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

Journal Article · Mon Aug 08 00:00:00 EDT 2016 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.4959916· OSTI ID:1371879

Brookman, M. W.  ^[1]; Austin, M. E. ^[2]; McLean, A. G. ^[2]; Carlstrom, T. N. ^[3]; Hyatt, A. W. ^[3]; Lohr, J. ^[3]

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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)

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.

• Research Organization: General Atomics, San Diego, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Fusion Energy Sciences (FES)
• Grant/Contract Number: FC02-04ER54698; FG03-97ER54415
• OSTI ID: 1371879
• Journal Information: Review of Scientific Instruments, Vol. 87, 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); ISSN 0034-6748
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY