Chandra Prakash Dhard

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

Matej Mayer, Sehoon An, Torsten Brauer, Dario Cipciar et autres

• The surface loss probabilities of boron hydride radicals created in boronisation plasmas in W7-X and ASDEX Upgrade were determined experimentally using the cavity technique. • The incident flux responsible for the growth of boron layers consists predominantly of radical ions, with …

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Numerical analysis of gas exhaust in Wendelstein 7-X using the direct simulation Monte Carlo method

S. Varoutis, Christos Tantos, Holger Strobel, D. Boeyaert et autres

Abstract The present work is focused on a 3D numerical assessment of the Wendelstein 7-X (W7-X) particle exhaust. For all the numerical simulations the direct simulation Monte Carlo solver of the DIVGAS workflow, has been employed. The complex 3D geometry of the …

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In-vessel colorimetry of Wendelstein 7-X first wall components after OP2.1

G. Motojima, S. Masuzaki, Chandra Prakash Dhard, D. Naujoks et autres

• The deposition layer distribution on the first wall panels has been estimated in W7-X by colorimetry. • No significant difference of net deposition layer thickness between OP1.2b and OP2.1 is evaluated. • A less deposition layer formation on the first wall …

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In-vessel inspection of arc traces on the W7-X plasma facing components after the operation phase OP2.1

Dogyun Hwangbo, Chandra Prakash Dhard, Shin Kajita, D. Naujoks et autres

Updated distribution of arc traces across the interior walls after the operation phase 2.1 of Wendelstein 7-X (W7-X) is reported. A total of 105 new arc places were found, with 95% of them located around the stainless steel panels, diagnostic ports, and …

Properties of boron layers deposited during boronisations in W7-X

Matej Mayer, Martin Balden, Torsten Brauer, Dario Cipciar et autres

• Properties of boronisation layers have been measured in W7-X after the operational period OP 1.2b. • Properties of boronisation layers have been measured during individual boronisations in OP 2.1. • Boronisation layers deposited during individual boronisations are relatively thin, with layer …

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First operation and validation of simulations for the divertor cryo-vacuum pump in Wendelstein 7-X

Victoria Haak, Chandra Prakash Dhard, D. Boeyaert, Torsten Brauer et autres

Ten cryo-vacuum pumps (CVPs) were installed in the subdivertor region of each island divertor in the stellarator Wendelstein 7-X (W7-X) and operated for the first time during the recently completed plasma campaign OP2.1. A pumping speed of 70 ± 1 m 3 …

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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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Migration and balance of 13C in the stellarator Wendelstein 7-X after 13CH 4 local injection into the island divertor

C. Kawan, S. Brezinsek, Timo Dittmar, Chandra Prakash Dhard et autres

A 13C tracer experiment was carried out to investigate impurity transport and migration in the stellarator Wendelstein 7-X (W7-X). About 4.0 × 1022 molecules of 13C marked methane were injected through the divertor gas injection system during plasma operation. After the experiment, …

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Numerical simulation of neutral gas dynamics in the W7-X sub-divertor

S. Varoutis, Christos Tantos, Holger Strobel, Christian Day et autres

Abstract The present work presents a 2D and 3D modeling of the neutral gas flow in the sub-divertor region of the W7-X. The investigations have been done using the DIVGAS code. The complex 2D and 3D geometries of the divertor components in …

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Exposure of tungsten heavy alloys at high thermal loads in LHD

Chandra Prakash Dhard, S. Masuzaki, D. Naujoks, R. Neu et autres

Tungsten has been considered a plasma-facing material in a future fusion reactor because of its low sputtering yield and low fuel retention. It has been examined in several tokamaks. In stellarators, it has recently been used for some plasma-facing components. However, in …

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Erosion and redeposition pattern on the W7-X graphite test divertor unit tile

Elzbieta Fortuna-Zalesna, Witold Zieliński, Lukasz Ciupinski, Maciej Spychalski et autres

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Improvement in the simulation tools for heat distribution predictions and control of baffle and middle divertor loads in Wendelstein 7-X

Yu Gao, Y. Feng, M. Endler, M. Jakubowski et autres

Abstract In the first divertor campaign in Wendelstein 7-X (W7-X), unexpected significant heat loads were observed at particular plasma-facing components (e.g. baffle tiles and middle divertor part) which were not designed to receive high heat flux. In a prior investigation, it was …

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