabilities of boron-hydride radicals in W7-X and ASDEX Upgrade Open

M. Mayer, Sehoon An, T. Bräuer, D. Cipciar, C. P. Dhard , et al. · 2025

Gas puff imaging of plasma turbulence in the magnetic island scrape-off layer of W7-X Open

S. G. Baek, S. Ballinger, O. Grulke, C. Killer, A. von Stechow , et al. · 2025

Electric fields and stationary drift flows in the island divertor SOL of Wendelstein 7-X Open

C. Killer, D. Cipciar, S. G. Baek, S. Ballinger, A. von Stechow , et al. · 2025

In the island divertor scrape-off layer (SOL) of the Wendelstein 7-X stellarator, 2D-resolved Langmuir probe measurements uncover a complex spatial structure of electron temperature, density, and floating potential. Depending on details of…

Low frequency <i>m</i> = 1 modes during standard and improved confinement scenarios in W7-X Open

D. Cipciar, C. Killer, C. Brandt, A. Könies, K. Rahbarnia , et al. · 2025

In the Wendelstein 7-X stellarator (W7-X), two related global low-frequency electromagnetic oscillations are observed on many diagnostic systems (e.g. plasma stored energy, Mirnov coils, Langmuir probes, etc). The activity is related to th…

Numerical modeling of impurity powder injection in W7-X Open

F. Nespoli, Y. Feng, G. Kawamura, M. Shoji, R. Lunsford , et al. · 2024

In this work, we present numerical simulation results of powder injection in W7-X using the EMC3-EIRENE and DIS codes. First, we model powder injection experiments performed in W7-X with the Probe Mounted Powder Injector. The simulation re…

Estimation of turbulent transport coefficients by the conditional variance method Open

T. Tork, P. Mänz, N. H. Bian, F. Reimold, G. Grenfell , et al. · 2024

A novel approach for estimating turbulent transport coefficients in fusion devices is presented. The diagnostic method is established on the analysis of the conditional variance of one-point time series of density or temperature fluctuatio…

Gas puff imaging of plasma turbulence in the magnetic island scrape-off layer of W7-X Open

S. G. Baek, S. Ballinger, O. Grulke, C. Killer, A. von Stechow , et al. · 2024

The turbulence characteristics of the scrape-off-layer (SOL) plasma in the W7-X stellarator are investigated using a gas-puff-imaging (GPI) diagnostic, newly installed and operated during the OP 2.1 campaign. The SOL plasma on W7-X feature…

Properties of boron layers deposited during boronisations in W7-X Open

M. Mayer, M. Balden, T. Bräuer, D. Cipciar, C. P. Dhard , et al. · 2024

Boronisation was first used for wall conditioning in W7-X during the OP 1.2b operational period, which was characterized by the use of the fine-grain graphite Test Divertor Unit (TDU) and inertial cooling only. After this period, deposited…

Impact of spatially varying transport coefficients in EMC3-Eirene simulations of W7-X and assessment of drifts Open

D. Schwörer, F. Reimold, H. Niemann, Yu Gao, M. Jakubowski , et al. · 2024

Modelling the scrape-off layer of a stellarator is challenging due to the complex magnetic 3D geometry. The here presented study analyses simulations of the scrape-off layer (SOL) of the stellarator Wendelstein 7-X (W7-X) using spatially v…

Realization of a gas puff imaging system on the Wendelstein 7-X stellarator Open

J. L. Terry, A. von Stechow, S. G. Baek, S. Ballinger, O. Grulke , et al. · 2024

A system for studying the spatiotemporal dynamics of fluctuations in the boundary of the W7-X plasma using the “Gas-Puff Imaging” (GPI) technique has been designed, constructed, installed, and operated. This GPI system addresses a number o…

Validation of a synthetic fast ion loss detector model for Wendelstein 7-X Open

Alexandra LeViness, S. Lazerson, A. Jansen van Vuuren, J. Rueda-Rueda, M. Beurskens , et al. · 2024

We present the first validated synthetic diagnostic for fast ion loss detectors (FILDs) in the Wendelstein 7-X (W7-X) stellarator. This model has been developed on, and validated against experimental data from, a FILD provided by the Natio…

Impact of spatially varying transport coefficients in EMC3-Eirene simulations of W7-X and assessment of drifts Open

D. Schwörer, F. Reimold, H. Niemann, Yu Gao, M. Jakubowski , et al. · 2024

Modelling the scrape-off layer of a stellarator is challenging due to the complex magnetic 3D geometry. The here presented study analyses simulations of the scrape-off layer (SOL) of the stellarator Wendelstein 7-X (W7-X) using spatially v…

Fast ion confinement in the presence of core magnetic islands in Wendelstein 7-X Open

S. Lazerson, J. Geiger, D. Kulla, Alexandra LeViness, S. Bozhenkov , et al. · 2024

The effect of magnetic islands in the core region of Wendelstein 7-X (W7-X) on fast ion confinement is explored through simulations with the BEAMS3D code. A magnetic configuration where the island chain is shifted to all…

The Realization of a Gas Puff Imaging System on the Wendelstein 7-X Stellarator Open

J. L. Terry, A. von Stechow, S. G. Baek, S. Ballinger, O. Grulke , et al. · 2024

A system for studying the spatio-temporal dynamics of fluctuations in the boundary of the W7-X plasma using the Gas-Puff Imaging (GPI) technique has been designed, constructed, installed, and operated. This GPI system addresses a number of…

Coherence of turbulent structures with varying drive in stellarator edge plasmas Open

Paul Huslage, G. Birkenmeier, B. Shanahan, C. Killer · 2023

This work investigates the parallel coherence of plasma filaments through numerical simulations using the hot-ion two-fluid hermes-2 model within the BOUT++ framework. Realistic field lines in the scrape-off layer (SOL) of magnetic fusion …

Statistical analysis of plasma filaments in the island divertor of Wendelstein 7-X Open

B. Csillag, S. Zoletnik, C. Killer, M. Vécsei, G. Anda , et al. · 2023

Plasma filaments have been measured with alkali beam emission spectroscopy in the plasma edge, divertor island, and scrape-off layer of Wendelstein 7-X. Due to the high intensity of a 1–2 kHz plasma mode, a new, correlation based condition…

Demonstration of Power Exhaust Control by Impurity Seeding in the Island Divertor at Wendelstein 7-X Open

F. Effenberg, S. Brezinsek, Y. Feng, M. Jakubowski, R. König , et al. · 2023

Effective power exhaust by impurity seeding and its dependence on the gas species used was demonstrated in island divertor configurations for the first time at Wendelstein 7-X (W7-X). A systematic set of experiments has been conducted duri…

Effects of drifts on scrape-off layer transport in W7-X Open

D. M. Kriete, A. Pandey, V. Perseo, J.C. Schmitt, D.A. Ennis , et al. · 2022

Drifts affect particle, momentum, and energy transport in the scrape-off layer (SOL) of tokamaks and stellarators, altering plasma flows and creating asymmetries between divertors. To understand how drifts affect SOL transport in the W7-X …

On the interaction between the island divertor heat fluxes, the scrape-off layer radial electric field and the edge turbulence in Wendelstein 7-X plasmas Open

E. Maragkoudakis, D. Carralero, T. Estrada, T. Windisch, Yu Gao , et al. · 2022

The formation of the radial electric field, in the scrape-off layer (SOL) has been experimentally studied for attached divertor conditions in stellarator W7-X. The main objective of this study is to test the v…

Observation of non-thermal electrons outside the SOL in the Wendelstein 7-X stellarator Open

C. Killer, P. Aleynikov, C. Biedermann, C. P. Dhard, P. Drews , et al. · 2022

Hot spots and bright patterns on plasma-facing components (PFC) in visible light are observed in electron cyclotron resonance heated (ECRH) plasmas at low densities in the stellarator Wendelstein 7-X. The events are often located far outsi…

Radiation characteristics of detached divertor plasmas in W7-X Open

E. Wang, R. König, M. Krychowiak, S. Brezinsek, P. Drews , et al. · 2022

Detached divertor plasmas has been achieved by density ramp in W7-X. During the transition into detachment, the main divertor radiation region moves from the region close to the divertor targets to the region around LCFS. The typical spati…

Parametrisation of target heat flux distribution and study of transport parameters for boundary modelling in W7-X Open

David Bold, F. Reimold, H. Niemann, M. Jakubowski, C. Killer , et al. · 2022

Modelling the scrape-off layer (SOL) of a stellarator is challenging due to the complex magnetic 3D geometry. The here presented study analyses simulations of the SOL of the stellarator Wendelstein 7-X using the EMC3-EIRENE code for the ma…

Effect of magnetic geometry on the energy partition between ions and electrons in the scrape-off layer of magnetic fusion devices Open

Y. L. Li, Guosheng Xu, B. Dudson, X. Liu, Zhuo Huang , et al. · 2022

A universal energy partition mechanism between ions and electrons has been confirmed to exist in the scrape-off layer of both the WEST tokamak and the W7-X stellarator. A peaked plasma density structure induced by an infinite magnetic conn…

Nonlinear decay of high-power microwaves into trapped modes in inhomogeneous plasma Open

A. Tancetti, S. K. Nielsen, J. Rasmussen, E. Z. Gusakov, A. Yu. Popov , et al. · 2022

We present novel experimental evidence of parametric decay instability of microwave beams in the plasma edge of the Wendelstein 7-X stellarator. We propose that the instability is sustained by trapping of only one daughter wave in the non-…

Reciprocating probe measurements in the test divertor operation phase of Wendelstein 7-X Open

C. Killer, P. Drews, O. Grulke, A. Knieps, D. Nicolai , et al. · 2022

Reciprocating probes are a classic and widespread tool for the investigation of the edge and Scrape-Off Layer of magnetic fusion plasmas. In the Wendelstein 7-X (W7-X) stellarator, the Multi-Purpose Manipulator serves as a multi-user platf…

Parametrisation of target heat flux distribution and study of transport\n parameters for boundary modelling in W7-X Open

D. Schwörer, F. Reimold, H. Niemann, Yu Gao, M. Jakubowski , et al. · 2022

Modelling the scrape-off layer of a stellarator is challenging due to the\ncomplex magnetic 3D geometry. The here presented study analyses simulations of\nthe scrape-off layer (SOL) of the stellarator Wendelstein 7-X (W7-X) using the\nEMC3…

Analysis of hydrogen fueling, recycling, and confinement at Wendelstein 7-X via a single-reservoir particle balance Open

T. Kremeyer, R. König, S. Brezinsek, O. Schmitz, Y. Feng , et al. · 2022

A single-reservoir particle balance for the main plasma species hydrogen has been established for W7-X. This has enabled the quantitative characterization of the particle sources in the standard island divertor configuration for the first …

Reciprocating probe measurements in the test divertor operation phase of Wendelstein 7-X Open

C. Killer, P. Drews, O. Grulke, A. Knieps, D. Nicolai , et al. · 2022

Reciprocating probes are a classic and widespread tool for the investigation of the edge and Scrape-Off Layer of magnetic fusion plasmas. In the Wendelstein 7-X (W7-X) stellarator, the Multi-Purpose Manipulator serves as a multi-user platf…

Magnetic configuration scans during divertor operation of Wendelstein 7-X Open

T. Andreeva, J. Geiger, A. Dinklage, G. A. Wurden, H. Thomsen , et al. · 2021

Wendelstein 7-X (W7-X) (Greifswald, Germany) is an advanced stellarator, which uses the modular coil concept to realize a magnetic configuration optimized for fusion-relevant plasma properties. The magnet system of the machine allows a var…

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