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Title: Laser calibration of the DIII-D coherence imaging system

Abstract

Here, we describe an in situ calibration technique for Coherence Imaging Spectroscopy (CIS) that measures 2-D images of ion flows on DIII-D. A low power CW diode laser that is tuneable in the range 464-468 nm along with a precision wavemeter (10–5 nm resolution) is used to characterize the interferometer phase as a function of wavelength in the region of C iii (465 nm) and He ii (468 nm). The interferometer is stabilized both mechanically and thermally to minimize drift during the calibration. Optical stirring and an integration sphere are utilized to obtain spatially uniform calibration images. The quality of the calibration data enables a measurement of phase versus wavelength over approximately 10 fringes of the interferometer. These coefficients can also be related to the geometry of the optics and the birefringent crystal of the interferometer. On DIII-D, the integration sphere with the laser light is inserted into the CIS optical system between shots and the laser image and wavelength are automatically recorded, providing a zero velocity reference

Authors:
 [1];  [1];  [1]; ORCiD logo [2]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Australian National Univ., Canberra, ACT (Australia)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1545491
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 89; Journal Issue: 10; Conference: 22. Proceedings of the Topical Conference on High-Temperature Plasma Diagnostics, San Diego, CA (United States), Apr 2018; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY

Citation Formats

Allen, S. L., Samuell, C. M., Meyer, W. H., and Howard, J. Laser calibration of the DIII-D coherence imaging system. United States: N. p., 2018. Web. doi:10.1063/1.5038739.
Allen, S. L., Samuell, C. M., Meyer, W. H., & Howard, J. Laser calibration of the DIII-D coherence imaging system. United States. doi:10.1063/1.5038739.
Allen, S. L., Samuell, C. M., Meyer, W. H., and Howard, J. Wed . "Laser calibration of the DIII-D coherence imaging system". United States. doi:10.1063/1.5038739. https://www.osti.gov/servlets/purl/1545491.
@article{osti_1545491,
title = {Laser calibration of the DIII-D coherence imaging system},
author = {Allen, S. L. and Samuell, C. M. and Meyer, W. H. and Howard, J.},
abstractNote = {Here, we describe an in situ calibration technique for Coherence Imaging Spectroscopy (CIS) that measures 2-D images of ion flows on DIII-D. A low power CW diode laser that is tuneable in the range 464-468 nm along with a precision wavemeter (10–5 nm resolution) is used to characterize the interferometer phase as a function of wavelength in the region of C iii (465 nm) and He ii (468 nm). The interferometer is stabilized both mechanically and thermally to minimize drift during the calibration. Optical stirring and an integration sphere are utilized to obtain spatially uniform calibration images. The quality of the calibration data enables a measurement of phase versus wavelength over approximately 10 fringes of the interferometer. These coefficients can also be related to the geometry of the optics and the birefringent crystal of the interferometer. On DIII-D, the integration sphere with the laser light is inserted into the CIS optical system between shots and the laser image and wavelength are automatically recorded, providing a zero velocity reference},
doi = {10.1063/1.5038739},
journal = {Review of Scientific Instruments},
number = 10,
volume = 89,
place = {United States},
year = {2018},
month = {9}
}

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Works referenced in this record:

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    Coherence imaging spectroscopy at Wendelstein 7-X for impurity flow measurements
    journal, January 2020

    • Perseo, Valeria; Gradic, Dorothea; König, Ralf
    • Review of Scientific Instruments, Vol. 91, Issue 1
    • DOI: 10.1063/1.5126098

    Direct measurements of counter-streaming flows in a low-shear stellarator magnetic island topology
    journal, September 2019