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Title: Evaluation of thermal helium beam and line-ratio fast diagnostic on the National Spherical Torus Experiment-Upgrade

A 1-D kinetic collisional radiative model (CRM) with state-of-the-art atomic data is developed and employed to simulate line emission to evaluate the Thermal Helium Beam (THB) diagnostic on NSTX-U. This diagnostic is currently in operation on RFX-mod, and it is proposed to be installed on NSTX-U. The THB system uses the intensity ratios of neutral helium lines 667.8, 706.5, and 728.1 nm to derive electron temperature (eV ) and density (cm–3) profiles. The purpose of the present analysis is to evaluate the applications of this diagnostic for determining fast (~4 μs) electron temperature and density radial profiles on the scrape-off layer (SOL) and edge regions of NSTX-U that are needed in turbulence studies. The diagnostic is limited by the level of detection of the 728.1 nm line, which is the weakest of the three. In conclusion, this study will also aid in future design of a similar 2-D diagnostic systems on the divertor.
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [1] ;  [1]
  1. Johns Hopkins Univ., Baltimore, MD (United States)
  2. INFN, Univ. di Padova, Padova (Italy)
  3. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Auburn Univ., Auburn, AL (United States)
  6. Univ. of Wisconsin-Madison, Madison, WI (United States)
Publication Date:
OSTI Identifier:
1248475
Grant/Contract Number:
AC02-09CH11466
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 23; Journal Issue: 5; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
Johns Hopkins Univ., Baltimore, MD (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
97 MATHEMATICS AND COMPUTING charge exchange reactions; computer modeling; tokamaks; plasma diagnostics; collision theories