A divertor scraper observation system for the Wendelstein 7-X stellarator

Wurden, G. A.; Fellinger, J.; Biedermann, C.; Drewelow, P.; Ford, O.; Gamradt, M.; Greve, H.; Herold, F.; Jakubowski, M.; Jenzsch, H.; Niemann, H.; Puig Sitjes, A.

doi:10.1063/1.5035078

Title: A divertor scraper observation system for the Wendelstein 7-X stellarator

Journal Article · Mon Aug 06 00:00:00 EDT 2018 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.5035078· OSTI ID:1467276

^[1]; Fellinger, J. ^[2]; Biedermann, C. ^[2];

^[2];

^[2]; Gamradt, M. ^[2]; Greve, H. ^[2]; Herold, F. ^[2];

^[2]; Jenzsch, H. ^[2]; Niemann, H. ^[2]; Puig Sitjes, A. ^[2]

Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, USA
Max-Planck-Institute für Plasma Physik, Wendelsteinstrasse 1, 17491 Greifswald, Germany

Two graphite divertor elements called scrapers have been installed on the Wendelstein 7-X stellarator in the throat of the magnetic island divertor. To diagnose one, we have designed, built, calibrated, and installed a new infrared/visible imaging endoscope system to enable detailed observations of the plasma interactions and heat loads at one of the scrapers and the nearby divertor surfaces. The new system uses a shuttered pinhole-protected pair of 90° off-axis 228 mm focal length aluminum parabolic mirrors, and two flat turning metal mirrors, to send light to a sapphire vacuum window 1.6 meters away, beyond which we have co-located telephoto lens-based infrared and visible cameras. The back-to-back off-axis parabolas serve to cancel out most aberrations, enabling the use of off-the-shelf commercial optics outside of the vessel. For the infrared, we use a 3-5 μm 1-megapixel FLIR SC8303HD camera and for the visible, a 5-megapixel CMOS PCO 5.5 edge camera. A short 1-m quartz pickoff fiber is used to send 200-1100 nm light to a compact spectrometer, also located in the same iron shield box as the cameras. The camera field of view covers the 700 mm length of the scraper, and includes locations monitored by thermocouples and Langmuir probes embedded in some of the scraper tiles. Predicted and actual optical test performances of the overall system are then compared.

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Research Organization:: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Fusion Energy Sciences (FES); European Commission (EC)

Contributing Organization:: W7-X Team

Grant/Contract Number:: AC52-06NA25396; 633053

OSTI ID:: 1467276

Alternate ID(s):: OSTI ID: 1463041

Report Number(s):: LA-UR-17-31225

Journal Information:: Review of Scientific Instruments, Vol. 89, Issue 10; Conference: High Temperature Plasma Diagnostics ; 2018-04-16 - 2018-04-16 ; San Diego, California, United States; ISSN 0034-6748

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 4 works

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References (7)

IR spectrometer using 90-degree off-axis parabolic mirrors Malone, Robert M.; Dolan, Daniel H.; Hacking, Richard G. Optical Engineering + Applications, SPIE Proceedings https://doi.org/10.1117/12.793790	conference	August 2008
Progress in the design and development of a test divertor (TDU) for the start of W7-X operation Peacock, A.; Greuner, H.; Hurd, F. Fusion Engineering and Design, Vol. 84, Issue 7-11 https://doi.org/10.1016/j.fusengdes.2009.01.053	journal	June 2009
Access to edge scenarios for testing a scraper element in early operation phases of Wendelstein 7-X Hölbe, H.; Sunn Pedersen, T.; Geiger, J. Nuclear Fusion, Vol. 56, Issue 2 https://doi.org/10.1088/0029-5515/56/2/026015	journal	January 2016
The new infrared imaging system on Alcator C-Mod Maqueda, R. J.; Wurden, G. A.; Terry, J. L. Review of Scientific Instruments, Vol. 70, Issue 1 https://doi.org/10.1063/1.1149496	journal	January 1999
A high resolution IR/visible imaging system for the W7-X limiter Wurden, G. A.; Stephey, L. A.; Biedermann, C. Review of Scientific Instruments, Vol. 87, Issue 11 https://doi.org/10.1063/1.4960596	journal	August 2016
Wendelstein 7-X Near Real-Time Image Diagnostic System for Plasma-Facing Components Protection Puig Sitjes, A.; Jakubowski, M.; Ali, A. Fusion Science and Technology, Vol. 74, Issue 1-2 https://doi.org/10.1080/15361055.2017.1396860	journal	December 2017
Overview of Design and Analysis Activities for the W7-X Scraper Element Lumsdaine, A.; Bjorholm, T.; Harris, J. IEEE Transactions on Plasma Science, Vol. 44, Issue 9 https://doi.org/10.1109/TPS.2016.2598486	journal	September 2016

Cited By (2)

Measurement and modeling of magnetic configurations to mimic overload scenarios in the W7-X stellarator Lore, J. D.; Gao, Y.; Geiger, J. Nuclear Fusion, Vol. 59, Issue 6 https://doi.org/10.1088/1741-4326/ab18d1	journal	May 2019
Infrared imaging systems for wall protection in the W7-X stellarator (invited) Jakubowski, Marcin; Drewelow, Peter; Fellinger, Joris Review of Scientific Instruments, Vol. 89, Issue 10 https://doi.org/10.1063/1.5038634	journal	October 2018

Figures / Tables (9)

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Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
47 OTHER INSTRUMENTATION
Magnetic Fusion Energy
Imaging diagnostic
Infrared
Visible
Divertor
wall protection
plasma