Ralf König

Multi-X-point radiation and its dynamics in up/down asymmetry in plasma detachment regimes in Wendelstein 7-X

Daihong Zhang, Gábor Cseh, Y. Feng, Yu Gao et autres

Abstract In Wendelstein 7-X (W7-X), stable plasma detachment in ECRH hydrogen plasmas is routinely achieved with the standard magnetic configuration, containing five magnetic islands in the scrape-off layer (SOL). Plasma detachment induced by intrinsic carbon impurities is characterized by a high radiation …

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First experimental confirmation of island SOL geometry effects in a high radiation regime on W7-X

Victoria R. Winters, F. Reimold, Y. Feng, Daihong Zhang et autres

Abstract This work characterizes the detachment behavior and radiation characteristics of the low iota configuration in the Wendelstein 7-X (W7-X) stellarator. The island scrape-off layer (SOL) of the low iota has a poloidal mode number of six islands surrounding the last closed …

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Multi-delay coherence imaging spectroscopy optimized for ion temperature measurements in the divertor plasma of the Wendelstein 7-X stellarator

David Matthew Kriete, V. Perseo, Dorothea Gradic, David A. Ennis et autres

A new coherence imaging spectroscopy (CIS) diagnostic optimized to measure the C2+ impurity ion temperature Ti spatial distribution in the divertor plasma of the W7-X stellarator is designed, tested, and validated. Using CIS to obtain Ti in the edge of magnetically confined …

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Conditions and benefits of X-point radiation for the island divertor

Y. Feng, Victoria R. Winters, Daihong Zhang, J. Geiger et autres

Abstract We present a method to geometrically quantify the three magnetic island chains with the poloidal mode numbers m = 4, 5, and 6 (referred to in this paper as high-iota, standard, and low-iota islands, respectively), on which the W7-X divertor relies. …

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Heat and particle exhaust in high-performance plasmas in Wendelstein 7-X

Yu Gao, J. Geiger, M. Jakubowski, Arun Pandey et autres

Abstract The paper reports for the first time the heat and particle exhaust at the plasma boundary through various edge diagnostics for the high-performance plasma obtained after pellet injection on Wendelstein 7-X. The plasma density at the edge is found to be …

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Observation of a drift-driven local transport regime in the island divertor of Wendelstein 7-X

E.R. Flom, David Matthew Kriete, M. Krychowiak, Nassim Maaziz et autres

Measurements of the poloidal electron density and temperature distribution in the W7-X island divertor reveal the existence of two distinct scrape-off layer transport regimes. At low and intermediate densities, $T_e$ profiles across the magnetic island are hollow, with a minimum at the …

Analysis of the neutral fluxes in the divertor region of Wendelstein 7-X under attached and detached conditions using EMC3-EIRENE

D. Boeyaert, Y. Feng, H. Frerichs, T. Kremeyer et autres

Abstract This paper analyzes the neutral fluxes in the divertor region of the W7-X standard configuration for different input powers, both under attached and detached conditions. The performed analysis is conducted through EMC3-EIRENE simulations. They show the importance of the horizontal divertor …

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Analysis of the neutral fluxes in the divertor region of Wendelstein 7-X under attached and detached conditions using EMC3-EIRENE

Dieter Boeyaerta, H. Frerichs, T. Kremeyer, D. Naujoks et autres

This paper analyzes the neutral fluxes in the divertor region of the W7-X standard configuration for different input powers, both under attached and detached conditions. The performed analysis is conducted through EMC3-EIRENE simulations. They show the importance of the horizontal divertor to …

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Corrigendum: Gas exhaust in the Wendelstein 7-X stellarator during the first divertor operation (2022 Nucl. Fusion 62 096016)

U. Wenzel, G. Schlisio, P. Drewelow, M. Krychowiak et autres

Abstract In the published paper titled ‘Gas exhaust in the Wendelstein 7-X stellarator during the first divertor operation’ (2022 Nucl. Fusion 62 096016 ), figure 8 was incorrect. This corrigendum provides the correct figure 8.

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

F. Effenberg, S. Brezinsek, M. Jakubowski, Ralf König et autres

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 during the first island divertor campaign, …

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Development of the W7-X Alkali Metal Beam Diagnostic Observation System for OP2

D. Nagy, S. Zoletnik, M. Otte, Miklós Vécsei et autres

On a Wendelstein 7-X (W7-X), an alkali metal beam (AMB) diagnostic system was installed in order to measure the plasma edge electron density profiles and turbulence transport. A sodium beam was injected in the plasma, and the light emission was observed by …

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First feedback-controlled divertor detachment in W7-X: Experience from TDU operation and prospects for operation with actively cooled divertor

M. Krychowiak, Ralf König, Tullio Barbui, S. Brezinsek et autres

In the last experimental campaign (OP1.2b) of the stellarator Wendelstein 7-X (W7-X), boronisation as a mean for first wall conditioning was applied for the first time which led to strongly reduced impurity fluxes from plasma-facing components. Thermal detachment at the uncooled target …

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