skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Improved signal to noise ratio and sensitivity of an infrared imaging video bolometer on large helical device by using an infrared periscope

Abstract

An Infrared imaging Video Bolometer (IRVB) diagnostic is currently being used in the Large Helical Device (LHD) for studying the localization of radiation structures near the magnetic island and helical divertor X-points during plasma detachment and for 3D tomography. This research demands high signal to noise ratio (SNR) and sensitivity to improve the temporal resolution for studying the evolution of radiation structures during plasma detachment and a wide IRVB field of view (FoV) for tomography. Introduction of an infrared periscope allows achievement of a higher SNR and higher sensitivity, which in turn, permits a twofold improvement in the temporal resolution of the diagnostic. Higher SNR along with wide FoV is achieved simultaneously by reducing the separation of the IRVB detector (metal foil) from the bolometer's aperture and the LHD plasma. Altering the distances to meet the aforesaid requirements results in an increased separation between the foil and the IR camera. This leads to a degradation of the diagnostic performance in terms of its sensitivity by 1.5-fold. Using an infrared periscope to image the IRVB foil results in a 7.5-fold increase in the number of IR camera pixels imaging the foil. This improves the IRVB sensitivity which depends on the squaremore » root of the number of IR camera pixels being averaged per bolometer channel. Despite the slower f-number (f/# = 1.35) and reduced transmission (τ{sub 0} = 89%, due to an increased number of lens elements) for the periscope, the diagnostic with an infrared periscope operational on LHD has improved in terms of sensitivity and SNR by a factor of 1.4 and 4.5, respectively, as compared to the original diagnostic without a periscope (i.e., IRVB foil being directly imaged by the IR camera through conventional optics). The bolometer's field of view has also increased by two times. The paper discusses these improvements in apt details.« less

Authors:
;  [1]; ;  [2]; ;  [3]
  1. High Temperature Plasma Physics Research Division, The Graduate University of Advanced Studies, 322-6 Oroshi-cho, Toki 509-5292 (Japan)
  2. National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan)
  3. GENESIA Corporation, 3-38-4-601 Shimo-Renjaku, Mitaka, Tokyo 181-0013 (Japan)
Publication Date:
OSTI Identifier:
22308958
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BOLOMETERS; CAMERAS; COMPARATIVE EVALUATIONS; DIVERTORS; INFRARED SPECTRA; LENSES; LHD DEVICE; MAGNETIC ISLANDS; PERISCOPES; PLASMA; RESOLUTION; SENSITIVITY; SIGNAL-TO-NOISE RATIO; TOMOGRAPHY

Citation Formats

Pandya, Shwetang N., E-mail: pandya.shwetang@LHD.nifs.ac.jp, Sano, Ryuichi, Peterson, Byron J., Mukai, Kiyofumi, Enokuchi, Akito, and Takeyama, Norihide. Improved signal to noise ratio and sensitivity of an infrared imaging video bolometer on large helical device by using an infrared periscope. United States: N. p., 2014. Web. doi:10.1063/1.4891317.
Pandya, Shwetang N., E-mail: pandya.shwetang@LHD.nifs.ac.jp, Sano, Ryuichi, Peterson, Byron J., Mukai, Kiyofumi, Enokuchi, Akito, & Takeyama, Norihide. Improved signal to noise ratio and sensitivity of an infrared imaging video bolometer on large helical device by using an infrared periscope. United States. doi:10.1063/1.4891317.
Pandya, Shwetang N., E-mail: pandya.shwetang@LHD.nifs.ac.jp, Sano, Ryuichi, Peterson, Byron J., Mukai, Kiyofumi, Enokuchi, Akito, and Takeyama, Norihide. Tue . "Improved signal to noise ratio and sensitivity of an infrared imaging video bolometer on large helical device by using an infrared periscope". United States. doi:10.1063/1.4891317.
@article{osti_22308958,
title = {Improved signal to noise ratio and sensitivity of an infrared imaging video bolometer on large helical device by using an infrared periscope},
author = {Pandya, Shwetang N., E-mail: pandya.shwetang@LHD.nifs.ac.jp and Sano, Ryuichi and Peterson, Byron J. and Mukai, Kiyofumi and Enokuchi, Akito and Takeyama, Norihide},
abstractNote = {An Infrared imaging Video Bolometer (IRVB) diagnostic is currently being used in the Large Helical Device (LHD) for studying the localization of radiation structures near the magnetic island and helical divertor X-points during plasma detachment and for 3D tomography. This research demands high signal to noise ratio (SNR) and sensitivity to improve the temporal resolution for studying the evolution of radiation structures during plasma detachment and a wide IRVB field of view (FoV) for tomography. Introduction of an infrared periscope allows achievement of a higher SNR and higher sensitivity, which in turn, permits a twofold improvement in the temporal resolution of the diagnostic. Higher SNR along with wide FoV is achieved simultaneously by reducing the separation of the IRVB detector (metal foil) from the bolometer's aperture and the LHD plasma. Altering the distances to meet the aforesaid requirements results in an increased separation between the foil and the IR camera. This leads to a degradation of the diagnostic performance in terms of its sensitivity by 1.5-fold. Using an infrared periscope to image the IRVB foil results in a 7.5-fold increase in the number of IR camera pixels imaging the foil. This improves the IRVB sensitivity which depends on the square root of the number of IR camera pixels being averaged per bolometer channel. Despite the slower f-number (f/# = 1.35) and reduced transmission (τ{sub 0} = 89%, due to an increased number of lens elements) for the periscope, the diagnostic with an infrared periscope operational on LHD has improved in terms of sensitivity and SNR by a factor of 1.4 and 4.5, respectively, as compared to the original diagnostic without a periscope (i.e., IRVB foil being directly imaged by the IR camera through conventional optics). The bolometer's field of view has also increased by two times. The paper discusses these improvements in apt details.},
doi = {10.1063/1.4891317},
journal = {Review of Scientific Instruments},
number = 7,
volume = 85,
place = {United States},
year = {Tue Jul 15 00:00:00 EDT 2014},
month = {Tue Jul 15 00:00:00 EDT 2014}
}