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Title: Midplane neutral density profiles in the National Spherical Torus Experiment

Abstract

Atomic and molecular density data in the outer midplane of NSTX [Ono et al., Nucl. Fusion 40, 557 (2000)] are inferred from tangential camera data via a forward modeling procedure using the DEGAS 2 Monte Carlo neutral transport code. The observed Balmer-b light emission data from 17 shots during the 2010 NSTX campaign display no obvious trends with discharge parameters such as the divertor Balmer-a emission level or edge deuterium ion density. Simulations of 12 time slices in 7 of these discharges produce molecular densities near the vacuum vessel wall of 2–8 x 1017 m-3 and atomic densities ranging from 1 to 7 x 1016 m-3; neither has a clear correlation with other parameters. Validation of the technique, begun in an earlier publication, is continued with an assessment of the sensitivity of the simulated camera image and neutral densities to uncertainties in the data input to the model. The simulated camera image is sensitive to the plasma profiles and virtually nothing else. The neutral densities at the vessel wall depend most strongly on the spatial distribution of the source; simulations with a localized neutral source yield densities within a factor of two of the baseline, uniform source, case. The uncertaintiesmore » in the neutral densities associated with other model inputs and assumptions are ≤ 50%.« less

Authors:
; ; ; ; ; ; ;
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
DOE Contract Number:  
AC02-09CH11466
Product Type:
Dataset
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Keywords:
NSTX; Neutrals; Monte-Carlo simulation; Edge plasma diagnostics
OSTI Identifier:
1366462
DOI:
10.11578/1366462

Citation Formats

Stotler, Daren, Scotti, F., Bell, R. E., Diallo, A., LeBlanc, B. P., Podesta, M., Roquemore, A. L., and Ross, P. W. Midplane neutral density profiles in the National Spherical Torus Experiment. United States: N. p., 2015. Web. doi:10.11578/1366462.
Stotler, Daren, Scotti, F., Bell, R. E., Diallo, A., LeBlanc, B. P., Podesta, M., Roquemore, A. L., & Ross, P. W. Midplane neutral density profiles in the National Spherical Torus Experiment. United States. doi:10.11578/1366462.
Stotler, Daren, Scotti, F., Bell, R. E., Diallo, A., LeBlanc, B. P., Podesta, M., Roquemore, A. L., and Ross, P. W. 2015. "Midplane neutral density profiles in the National Spherical Torus Experiment". United States. doi:10.11578/1366462. https://www.osti.gov/servlets/purl/1366462. Pub date:Sat Aug 01 00:00:00 EDT 2015
@article{osti_1366462,
title = {Midplane neutral density profiles in the National Spherical Torus Experiment},
author = {Stotler, Daren and Scotti, F. and Bell, R. E. and Diallo, A. and LeBlanc, B. P. and Podesta, M. and Roquemore, A. L. and Ross, P. W.},
abstractNote = {Atomic and molecular density data in the outer midplane of NSTX [Ono et al., Nucl. Fusion 40, 557 (2000)] are inferred from tangential camera data via a forward modeling procedure using the DEGAS 2 Monte Carlo neutral transport code. The observed Balmer-b light emission data from 17 shots during the 2010 NSTX campaign display no obvious trends with discharge parameters such as the divertor Balmer-a emission level or edge deuterium ion density. Simulations of 12 time slices in 7 of these discharges produce molecular densities near the vacuum vessel wall of 2–8 x 1017 m-3 and atomic densities ranging from 1 to 7 x 1016 m-3; neither has a clear correlation with other parameters. Validation of the technique, begun in an earlier publication, is continued with an assessment of the sensitivity of the simulated camera image and neutral densities to uncertainties in the data input to the model. The simulated camera image is sensitive to the plasma profiles and virtually nothing else. The neutral densities at the vessel wall depend most strongly on the spatial distribution of the source; simulations with a localized neutral source yield densities within a factor of two of the baseline, uniform source, case. The uncertainties in the neutral densities associated with other model inputs and assumptions are ≤ 50%.},
doi = {10.11578/1366462},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2015},
month = {8}
}

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Works referencing / citing this record:

Midplane neutral density profiles in the National Spherical Torus Experiment
journal, August 2015

  • Stotler, D. P.; Scotti, F.; Bell, R. E.
  • Physics of Plasmas, Vol. 22, Issue 8
  • DOI: 10.1063/1.4928372

Midplane neutral density profiles in the National Spherical Torus Experiment
journal, August 2015

  • Stotler, D. P.; Scotti, F.; Bell, R. E.
  • Physics of Plasmas, Vol. 22, Issue 8
  • DOI: 10.1063/1.4928372