Wall conditioning at the Wendelstein 7-X stellarator operating with a graphite divertor

Wall conditioning plays an important role in achieving record plasma performance on the superconducting stellarator Wendelstein 7-X (W7-X) by controlling plasma density and maintaining low levels of impurities. The development of the optimal wall conditioning strategy is of high importance for succe...

Full description

Saved in:
Bibliographic Details
Published in:Physica scripta 2020-01, Vol.T171 (1), p.14063
Main Authors: Goriaev, A, Wauters, T, Brakel, R, Brezinsek, S, Dinklage, A, Fellinger, J, Grote, H, Moseev, D, Sereda, S, Volzke, O
Format: Article
Language:English
Subjects:
Astrophysics
baking
boronisation
ECWC
GDC
He pulse train
Physics
W7-X
wall conditioning
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Wall conditioning plays an important role in achieving record plasma performance on the superconducting stellarator Wendelstein 7-X (W7-X) by controlling plasma density and maintaining low levels of impurities. The development of the optimal wall conditioning strategy is of high importance for successful operation of the W7-X with a graphite divertor. The current strategy consists of initial wall conditioning applied prior to a physics experimental program and wall conditioning techniques executed during the plasma operation phase. The combination of baking and glow discharge cleaning provides a fast start to reliable plasma operation. Regular boronisation opens a new operational window of high plasma densities above 1 * 1020 m−3. Strong wall fueling remains, however, one of the main issues preventing plasma density control. A reliable solution is provided by application of He electron cyclotron resonance heating pulse trains, which are optimised to maximise fuel removal.
ISSN:0031-8949
1402-4896
DOI:10.1088/1402-4896/ab60fa