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O: Fachverband Oberflächenphysik

O 78: Vacuum Science & Technology: Theory and Applications I

O 78.1: Hauptvortrag

Donnerstag, 12. März 2026, 10:30–11:00, HSZ/0401

The Wendelstein 7-X plasma vessel vacuum system from a scientific perspective — •Georg Schlisio¹, Torsten Bräuer¹, Stylianos Varoutis¹, Paul McNeely¹, Dirk Hartmann¹, Chandra Prakash Dhard¹, Dirk Naujoks¹, Victoria Hak¹, and the W7-X team² — ¹Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald — ²See author list of O. Grulke et al. Nuclear Fusion, 64(11), 112002 (2024)

Wendelstein 7-X (W7-X) is the world's most advanced stellarator, a long-overlooked concept for magnetic confinement fusion. Fusion devices require excellent vacuum conditions to minimize impurity influx and charge-exchange losses during high-temperature plasma operation. The W7-X plasma vessel vacuum system comprises the main vessel, 254 vacuum ports, and several auxiliary diagnostic vacuum systems, the largest of which is the Neutral Beam Injection (NBI) system.

We describe the W7-X plasma vessel vacuum system and its instrumentation for total and partial pressure measurements. A key parameter for valve and gauge calibration, as well as for exhaust quantifi- cation, is the effective plasma-vessel volume; we outline an approach for determining this volume with sufficient precision. We also report experimentally derived pumping speeds of the turbomolecular pumps (TMPs) and cryo vacuum pumps (CVPs), which are essential inputs for modelling and exhaust analysis.

As an application of these capabilities, a recent study of gas-species transport in the sub-divertor region is shown, comparing experimental measurements with modelling results.

Keywords: high temperature plasma physics; vacuum; magnetic confinement fusion; nuclear fusion; stellarator