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Title: A high resolution IR/visible imaging system for the W7-X limiter

Abstract

A high-resolution imaging system, consisting of megapixel mid-IR and visible cameras along the same line of sight, has been prepared for the new W7-X stellarator and was operated during Operational Period 1.1 to view one of the five inboard graphite limiters. The radial line of sight, through a large diameter (184 mm clear aperture) uncoated sapphire window, couples a direct viewing 1344 × 784 pixel FLIR SC8303HD camera. A germanium beam-splitter sends visible light to a 1024 × 1024 pixel Allied Vision Technologies Prosilica GX1050 color camera. Both achieve sub-millimeter resolution on the 161 mm wide, inertially cooled, segmented graphite tiles. The IR and visible cameras are controlled via optical fibers over full Camera Link and dual GigE Ethernet (2 Gbit/s data rates) interfaces, respectively. While they are mounted outside the cryostat at a distance of 3.2 m from the limiter, they are close to a large magnetic trim coil and require soft iron shielding. We have taken IR data at 125 Hz to 1.25 kHz frame rates and seen that surface temperature increases in excess of 350 °C, especially on leading edges or defect hot spots. The IR camera sees heat-load stripe patterns on the limiter and has been usedmore » to infer limiter power fluxes (∼1–4.5 MW/m{sup 2}), during the ECRH heating phase. IR images have also been used calorimetrically between shots to measure equilibrated bulk tile temperature, and hence tile energy inputs (in the range of 30 kJ/tile with 0.6 MW, 6 s heating pulses). Small UFO’s can be seen and tracked by the FLIR camera in some discharges. The calibrated visible color camera (100 Hz frame rate) has also been equipped with narrow band C-III and H-alpha filters, to compare with other diagnostics, and is used for absolute particle flux determination from the limiter surface. Sometimes, but not always, hot-spots in the IR are also seen to be bright in C-III light.« less

Authors:
 [1];  [2]; ; ;  [3]
  1. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
  2. University of Wisconsin, Madison, Wisconsin 53706 (United States)
  3. Max Planck Institut für Plasma Physik, Wendelsteinstrasse 1, 17491 Greifswald (Germany)
Publication Date:
OSTI Identifier:
22596488
Resource Type:
Journal Article
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 87; Journal Issue: 11; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0034-6748
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; CAMERAS; COLOR; COMPARATIVE EVALUATIONS; CRYOSTATS; ECR HEATING; GERMANIUM; GRAPHITE; HEATING LOAD; HOT SPOTS; IMAGES; IRON; KHZ RANGE 01-100; LIMITERS; NEAR INFRARED RADIATION; OPTICAL FIBERS; PARTICLE TRACKS; RESOLUTION; SAPPHIRE; VISIBLE RADIATION

Citation Formats

Wurden, G. A., E-mail: wurden@lanl.gov, Dunn, J. P., Stephey, L. A., Biedermann, C., Jakubowski, M. W., and Gamradt, M. A high resolution IR/visible imaging system for the W7-X limiter. United States: N. p., 2016. Web. doi:10.1063/1.4960596.
Wurden, G. A., E-mail: wurden@lanl.gov, Dunn, J. P., Stephey, L. A., Biedermann, C., Jakubowski, M. W., & Gamradt, M. A high resolution IR/visible imaging system for the W7-X limiter. United States. https://doi.org/10.1063/1.4960596
Wurden, G. A., E-mail: wurden@lanl.gov, Dunn, J. P., Stephey, L. A., Biedermann, C., Jakubowski, M. W., and Gamradt, M. 2016. "A high resolution IR/visible imaging system for the W7-X limiter". United States. https://doi.org/10.1063/1.4960596.
@article{osti_22596488,
title = {A high resolution IR/visible imaging system for the W7-X limiter},
author = {Wurden, G. A., E-mail: wurden@lanl.gov and Dunn, J. P. and Stephey, L. A. and Biedermann, C. and Jakubowski, M. W. and Gamradt, M.},
abstractNote = {A high-resolution imaging system, consisting of megapixel mid-IR and visible cameras along the same line of sight, has been prepared for the new W7-X stellarator and was operated during Operational Period 1.1 to view one of the five inboard graphite limiters. The radial line of sight, through a large diameter (184 mm clear aperture) uncoated sapphire window, couples a direct viewing 1344 × 784 pixel FLIR SC8303HD camera. A germanium beam-splitter sends visible light to a 1024 × 1024 pixel Allied Vision Technologies Prosilica GX1050 color camera. Both achieve sub-millimeter resolution on the 161 mm wide, inertially cooled, segmented graphite tiles. The IR and visible cameras are controlled via optical fibers over full Camera Link and dual GigE Ethernet (2 Gbit/s data rates) interfaces, respectively. While they are mounted outside the cryostat at a distance of 3.2 m from the limiter, they are close to a large magnetic trim coil and require soft iron shielding. We have taken IR data at 125 Hz to 1.25 kHz frame rates and seen that surface temperature increases in excess of 350 °C, especially on leading edges or defect hot spots. The IR camera sees heat-load stripe patterns on the limiter and has been used to infer limiter power fluxes (∼1–4.5 MW/m{sup 2}), during the ECRH heating phase. IR images have also been used calorimetrically between shots to measure equilibrated bulk tile temperature, and hence tile energy inputs (in the range of 30 kJ/tile with 0.6 MW, 6 s heating pulses). Small UFO’s can be seen and tracked by the FLIR camera in some discharges. The calibrated visible color camera (100 Hz frame rate) has also been equipped with narrow band C-III and H-alpha filters, to compare with other diagnostics, and is used for absolute particle flux determination from the limiter surface. Sometimes, but not always, hot-spots in the IR are also seen to be bright in C-III light.},
doi = {10.1063/1.4960596},
url = {https://www.osti.gov/biblio/22596488}, journal = {Review of Scientific Instruments},
issn = {0034-6748},
number = 11,
volume = 87,
place = {United States},
year = {Tue Nov 15 00:00:00 EST 2016},
month = {Tue Nov 15 00:00:00 EST 2016}
}