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Title: Improved cross-calibration of Thomson scattering and electron cyclotron emission with ECH on DIII-D

Thomson scattering (TS) produces n e profiles from measurement of scattered laser beam intensity. In the case of Rayleigh scattering, it provides a first calibration of the relation n e / ITS, which depends on many factors (e.g. laser alignment and power, optics, and measurement systems). On DIII-D, the n e calibration is adjusted for each laser and optic path against an absolute n e measurement from a density-driven cutoff on the 48 channel 2nd harmonic X-mode electron cyclotron emission (ECE) system. This method has been used to calibrate Thompson densities from the edge to near the core (r/a > 0.15). Application of core electron cyclotron heating improves the quality of cutoff and depth of its penetration into the core. ECH also changes underlying MHD activity. Furthermore, on the removal of ECH power, cutoff penetrates in from the edge to the core and channels fall successively and smoothly into cutoff. This improves the quality of the TS n e calibration while minimizing wall loading.
Authors:
ORCiD logo [1] ;  [2] ;  [2] ;  [3] ;  [3] ;  [3]
  1. Univ. of Texas, Austin, TX (United States). Inst. for Fusion Studies
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. General Atomics, San Diego, CA (United States)
Publication Date:
Grant/Contract Number:
FC02-04ER54698; FG03-97ER54415
Type:
Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 87; Journal Issue: 11; Related Information: M.W. Brookman, M.E. Austin, A.G. McLean, T.N. Carlstrom, A.W. Hyatt, and J. Lohr, "Improved cross-calibration of Thomson scattering and electron cyclotron emission with ECH on DIII-D", Rev. Sci. Instr. 87, 11E517 (2016); Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Research Org:
General Atomics, San Diego, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
OSTI Identifier:
1371879

Brookman, M. W., Austin, M. E., McLean, A. G., Carlstrom, T. N., Hyatt, A. W., and Lohr, J.. Improved cross-calibration of Thomson scattering and electron cyclotron emission with ECH on DIII-D. United States: N. p., Web. doi:10.1063/1.4959916.
Brookman, M. W., Austin, M. E., McLean, A. G., Carlstrom, T. N., Hyatt, A. W., & Lohr, J.. Improved cross-calibration of Thomson scattering and electron cyclotron emission with ECH on DIII-D. United States. doi:10.1063/1.4959916.
Brookman, M. W., Austin, M. E., McLean, A. G., Carlstrom, T. N., Hyatt, A. W., and Lohr, J.. 2016. "Improved cross-calibration of Thomson scattering and electron cyclotron emission with ECH on DIII-D". United States. doi:10.1063/1.4959916. https://www.osti.gov/servlets/purl/1371879.
@article{osti_1371879,
title = {Improved cross-calibration of Thomson scattering and electron cyclotron emission with ECH on DIII-D},
author = {Brookman, M. W. and Austin, M. E. and McLean, A. G. and Carlstrom, T. N. and Hyatt, A. W. and Lohr, J.},
abstractNote = {Thomson scattering (TS) produces ne profiles from measurement of scattered laser beam intensity. In the case of Rayleigh scattering, it provides a first calibration of the relation ne / ITS, which depends on many factors (e.g. laser alignment and power, optics, and measurement systems). On DIII-D, the ne calibration is adjusted for each laser and optic path against an absolute ne measurement from a density-driven cutoff on the 48 channel 2nd harmonic X-mode electron cyclotron emission (ECE) system. This method has been used to calibrate Thompson densities from the edge to near the core (r/a > 0.15). Application of core electron cyclotron heating improves the quality of cutoff and depth of its penetration into the core. ECH also changes underlying MHD activity. Furthermore, on the removal of ECH power, cutoff penetrates in from the edge to the core and channels fall successively and smoothly into cutoff. This improves the quality of the TS ne calibration while minimizing wall loading.},
doi = {10.1063/1.4959916},
journal = {Review of Scientific Instruments},
number = 11,
volume = 87,
place = {United States},
year = {2016},
month = {8}
}