Wendelstein 7-X Near Real-Time Image Diagnostic System for Plasma-Facing Components Protection

W7-X Team

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The Wendelstein 7-X (W7-X) fusion experiment is aimed at proving that the stellarator concept is suitable for a future fusion reactor. Therefore, it is designed for steady-state plasmas of up to 30 min, which means that the thermal control of the plasma-facing components (PFCs) is of vital importance to prevent damage to the device. In this paper an overview of the design of the Near Real-Time Image Diagnostic System (hereinafter called “the System”) for PFCs protection in W7-X is presented. The goal of the System is to monitor the PFCs with high risk of permanent damage due to local overheating during plasma operations and to send alarms to the interlock system. The monitoring of the PFCs is based on thermographic and video cameras, and their video streams are analyzed by means of graphics processing unit–based computer vision techniques to detect the strike line, hot spots, and other thermal events. The video streams and the detected thermal events are displayed online in the control room in the form of a thermal map and permanently stored in the database. In order to determine the emissivity and maximum temperature allowed, a pixel-based correspondence between the image and the observed device part is required. The three-dimensional geometry of W7-X makes the System particularly sensitive to the spatial calibration of the cameras since hot spots can be expected anywhere, and a full segmentation of the field of view is necessary, in contrast to other regions of interest–based systems. A precise registration of the field of view and a correction of the strong lens distortion caused by the wide-angle optical system are then required. During the next operation phase the uncooled graphite divertor units will allow the System to be tested without risk of damaging the divertors in preparation for when water-cooled high-heat-flux divertors will be used.

Original languageEnglish
Pages (from-to)1-9
Number of pages9
JournalFusion Science and Technology
DOIs
Publication statusAccepted/In press - Dec 28 2017

Fingerprint

Facings
Plasmas
field of view
cameras
damage
Graphite
stellarators
fusion reactors
warning systems
Fusion reactors
computer vision
Video cameras
emissivity
Optical systems
Computer vision
rooms
Heat flux
heat flux
Lenses
Fusion reactions

Keywords

  • imaging diagnostics
  • plasma-facing components
  • Wendelstein 7-X

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Materials Science(all)
  • Mechanical Engineering

Cite this

Wendelstein 7-X Near Real-Time Image Diagnostic System for Plasma-Facing Components Protection. / W7-X Team.

In: Fusion Science and Technology, 28.12.2017, p. 1-9.

Research output: Contribution to journalArticle

@article{d34e27321e3942b1a1b3a9614f367edf,
title = "Wendelstein 7-X Near Real-Time Image Diagnostic System for Plasma-Facing Components Protection",
abstract = "The Wendelstein 7-X (W7-X) fusion experiment is aimed at proving that the stellarator concept is suitable for a future fusion reactor. Therefore, it is designed for steady-state plasmas of up to 30 min, which means that the thermal control of the plasma-facing components (PFCs) is of vital importance to prevent damage to the device. In this paper an overview of the design of the Near Real-Time Image Diagnostic System (hereinafter called “the System”) for PFCs protection in W7-X is presented. The goal of the System is to monitor the PFCs with high risk of permanent damage due to local overheating during plasma operations and to send alarms to the interlock system. The monitoring of the PFCs is based on thermographic and video cameras, and their video streams are analyzed by means of graphics processing unit–based computer vision techniques to detect the strike line, hot spots, and other thermal events. The video streams and the detected thermal events are displayed online in the control room in the form of a thermal map and permanently stored in the database. In order to determine the emissivity and maximum temperature allowed, a pixel-based correspondence between the image and the observed device part is required. The three-dimensional geometry of W7-X makes the System particularly sensitive to the spatial calibration of the cameras since hot spots can be expected anywhere, and a full segmentation of the field of view is necessary, in contrast to other regions of interest–based systems. A precise registration of the field of view and a correction of the strong lens distortion caused by the wide-angle optical system are then required. During the next operation phase the uncooled graphite divertor units will allow the System to be tested without risk of damaging the divertors in preparation for when water-cooled high-heat-flux divertors will be used.",
keywords = "imaging diagnostics, plasma-facing components, Wendelstein 7-X",
author = "{W7-X Team} and {Puig Sitjes}, A. and M. Jakubowski and A. Ali and P. Drewelow and V. Moncada and F. Pisano and Ngo, {T. T.} and B. Cannas and Travere, {J. M.} and G. Kocsis and T. Szepesi and T. Szabolics",
year = "2017",
month = "12",
day = "28",
doi = "10.1080/15361055.2017.1396860",
language = "English",
pages = "1--9",
journal = "Fusion Science and Technology",
issn = "1536-1055",
publisher = "American Nuclear Society",

}

TY - JOUR

T1 - Wendelstein 7-X Near Real-Time Image Diagnostic System for Plasma-Facing Components Protection

AU - W7-X Team

AU - Puig Sitjes, A.

AU - Jakubowski, M.

AU - Ali, A.

AU - Drewelow, P.

AU - Moncada, V.

AU - Pisano, F.

AU - Ngo, T. T.

AU - Cannas, B.

AU - Travere, J. M.

AU - Kocsis, G.

AU - Szepesi, T.

AU - Szabolics, T.

PY - 2017/12/28

Y1 - 2017/12/28

N2 - The Wendelstein 7-X (W7-X) fusion experiment is aimed at proving that the stellarator concept is suitable for a future fusion reactor. Therefore, it is designed for steady-state plasmas of up to 30 min, which means that the thermal control of the plasma-facing components (PFCs) is of vital importance to prevent damage to the device. In this paper an overview of the design of the Near Real-Time Image Diagnostic System (hereinafter called “the System”) for PFCs protection in W7-X is presented. The goal of the System is to monitor the PFCs with high risk of permanent damage due to local overheating during plasma operations and to send alarms to the interlock system. The monitoring of the PFCs is based on thermographic and video cameras, and their video streams are analyzed by means of graphics processing unit–based computer vision techniques to detect the strike line, hot spots, and other thermal events. The video streams and the detected thermal events are displayed online in the control room in the form of a thermal map and permanently stored in the database. In order to determine the emissivity and maximum temperature allowed, a pixel-based correspondence between the image and the observed device part is required. The three-dimensional geometry of W7-X makes the System particularly sensitive to the spatial calibration of the cameras since hot spots can be expected anywhere, and a full segmentation of the field of view is necessary, in contrast to other regions of interest–based systems. A precise registration of the field of view and a correction of the strong lens distortion caused by the wide-angle optical system are then required. During the next operation phase the uncooled graphite divertor units will allow the System to be tested without risk of damaging the divertors in preparation for when water-cooled high-heat-flux divertors will be used.

AB - The Wendelstein 7-X (W7-X) fusion experiment is aimed at proving that the stellarator concept is suitable for a future fusion reactor. Therefore, it is designed for steady-state plasmas of up to 30 min, which means that the thermal control of the plasma-facing components (PFCs) is of vital importance to prevent damage to the device. In this paper an overview of the design of the Near Real-Time Image Diagnostic System (hereinafter called “the System”) for PFCs protection in W7-X is presented. The goal of the System is to monitor the PFCs with high risk of permanent damage due to local overheating during plasma operations and to send alarms to the interlock system. The monitoring of the PFCs is based on thermographic and video cameras, and their video streams are analyzed by means of graphics processing unit–based computer vision techniques to detect the strike line, hot spots, and other thermal events. The video streams and the detected thermal events are displayed online in the control room in the form of a thermal map and permanently stored in the database. In order to determine the emissivity and maximum temperature allowed, a pixel-based correspondence between the image and the observed device part is required. The three-dimensional geometry of W7-X makes the System particularly sensitive to the spatial calibration of the cameras since hot spots can be expected anywhere, and a full segmentation of the field of view is necessary, in contrast to other regions of interest–based systems. A precise registration of the field of view and a correction of the strong lens distortion caused by the wide-angle optical system are then required. During the next operation phase the uncooled graphite divertor units will allow the System to be tested without risk of damaging the divertors in preparation for when water-cooled high-heat-flux divertors will be used.

KW - imaging diagnostics

KW - plasma-facing components

KW - Wendelstein 7-X

UR - http://www.scopus.com/inward/record.url?scp=85048094600&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85048094600&partnerID=8YFLogxK

U2 - 10.1080/15361055.2017.1396860

DO - 10.1080/15361055.2017.1396860

M3 - Article

SP - 1

EP - 9

JO - Fusion Science and Technology

JF - Fusion Science and Technology

SN - 1536-1055

ER -