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Title: Time-dependent analysis of visible helium line-ratios for electron temperature and density diagnostic using synthetic simulations on NSTX-U

Helium line-ratios for electron temperature (Te) and density (ne) plasma diagnostic in the Scrape-Off-Layer (SOL) and Edge regions of tokamaks are widely used. Due to their intensities and proximity of wavelengths, the singlet 667.8 and 728.1 nm, and triplet 706.5 nm visible lines have been typically preferred. Time-dependency of the triplet line (706.5 nm) has been previously analyzed in detail by including transient effects on line-ratios during gas-puff diagnostic applications. In this work, several line-ratio combinations within each of the two spin systems are analyzed with the purpose of eliminating transient effects to extend the application of this powerful diagnostic to high temporal resolution characterization of plasmas. The analysis is done using synthetic emission modeling and diagnostic for low electron density NSTX SOL plasma conditions by several visible lines. Quasi-static equilibrium, and time-dependent models are employed to evaluate transient effects of the atomic population levels that may affect the derived electron temperatures and densities as the helium gas-puff penetrates the plasma. Ultimately, the analysis of a wider range of spectral lines will help to extend this powerful diagnostic to experiments where the wavelength range of the measured spectra may be constrained either by limitations of the spectrometer, or by othermore » conflicting lines from different ions.« less
Authors:
 [1] ;  [2] ;  [2] ;  [1] ;  [1]
  1. Johns Hopkins Univ., Baltimore, MD (United States). Department of Physics and Astronomy
  2. Univ. of Wisconsin, Madison, WI (United States). Dept. of Engineering Physics
Publication Date:
OSTI Identifier:
1259296
Grant/Contract Number:
S0000787; AC02-09CH11466
Type:
Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 87; Journal Issue: 11; Conference: 21. Topical Conference on High-Temperature Plasma Diagnostics (HTPD 2016), Madison, WI (United States), 5-9 Jun 2016; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Research Org:
Johns Hopkins Univ., Baltimore, MD (United States); Univ. of Wisconsin, Madison, WI (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY Line-ratio diagnostics; plasma diagnostics