Development of glow discharge and electron cyclotron resonance heating conditioning on W7-X
For successful operation of Wendelstein 7-X (W7-X) control of plasma impurity content and fuel recycling is required. This can be achieved by using wall conditioning methods. During the first divertor operation campaign (OP1.2a) of W7-X glow discharge conditioning (GDC), weekly in hydrogen and daily...
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doaj-924cd984e68f4dc2b7a9358561b41d8a2020-11-25T00:44:24ZengElsevierNuclear Materials and Energy2352-17912019-01-0118227232Development of glow discharge and electron cyclotron resonance heating conditioning on W7-XA. Goriaev0T. Wauters1R. Brakel2H. Grote3M. Gruca4O. Volzke5S. Brezinsek6A. Dinklage7M. Kubkowska8U. Neuner9Laboratory for Plasma Physics, LPP-ERM/KMS, Brussels, Belgium; Department of Applied Physics, Ghent University, Belgium; Corresponding author at: Laboratory for Plasma Physics, LPP-ERM/KMS, Brussels, Belgium.Laboratory for Plasma Physics, LPP-ERM/KMS, Brussels, BelgiumMax-Planck-Institute for Plasma Physics, Greifswald, GermanyMax-Planck-Institute for Plasma Physics, Greifswald, GermanyInstitute of Plasma Physics and Laser Microfusion, Warsaw, PolandMax-Planck-Institute for Plasma Physics, Greifswald, GermanyInstitute of Energy and Climate Research – Plasma Physics, Forschungszentrum Jülich GmbH, Jülich, GermanyMax-Planck-Institute for Plasma Physics, Greifswald, GermanyInstitute of Plasma Physics and Laser Microfusion, Warsaw, PolandMax-Planck-Institute for Plasma Physics, Greifswald, GermanyFor successful operation of Wendelstein 7-X (W7-X) control of plasma impurity content and fuel recycling is required. This can be achieved by using wall conditioning methods. During the first divertor operation campaign (OP1.2a) of W7-X glow discharge conditioning (GDC), weekly in hydrogen and daily in helium for impurity and hydrogen removal respectively, was used in the absence of the magnetic field. He electron cyclotron resonance heating (ECRH) discharges were applied for density control in hydrogen plasmas during experimental days. The optimization of GDC and He ECRH wall conditioning on W7-X are presented. Solutions for glow discharge ignition problems are examined. The suitable He – GDC parameters, i.e. anode current and neutral gas pressure, are defined to keep the balance between maximum possible hydrogen removal rate and minimum plasma – facing component (PFC) erosion. Sequences of short He – ECRH pulses, so-called pulse trains, has been successfully implemented. The effect of pulse train main parameter variation such as gas prefill, input power, pulse length, duty cycle is described. The efficiency of single He recovery discharges and pulse trains are compared. The results of this work show significant improvement of wall cleaning efficiency. Keywords: W7-X, Wall conditioning, GDC, ECRH, Pulse train, Recovery dischargehttp://www.sciencedirect.com/science/article/pii/S2352179118302059 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
A. Goriaev T. Wauters R. Brakel H. Grote M. Gruca O. Volzke S. Brezinsek A. Dinklage M. Kubkowska U. Neuner |
spellingShingle |
A. Goriaev T. Wauters R. Brakel H. Grote M. Gruca O. Volzke S. Brezinsek A. Dinklage M. Kubkowska U. Neuner Development of glow discharge and electron cyclotron resonance heating conditioning on W7-X Nuclear Materials and Energy |
author_facet |
A. Goriaev T. Wauters R. Brakel H. Grote M. Gruca O. Volzke S. Brezinsek A. Dinklage M. Kubkowska U. Neuner |
author_sort |
A. Goriaev |
title |
Development of glow discharge and electron cyclotron resonance heating conditioning on W7-X |
title_short |
Development of glow discharge and electron cyclotron resonance heating conditioning on W7-X |
title_full |
Development of glow discharge and electron cyclotron resonance heating conditioning on W7-X |
title_fullStr |
Development of glow discharge and electron cyclotron resonance heating conditioning on W7-X |
title_full_unstemmed |
Development of glow discharge and electron cyclotron resonance heating conditioning on W7-X |
title_sort |
development of glow discharge and electron cyclotron resonance heating conditioning on w7-x |
publisher |
Elsevier |
series |
Nuclear Materials and Energy |
issn |
2352-1791 |
publishDate |
2019-01-01 |
description |
For successful operation of Wendelstein 7-X (W7-X) control of plasma impurity content and fuel recycling is required. This can be achieved by using wall conditioning methods. During the first divertor operation campaign (OP1.2a) of W7-X glow discharge conditioning (GDC), weekly in hydrogen and daily in helium for impurity and hydrogen removal respectively, was used in the absence of the magnetic field. He electron cyclotron resonance heating (ECRH) discharges were applied for density control in hydrogen plasmas during experimental days. The optimization of GDC and He ECRH wall conditioning on W7-X are presented. Solutions for glow discharge ignition problems are examined. The suitable He – GDC parameters, i.e. anode current and neutral gas pressure, are defined to keep the balance between maximum possible hydrogen removal rate and minimum plasma – facing component (PFC) erosion. Sequences of short He – ECRH pulses, so-called pulse trains, has been successfully implemented. The effect of pulse train main parameter variation such as gas prefill, input power, pulse length, duty cycle is described. The efficiency of single He recovery discharges and pulse trains are compared. The results of this work show significant improvement of wall cleaning efficiency. Keywords: W7-X, Wall conditioning, GDC, ECRH, Pulse train, Recovery discharge |
url |
http://www.sciencedirect.com/science/article/pii/S2352179118302059 |
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